< draft-ietf-anima-bootstrapping-keyinfra-07.txt   draft-ietf-anima-bootstrapping-keyinfra-08.txt >
ANIMA WG M. Pritikin ANIMA WG M. Pritikin
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Standards Track M. Richardson Intended status: Standards Track M. Richardson
Expires: January 4, 2018 SSW Expires: April 15, 2018 SSW
M. Behringer M. Behringer
S. Bjarnason
Cisco Cisco
S. Bjarnason
Arbor Networks
K. Watsen K. Watsen
Juniper Networks Juniper Networks
July 3, 2017 October 12, 2017
Bootstrapping Remote Secure Key Infrastructures (BRSKI) Bootstrapping Remote Secure Key Infrastructures (BRSKI)
draft-ietf-anima-bootstrapping-keyinfra-07 draft-ietf-anima-bootstrapping-keyinfra-08
Abstract Abstract
This document specifies automated bootstrapping of a remote secure This document specifies automated bootstrapping of a remote secure
key infrastructure (BRSKI) using vendor installed X.509 certificate, key infrastructure (BRSKI) using vendor installed X.509 certificate,
in combination with a vendor's authorizing service, both online and in combination with a vendor's authorizing service, both online and
offline. Bootstrapping a new device can occur using a routable offline. Bootstrapping a new device can occur using a routable
address and a cloud service, or using only link-local connectivity, address and a cloud service, or using only link-local connectivity,
or on limited/disconnected networks. Support for lower security or on limited/disconnected networks. Support for lower security
models, including devices with minimal identity, is described for models, including devices with minimal identity, is described for
skipping to change at page 1, line 40 skipping to change at page 1, line 41
device as well. device as well.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 4, 2018. This Internet-Draft will expire on April 15, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Other Bootstrapping Approaches . . . . . . . . . . . . . 4 1.1. Other Bootstrapping Approaches . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Scope of solution . . . . . . . . . . . . . . . . . . . . 7 1.3. Scope of solution . . . . . . . . . . . . . . . . . . . . 8
1.4. Leveraging the new key infrastructure / next steps . . . 9
2. Architectural Overview . . . . . . . . . . . . . . . . . . . 9 2. Architectural Overview . . . . . . . . . . . . . . . . . . . 9
2.1. Secure Imprinting using Vouchers . . . . . . . . . . . . 10 2.1. Behavior of a Pledge . . . . . . . . . . . . . . . . . . 11
2.2. Initial Device Identifier . . . . . . . . . . . . . . . . 10 2.2. Secure Imprinting using Vouchers . . . . . . . . . . . . 12
2.3. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 12 2.3. Initial Device Identifier . . . . . . . . . . . . . . . . 13
2.4. Lack of realtime clock . . . . . . . . . . . . . . . . . 14 2.4. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 14
2.5. Cloud Registrar . . . . . . . . . . . . . . . . . . . . . 15 2.4.1. Architectural component: Pledge . . . . . . . . . . . 16
3. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 15 2.4.2. Architectural component: Circuit Proxy . . . . . . . 16
3.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 17 2.4.3. Architectural component: Domain Registrar . . . . . . 16
3.1.1. Proxy Discovery Protocol Details . . . . . . . . . . 18 2.4.4. Architectural component: Vendor Service . . . . . . . 16
3.1.2. Registrar Discovery Protocol Details . . . . . . . . 18 2.5. Lack of realtime clock . . . . . . . . . . . . . . . . . 16
3.2. Request Voucher from the Registrar . . . . . . . . . . . 19 2.6. Cloud Registrar . . . . . . . . . . . . . . . . . . . . . 17
3.3. Request Voucher from MASA . . . . . . . . . . . . . . . . 20 2.7. Determining the MASA to contact . . . . . . . . . . . . . 17
3.4. Voucher Response . . . . . . . . . . . . . . . . . . . . 23 3. Voucher Request artifact . . . . . . . . . . . . . . . . . . 18
3.4.1. Completing authentication of Provisional TLS 3.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 18
connection . . . . . . . . . . . . . . . . . . . . . 24 3.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 19
3.5. Voucher Status Telemetry . . . . . . . . . . . . . . . . 25 3.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 21
3.6. MASA authorization log Request . . . . . . . . . . . . . 26 4. Proxy details . . . . . . . . . . . . . . . . . . . . . . . . 23
3.7. MASA authorization log Response . . . . . . . . . . . . . 26 4.1. Pledge discovery of Proxy . . . . . . . . . . . . . . . . 24
3.8. EST Integration for PKI bootstrapping . . . . . . . . . . 27 4.1.1. Proxy Grasp announcements . . . . . . . . . . . . . . 25
3.8.1. EST Distribution of CA Certificates . . . . . . . . . 28 4.2. CoAP connection to Registrar . . . . . . . . . . . . . . 26
3.8.2. EST CSR Attributes . . . . . . . . . . . . . . . . . 28 4.3. HTTPS proxy connection to Registrar . . . . . . . . . . . 26
3.8.3. EST Client Certificate Request . . . . . . . . . . . 29 4.4. Proxy discovery of Registrar . . . . . . . . . . . . . . 26
3.8.4. Enrollment Status Telemetry . . . . . . . . . . . . . 29 5. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 27
3.8.5. EST over CoAP . . . . . . . . . . . . . . . . . . . . 30 5.1. BRSKI-EST TLS establishment details . . . . . . . . . . . 29
4. Reduced security operational modes . . . . . . . . . . . . . 30 5.2. Pledge Requests Voucher from the Registrar . . . . . . . 30
4.1. Trust Model . . . . . . . . . . . . . . . . . . . . . . . 30 5.3. BRSKI-MASA TLS establishment details . . . . . . . . . . 31
4.2. Pledge security reductions . . . . . . . . . . . . . . . 31 5.4. Registrar Requests Voucher from MASA . . . . . . . . . . 31
4.3. Registrar security reductions . . . . . . . . . . . . . . 32 5.5. Voucher Response . . . . . . . . . . . . . . . . . . . . 34
4.4. MASA security reductions . . . . . . . . . . . . . . . . 33 5.5.1. Completing authentication of Provisional TLS
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 connection . . . . . . . . . . . . . . . . . . . . . 35
5.1. PKIX Registry . . . . . . . . . . . . . . . . . . . . . . 34 5.6. Voucher Status Telemetry . . . . . . . . . . . . . . . . 36
6. Security Considerations . . . . . . . . . . . . . . . . . . . 34 5.7. MASA authorization log Request . . . . . . . . . . . . . 37
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 35 5.7.1. MASA authorization log Response . . . . . . . . . . . 38
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 36 5.8. EST Integration for PKI bootstrapping . . . . . . . . . . 39
8.1. Normative References . . . . . . . . . . . . . . . . . . 36 5.8.1. EST Distribution of CA Certificates . . . . . . . . . 39
8.2. Informative References . . . . . . . . . . . . . . . . . 38 5.8.2. EST CSR Attributes . . . . . . . . . . . . . . . . . 40
Appendix A. IPv4 operations . . . . . . . . . . . . . . . . . . 39 5.8.3. EST Client Certificate Request . . . . . . . . . . . 41
A.1. IPv4 Link Local addresses . . . . . . . . . . . . . . . . 39 5.8.4. Enrollment Status Telemetry . . . . . . . . . . . . . 41
A.2. Use of DHCPv4 . . . . . . . . . . . . . . . . . . . . . . 39 5.8.5. EST over CoAP . . . . . . . . . . . . . . . . . . . . 42
Appendix B. mDNS / DNSSD proxy discovery options . . . . . . . . 39 6. Reduced security operational modes . . . . . . . . . . . . . 42
Appendix C. IPIP Join Proxy mechanism . . . . . . . . . . . . . 40 6.1. Trust Model . . . . . . . . . . . . . . . . . . . . . . . 42
C.1. Multiple Join networks on the Join Proxy side . . . . . . 41 6.2. Pledge security reductions . . . . . . . . . . . . . . . 43
C.2. Automatic configuration of tunnels on Registrar . . . . . 41 6.3. Registrar security reductions . . . . . . . . . . . . . . 44
C.3. Proxy Neighbor Discovery by Join Proxy . . . . . . . . . 42 6.4. MASA security reductions . . . . . . . . . . . . . . . . 44
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 45
7.1. PKIX Registry . . . . . . . . . . . . . . . . . . . . . . 45
7.2. MIME . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.3. Voucher Status Telemetry . . . . . . . . . . . . . . . . 47
8. Security Considerations . . . . . . . . . . . . . . . . . . . 47
8.1. Freshness in Voucher Requests . . . . . . . . . . . . . . 49
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 50
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 50
10.1. Normative References . . . . . . . . . . . . . . . . . . 50
10.2. Informative References . . . . . . . . . . . . . . . . . 52
Appendix A. IPv4 operations . . . . . . . . . . . . . . . . . . 53
A.1. IPv4 Link Local addresses . . . . . . . . . . . . . . . . 53
A.2. Use of DHCPv4 . . . . . . . . . . . . . . . . . . . . . . 54
Appendix B. mDNS / DNSSD proxy discovery options . . . . . . . . 54
Appendix C. IPIP Join Proxy mechanism . . . . . . . . . . . . . 55
C.1. Multiple Join networks on the Join Proxy side . . . . . . 55
C.2. Automatic configuration of tunnels on Registrar . . . . . 56
C.3. Proxy Neighbor Discovery by Join Proxy . . . . . . . . . 56
C.4. Use of connected sockets; or IP_PKTINFO for CoAP on C.4. Use of connected sockets; or IP_PKTINFO for CoAP on
Registrar . . . . . . . . . . . . . . . . . . . . . . . . 42 Registrar . . . . . . . . . . . . . . . . . . . . . . . . 56
C.5. Use of socket extension rather than virtual interface . . 42 C.5. Use of socket extension rather than virtual interface . . 57
Appendix D. To be deprecated: Consolidation remnants . . . . . . 43 Appendix D. MUD Extension . . . . . . . . . . . . . . . . . . . 57
D.1. Functional Overview . . . . . . . . . . . . . . . . . . . 43 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 59
D.1.1. Behavior of a Pledge . . . . . . . . . . . . . . . . 46
D.1.2. Behavior of a Join Proxy . . . . . . . . . . . . . . 52
D.1.3. Behavior of the Registrar . . . . . . . . . . . . . . 53
D.1.4. Behavior of the MASA Service . . . . . . . . . . . . 57
D.1.5. Leveraging the new key infrastructure / next steps . 58
D.1.6. Interactions with Network Access Control . . . . . . 58
D.2. Domain Operator Activities . . . . . . . . . . . . . . . 58
D.2.1. Instantiating the Domain Certification Authority . . 59
D.2.2. Instantiating the Registrar . . . . . . . . . . . . . 59
D.2.3. Accepting New Entities . . . . . . . . . . . . . . . 59
D.2.4. Automatic Enrollment of Devices . . . . . . . . . . . 60
D.2.5. Secure Network Operations . . . . . . . . . . . . . . 60
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 61
1. Introduction 1. Introduction
BRSKI provides a foundation to securely answer the following BRSKI provides a foundation to securely answer the following
questions between an element of the network domain called the questions between an element of the network domain called the
"Registrar" and an unconfigured and untouched device called a "Registrar" and an unconfigured and untouched device called a
"Pledge": "Pledge":
o Registrar authenticating the Pledge: "Who is this device? What is o Registrar authenticating the Pledge: "Who is this device? What is
its identity?" its identity?"
skipping to change at page 4, line 14 skipping to change at page 4, line 20
o Pledge authenticating the Registrar/Domain: "What is this domain's o Pledge authenticating the Registrar/Domain: "What is this domain's
identity?" identity?"
o Pledge authorization the Registrar: "Should I join it?" o Pledge authorization the Registrar: "Should I join it?"
This document details protocols and messages to the endpoints to This document details protocols and messages to the endpoints to
answer the above questions. The Registrar actions derive from Pledge answer the above questions. The Registrar actions derive from Pledge
identity, third party cloud service communications, and local access identity, third party cloud service communications, and local access
control lists. The Pledge actions derive from a cryptographically control lists. The Pledge actions derive from a cryptographically
protected "voucher" message delivered through the Registrar. protected "voucher" message delivered through the Registrar but
originating at a Manufacturer Authorized Signing Authority.
The syntactic details of vouchers are described in detail in The syntactic details of vouchers are described in detail in
[I-D.ietf-anima-voucher]. This document details automated protocol [I-D.ietf-anima-voucher]. This document details automated protocol
mechanisms to obtain vouchers. mechanisms to obtain vouchers, including the definition of a
necessary 'voucher request' message that is a minor extension to the
voucher format (see Section 3).
BRSKI results in the Pledge storing an X.509 root certificate BRSKI results in the Pledge storing an X.509 root certificate
sufficient for verifying the Registrar identity. In the process a sufficient for verifying the Registrar identity. In the process a
TLS connection is established which can be directly used for TLS connection is established which can be directly used for
Enrollment over Secure Transport (EST). The Pledge can use these Enrollment over Secure Transport (EST). In effect BRSKI provides an
credentials to secure additional protocol exchanges. automated mechanism for the "Bootstrap Distribution of CA
Certificates" described in [RFC7030] Section 4.1.1 wherein the Pledge
"MUST [...]. engage a human user to authorize the CA certificate
using out-of-band" information". With BRSKI the Pledge now can
automate this process using the voucher. Integration with a complete
EST enrollment is optional but trivial.
BRSKI is agile enough to support bootstrapping alternative key BRSKI is agile enough to support bootstrapping alternative key
infrastructures, such as a symmetric key solutions, but no such infrastructures, such as a symmetric key solutions, but no such
system is described in this document. system is described in this document.
1.1. Other Bootstrapping Approaches 1.1. Other Bootstrapping Approaches
To literally "pull yourself up by the bootstraps" is an impossible To literally "pull yourself up by the bootstraps" is an impossible
action. Similarly the secure establishment of a key infrastructure action. Similarly the secure establishment of a key infrastructure
without external help is also an impossibility. Today it is commonly without external help is also an impossibility. Today it is commonly
skipping to change at page 9, line 5 skipping to change at page 9, line 20
occurred, is not required, or is integrated by the proxy and occurred, is not required, or is integrated by the proxy and
registrar in such a way that the device itself does not need to be registrar in such a way that the device itself does not need to be
aware of the details. Although the use of an X.509 Initial Device aware of the details. Although the use of an X.509 Initial Device
Identity is consistant with IEEE 802.1AR [IDevID], and allows for Identity is consistant with IEEE 802.1AR [IDevID], and allows for
alignment with 802.1X network access control methods, its use here is alignment with 802.1X network access control methods, its use here is
for Pledge authentication rather than network access control. for Pledge authentication rather than network access control.
Integrating this protocol with network access control, perhaps as an Integrating this protocol with network access control, perhaps as an
Extensible Authentication Protocol (EAP) method (see [RFC3748]), is Extensible Authentication Protocol (EAP) method (see [RFC3748]), is
out-of-scope. out-of-scope.
1.4. Leveraging the new key infrastructure / next steps
As a result of the protocol described herein the bootstrapped devices
have a common trust anchor and a certificate has optionally been
issued from a local PKI. This makes it possible to automatically
deploy services across the domain in a secure manner.
Services which benefit from this:
o Device management.
o Routing authentication.
o Service discovery.
The major beneficiary is that it possible to use the credentials
deployed by this protocol to secure the Autonomic Control Plane (ACP)
([I-D.ietf-anima-autonomic-control-plane]).
2. Architectural Overview 2. Architectural Overview
The logical elements of the bootstrapping framework are described in The logical elements of the bootstrapping framework are described in
this section. Figure 1 provides a simplified overview of the this section. Figure 1 provides a simplified overview of the
components. Each component is logical and may be combined with other components. Each component is logical and may be combined with other
components as necessary. components as necessary.
. +------------------------+
.+------------------------+ +--------------Drop Ship--------------->| Vendor Service |
+--------------Drop Ship-------------->.| Vendor Service | | +------------------------+
| .+------------------------+ | | M anufacturer| |
| .| M anufacturer| | | | A uthorized |Ownership|
| .| A uthorized |Ownership| | | S igning |Tracker |
| .| S igning |Tracker | | | A uthority | |
| .| A uthority | | | +--------------+---------+
| .+--------------+---------+ | ^
| .............. ^ | | BRSKI-
V | V | MASA
+-------+ ............................................|... +-------+ ............................................|...
| | . | . | | . | .
| | . +------------+ +-----------+ | . | | . +------------+ +-----------+ | .
| | . | | | | | . | | . | | | | | .
|Pledge | . | Circuit | | Domain <-------+ . |Pledge | . | Circuit | | Domain <-------+ .
| | . | Proxy | | Registrar | . | | . | Proxy | | Registrar | .
| <--------> <-------> | . | <-------->............<-------> (PKI RA) | .
| | . | | | | . | | | BRSKI-EST | | .
|X.509 | . +------------+ +-----+-----+ . | | . | | +-----+-----+ .
|IDevID | . | . |IDevID | . +------------+ | EST RFC7030 .
| | . +-----------------+----------+ . | | . +-----------------+----------+ .
| | . | Key Infrastructure | . | | . | Key Infrastructure | .
| | . | (e.g. PKI Certificate | . | | . | (e.g. PKI Certificate | .
+-------+ . | Authority) | . +-------+ . | Authority) | .
. +----------------------------+ . . +----------------------------+ .
. . . .
................................................ ................................................
"Domain" components "Domain" components
Figure 1 Figure 1
skipping to change at page 10, line 8 skipping to change at page 10, line 48
be a Vendor Service for each vendor that supports devices following be a Vendor Service for each vendor that supports devices following
this document's specification, or an integrator could provide a this document's specification, or an integrator could provide a
generic service authorized by multiple vendors. It is unlikely that generic service authorized by multiple vendors. It is unlikely that
an integrator could provide Ownership Tracking services for multiple an integrator could provide Ownership Tracking services for multiple
vendors due to the required sales channel integrations necessary to vendors due to the required sales channel integrations necessary to
track ownership. track ownership.
The domain is the managed network infrastructure with a Key The domain is the managed network infrastructure with a Key
Infrastructure the Pledge is joining. The a domain provides initial Infrastructure the Pledge is joining. The a domain provides initial
device connectivity sufficient for bootstrapping with a Circuit device connectivity sufficient for bootstrapping with a Circuit
Proxy. The Domain registrar authenticates the Pledge, makes Proxy. The Domain Registrar authenticates the Pledge, makes
authorization decisions, and distributes vouchers obtained from the authorization decisions, and distributes vouchers obtained from the
Vendor Service. Optionally the Registrar also acts as a PKI Vendor Service. Optionally the Registrar also acts as a PKI
Registration Authority. Registration Authority.
2.1. Secure Imprinting using Vouchers 2.1. Behavior of a Pledge
The pledge goes through a series of steps which are outlined here at
a high level.
+--------------+
| Factory |
| default |
+------+-------+
|
+------v-------+
| Discover |
+------------> |
| +------+-------+
| |
| +------v-------+
| | Identity |
^------------+ |
| rejected +------+-------+
| |
| +------v-------+
| | Request |
| | Join |
| +------+-------+
| |
| +------v-------+
| | Imprint | Optional
^------------+ <--+Manual input (Appendix C)
| Bad Vendor +------+-------+
| response | send Voucher Status Telemetry
| +------v-------+
| | Enroll |
^------------+ |
| Enroll +------+-------+
| Failure |
| +------v-------+
| | Enrolled |
^------------+ |
Factory +--------------+
reset
Figure 2
State descriptions for the pledge are as follows:
1. Discover a communication channel to a Registrar.
2. Identify itself. This is done by presenting an X.509 IDevID
credential to the discovered Registrar (via the Proxy) in a TLS
handshake. (The Registrar credentials are only provisionally
accepted at this time).
3. Requests to Join the discovered Registrar. A unique nonce can be
included ensuring that any responses can be associated with this
particular bootstrapping attempt.
4. Imprint on the Registrar. This requires verification of the
vendor service provided voucher. A voucher contains sufficient
information for the Pledge to complete authentication of a
Registrar. (It enables the Pledge to finish authentication of
the Registrar TLS server certificate).
5. Enroll. By accepting the domain specific information from a
Registrar, and by obtaining a domain certificate from a Registrar
using a standard enrollment protocol, e.g. Enrollment over
Secure Transport (EST) [RFC7030].
6. The Pledge is now a member of, and can be managed by, the domain
and will only repeat the discovery aspects of bootstrapping if it
is returned to factory default settings.
2.2. Secure Imprinting using Vouchers
A voucher is a cryptographically protected statement to the Pledge A voucher is a cryptographically protected statement to the Pledge
device authorizing a zero-touch imprint on the Registrar domain. device authorizing a zero-touch imprint on the Registrar domain.
The format and cryptographic mechanism of vouchers is described in The format and cryptographic mechanism of vouchers is described in
detail in [I-D.ietf-anima-voucher]. detail in [I-D.ietf-anima-voucher].
Vouchers provide a flexible mechanism to secure imprinting: the Vouchers provide a flexible mechanism to secure imprinting: the
Pledge device only imprints when a voucher can be validated. At the Pledge device only imprints when a voucher can be validated. At the
lowest security levels the MASA server can indiscriminately issue lowest security levels the MASA server can indiscriminately issue
skipping to change at page 10, line 38 skipping to change at page 13, line 5
Pledge and Registrar devices that are to be widely deployed in the Pledge and Registrar devices that are to be widely deployed in the
field. The MASA vendor services have the flexibility to leverage field. The MASA vendor services have the flexibility to leverage
either the currently defined claim mechanisms or to experiment with either the currently defined claim mechanisms or to experiment with
higher or lower security levels. higher or lower security levels.
Vouchers provide a signed but non-encrypted communication channel Vouchers provide a signed but non-encrypted communication channel
between the Pledge, the MASA, and the Registrar. The Registrar between the Pledge, the MASA, and the Registrar. The Registrar
maintains control over the transport and policy decisions allowing maintains control over the transport and policy decisions allowing
the local security policy of the domain network to be enforced. the local security policy of the domain network to be enforced.
2.2. Initial Device Identifier 2.3. Initial Device Identifier
Pledge authentication is via an X.509 certificate installed during Pledge authentication and voucher request signing is via an X.509
the manufacturing process. This Initial Device Identifier provides a certificate installed during the manufacturing process. This Initial
basis for authenticating the Pledge during subsequent protocol Device Identifier provides a basis for authenticating the Pledge
exchanges and informing the Registrar of the MASA URI. There is no during subsequent protocol exchanges and informing the Registrar of
requirement for a common root PKI hierarchy. Each device vendor can the MASA URI. There is no requirement for a common root PKI
generate their own root certificate. hierarchy. Each device vendor can generate their own root
certificate.
The following previously defined fields are in the X.509 IDevID The following previously defined fields are in the X.509 IDevID
certificate: certificate:
o The subject field's DN encoding MUST include the "serialNumber" o The subject field's DN encoding MUST include the "serialNumber"
attribute with the device's unique serial number. attribute with the device's unique serial number.
o The subject-alt field's encoding SHOULD include a non-critical o The subject-alt field's encoding SHOULD include a non-critical
version of the RFC4108 defined HardwareModuleName. version of the RFC4108 defined HardwareModuleName.
skipping to change at page 11, line 30 skipping to change at page 13, line 46
The following newly defined field SHOULD be in the X.509 IDevID The following newly defined field SHOULD be in the X.509 IDevID
certificate: An X.509 non-critical certificate extension that certificate: An X.509 non-critical certificate extension that
contains a single Uniform Resource Identifier (URI) that points to an contains a single Uniform Resource Identifier (URI) that points to an
on-line Manufacturer Authorized Signing Authority. The URI is on-line Manufacturer Authorized Signing Authority. The URI is
represented as described in Section 7.4 of [RFC5280]. represented as described in Section 7.4 of [RFC5280].
Any Internationalized Resource Identifiers (IRIs) MUST be mapped to Any Internationalized Resource Identifiers (IRIs) MUST be mapped to
URIs as specified in Section 3.1 of [RFC3987] before they are placed URIs as specified in Section 3.1 of [RFC3987] before they are placed
in the certificate extension. The URI provides the authority in the certificate extension. The URI provides the authority
information. The BRSKI .well-known tree is described in Section 3 information. The BRSKI .well-known tree is described in Section 5
The new extension is identified as follows: The new extension is identified as follows:
<CODE BEGINS> <CODE BEGINS>
MASAURLExtnModule-2016 { iso(1) identified-organization(3) dod(6) MASAURLExtnModule-2016 { iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7) internet(1) security(5) mechanisms(5) pkix(7)
id-mod(0) id-mod-MASAURLExtn2016(TBD) } id-mod(0) id-mod-MASAURLExtn2016(TBD) }
DEFINITIONS IMPLICIT TAGS ::= BEGIN DEFINITIONS IMPLICIT TAGS ::= BEGIN
skipping to change at page 12, line 44 skipping to change at page 14, line 44
END END
<CODE ENDS> <CODE ENDS>
The choice of id-pe is based on guidance found in Section 4.2.2 of The choice of id-pe is based on guidance found in Section 4.2.2 of
[RFC5280], "These extensions may be used to direct applications to [RFC5280], "These extensions may be used to direct applications to
on-line information about the issuer or the subject". The MASA URL on-line information about the issuer or the subject". The MASA URL
is precisely that: online information about the particular subject. is precisely that: online information about the particular subject.
2.3. Protocol Flow 2.4. Protocol Flow
A representative flow is shown in Figure 2: A representative flow is shown in Figure 3:
+--------+ +---------+ +------------+ +------------+ +--------+ +---------+ +------------+ +------------+
| Pledge | | Circuit | | Domain | | Vendor | | Pledge | | Circuit | | Domain | | Vendor |
| | | Proxy | | Registrar | | Service | | | | Proxy | | Registrar | | Service |
| | | | | | | (Internet | | | | | | (JRC) | | (MASA) |
+--------+ +---------+ +------------+ +------------+ +--------+ +---------+ +------------+ +------------+
| | | | | | | Internet |
|<-RFC3927 IPv4 adr | Appendix A | | |<-RFC4862 IPv6 addr | | |
or|<-RFC4862 IPv6 adr | | | |<-RFC3927 IPv4 addr | Appendix A | |
| | | | | | | |
|-------------------->| | | |-------------------->| | |
| optional: mDNS query| Appendix B | | | optional: mDNS query| Appendix B | |
| RFC6763/RFC6762 | | | | RFC6763/RFC6762 | | |
| | | | | | | |
|<--------------------| | | |<--------------------| | |
| GRASP M_FLOOD | | | | GRASP M_FLOOD | | |
| periodic broadcast| | | | periodic broadcast| | |
| | | | | | | |
|<------------------->C<----------------->| | |<------------------->C<----------------->| |
| TLS via the Circuit Proxy | | | TLS via the Circuit Proxy | |
|<--Registrar TLS server authentication---| | |<--Registrar TLS server authentication---| |
[PROVISIONAL accept of server cert] | | [PROVISIONAL accept of server cert] | |
P---X.509 client authentication---------->| | P---X.509 client authentication---------->| |
P | | | P | | |
P---Request Voucher (include nonce)------>| | P---Voucher Request (include nonce)------>| |
P | | | P | | |
P | /---> | | P | /---> | |
P | | [accept device?] | P | | [accept device?] |
P | | [contact Vendor] | P | | [contact Vendor] |
P | | |--Pledge ID-------->| P | | |--Pledge ID-------->|
P | | |--Domain ID-------->| P | | |--Domain ID-------->|
P | | |--optional:nonce--->| P | | |--optional:nonce--->|
P | | | [extract DomainID] P | | | [extract DomainID]
P | | | | P | | | |
P | optional: | [update audit log] P | optional: | [update audit log]
P | |can | | P | |can | |
P | |occur | | P | |occur | |
P | |in | | P | |in | |
P | |advance | | P | |advance | |
P | | | | P | |if | |
P | | |<-device audit log--| P | |nonceless | |
P | | |<- voucher ---------| P | | |<- voucher ---------|
P | \----> | | P | \----> | |
P | | | P | | |
P | [verify audit log and voucher] |
P | | |
P<------voucher---------------------------| | P<------voucher---------------------------| |
[verify voucher ] | | | [verify voucher ] | | |
[verify provisional cert| | | [verify provisional cert| | |
| | | | | | | |
|---------------------------------------->| |
| [voucher status telemetry] |<-device audit log--|
| | [verify audit log and voucher] |
| | | |
|<--------------------------------------->| | |<--------------------------------------->| |
| Continue with RFC7030 enrollment | | | Continue with RFC7030 enrollment | |
| using now bidirectionally authenticated | | | using now bidirectionally authenticated | |
| TLS session. | | | | TLS session. | | |
| | | | | | | |
| | | |
| | | |
Figure 2 Figure 3
2.4. Lack of realtime clock 2.4.1. Architectural component: Pledge
The Pledge is the device which is attempting to join. Until the
pledge completes the enrollment process, it does has network
connectivity only to the Proxy.
2.4.2. Architectural component: Circuit Proxy
The (Circuit) Proxy provides HTTPS connectivity between the pledge
and the registrar. The proxy mechanism is described in Section 4,
with an optional stateless mechanism described in Appendix C.
2.4.3. Architectural component: Domain Registrar
The Domain Registrar (having the formal name Join Registrar/
Coordinator (JRC)), operates as a CMC Registrar, terminating the EST
and BRSKI connections. The Registrar is manually configured or
distributed with a list of trust anchors necessary to authenticate
any Pledge device expected on the network. The Registrar
communicates with the Vendor supplied MASA to establish ownership.
2.4.4. Architectural component: Vendor Service
The Vendor Service provides two logically seperate functions: the
Manufacturer Authorized Signing Authority (MASA), and an ownership
tracking/auditing function.
2.5. Lack of realtime clock
Many devices when bootstrapping do not have knowledge of the current Many devices when bootstrapping do not have knowledge of the current
time. Mechanisms like Network Time Protocols can not be secured time. Mechanisms like Network Time Protocols can not be secured
until bootstrapping is complete. Therefore bootstrapping is defined until bootstrapping is complete. Therefore bootstrapping is defined
in a method that does not require knowledge of the current time. in a method that does not require knowledge of the current time.
Unfortunately there are moments during bootstrapping when Unfortunately there are moments during bootstrapping when
certificates are verified, such as during the TLS handshake, where certificates are verified, such as during the TLS handshake, where
validity periods are confirmed. This paradoxical "catch-22" is validity periods are confirmed. This paradoxical "catch-22" is
resolved by the Pledge maintaining a concept of the current "window" resolved by the Pledge maintaining a concept of the current "window"
skipping to change at page 14, line 41 skipping to change at page 17, line 20
Registrar MUST support such lifetimes and SHOULD support ignoring Registrar MUST support such lifetimes and SHOULD support ignoring
Pledge lifetimes if they did not follow the RFC5280 Pledge lifetimes if they did not follow the RFC5280
recommendations. recommendations.
o The Pledge authenticates the voucher presented to it. During this o The Pledge authenticates the voucher presented to it. During this
authentication the Pledge ignores certificate lifetimes (by authentication the Pledge ignores certificate lifetimes (by
necessity because it does not have a realtime clock). necessity because it does not have a realtime clock).
o If the voucher contains a nonce then the Pledge MUST confirm the o If the voucher contains a nonce then the Pledge MUST confirm the
nonce matches the original voucher request. This ensures the nonce matches the original voucher request. This ensures the
voucher is fresh. See / (Section 3.2). voucher is fresh. See / (Section 5.2).
o Once the voucher is accepted the validity period of the o Once the voucher is accepted the validity period of the pinned-
domainCAcert in the voucher (see Section 3.4) now serves as a domain-cert in the voucher now serves as a valid time window. Any
valid time window. Any subsequent certificate validity periods subsequent certificate validity periods checked during RFC5280
checked during RFC5280 path validation MUST occur within this path validation MUST occur within this window.
window.
o When accepting an enrollment certificate the validity period o When accepting an enrollment certificate the validity period
within the new certificate is assumed to be valid by the Pledge. within the new certificate is assumed to be valid by the Pledge.
The Pledge is now willing to use this credential for client The Pledge is now willing to use this credential for client
authentication. authentication.
2.5. Cloud Registrar 2.6. Cloud Registrar
The Pledge MAY contact a well known URI of a cloud Registrar if a The Pledge MAY contact a well known URI of a cloud Registrar if a
local Registrar can not be discovered or if the Pledge's target use local Registrar can not be discovered or if the Pledge's target use
cases do not include a local Registrar. cases do not include a local Registrar.
If the Pledge uses a well known URI for contacting a cloud Registrar If the Pledge uses a well known URI for contacting a cloud Registrar
an Implicit Trust Anchor database (see [RFC7030]) MUST be used to an Implicit Trust Anchor database (see [RFC7030]) MUST be used to
authenticate service as described in RFC6125. This is consistent authenticate service as described in RFC6125. This is consistent
with the human user configuration of an EST server URI in [RFC7030] with the human user configuration of an EST server URI in [RFC7030]
which also depends on RFC6125. which also depends on RFC6125.
3. Protocol Details 2.7. Determining the MASA to contact
The Pledge MUST initiate BRSKI after boot if it is unconfigured. The The registrar needs to be able to contact a MASA that is trusted by
Pledge MUST NOT automatically initiate BRSKI if it has been the Pledge in order to obtain vouchers. There are three mechanisms
configured or is in the process of being configured. described:
BRSKI is described as extensions to EST [RFC7030] to reduce the The device's Initial Device Identifier will normally contain the MASA
number of TLS connections and crypto operations required on the URL as detailed in Section 2.3. This is the RECOMMENDED mechanism.
Pledge. The Registrar implements the BRSKI REST interface within the
same .well-known URI tree as the existing EST URIs as described in
EST [RFC7030] section 3.2.2. A MASA URI is therefore "https://
authority "./well-known/est".
Establishment of the TLS connection for bootstrapping is as specified If the Registrar is integrated with [I-D.ietf-opsawg-mud] and the
in EST [RFC7030] section 4.1.1 "Bootstrap Distribution of CA Pledge IDevID contains the id-pe-mud-url then the Registrar MAY
Certificates" [RFC7030] with the following extensions for automation: attempt to obtain the MASA URL from the MUD file. The MUD file
extension for the MASA URL is defined in Appendix D.
Automation extensions for the Pledge (equivalent to EST client) are: It can be operationally difficult to ensure the necessary X.509
extensions are in the Pledge's' IDevID due to the difficulty of
aligning current Pledge manufacturing with software releases and
development. As a final fallback the Registrar MAY be manually
configured or distributed with a MASA URL for each vendor. Note that
the Registrar can only select the configured MASA URL based on the
trust anchor -- so vendors can only leverage this approach if they
ensure a single MASA URL works for all Pledge's associated with each
trust anchor.
o The Pledge provisionally accepts the Registrar certificate during 3. Voucher Request artifact
the TLS handshake as detailed in EST.
o If the Registrar responds with a redirection to other web origins The voucher request is how an entity requests a voucher. The Pledge
the Pledge MUST follow only a single redirection. (EST supports forms a voucher request and submits it to the Registrar. The
redirection but does not allow redirections to other web origins Registrar in turn submits a voucher request to the MASA server. A
without user input). voucher request is a voucher structure with an additional "prior-
signed-voucher-request" "leaf to support forwarding the Pledge's
initial voucher request.
o The Registar MAY respond with an HTTP 202 ("the request has been Unless otherwise signaled (outside the voucher artifact), the signing
accepted for processing, but the processing has not been structure is as defined for vouchers, see [I-D.ietf-anima-voucher].
completed") as described in EST [RFC7030] section 4.2.3 wherein
the client "MUST wait at least the specified 'retry-after' time
before repeating the same request". The Pledge is RECOMMENDED to
provide local feed (blinked LED etc) during this wait cycle if
mechanisms for this are available. To prevent an attacker
Registrar from significantly delaying bootstrapping the Pledge
MUST limit the 'retry-after' time to 60 seconds. To avoid waiting
on a single erroneous Registrar the Pledge MUST drop the
connection after 5 seconds and proceed to other discovered
Registrars. Ideally the Pledge could keep track of the
appropriate retry-after value for any number of outstanding
Registrars but this would involve a large state table on the
Pledge. Instead the Pledge MAY ignore the exact retry-after value
in favor of a single hard coded value that takes effect between
discovery (Appendix D.1.1.1) attempts. A Registrar that is unable
to complete the transaction the first time due to timing reasons
will have future chances.
o The Pledge requests and validates a voucher using the new REST 3.1. Tree Diagram
calls described below.
o If necessary the Pledge calls the EST defined /cacerts method to The following tree diagram illustrates a high-level view of a voucher
obtain the current CA certificate. These are validated using the request document. The notation used in this diagram is described in
Voucher. [I-D.ietf-anima-voucher]. Each node in the diagram is fully
described by the YANG module in Section 3.3. Please review the YANG
module for a detailed description of the voucher request format.
o The Pledge completes authentication of the server certificate as module: ietf-voucher-request
detailed in Section 3.4.1. This moves the TLS connection out of groupings:
the provisional state. Optionally the TLS connection can now be voucher-request-grouping
used for EST enrollment. +---- voucher
+---- created-on? yang:date-and-time
+---- expires-on? yang:date-and-time
+---- assertion enumeration
+---- serial-number string
+---- idevid-issuer? binary
+---- pinned-domain-cert? binary
+---- domain-cert-revocation-checks? boolean
+---- nonce? binary
+---- last-renewal-date? yang:date-and-time
+---- prior-signed-voucher-request? binary
+---- proximity-registrar-cert? binary
The Pledge establishes the TLS connection with the Registrar through 3.2. Examples
the circuit proxy (see Appendix D.1.2) but the TLS connection is with
the Registar; so in the above section the "Pledge" is the TLS client
and the "Registrar" is the TLS server. All security associations
established are between the new device and the Registrar regardless
of proxy operations.
The extensions for a Registrar (equivalent to EST server) are: This section provides voucher examples for illustration purposes.
That these examples conform to the encoding rules defined in
[RFC7951].
o Client authentication is automated using Initial Device Identity. Example (1) The following example illustrates a Pledge generated
The subject field's DN encoding MUST include the "serialNumber" voucher-request. The assertion leaf is indicated as
attribute with the device's unique serial number. In the language 'proximity' and the Registrar's TLS server certificate
of RFC6125 this provides for a SERIALNUM-ID category of identifier is included in the 'pinned-domain-cert' leaf. See
that can be included in a certificate and therefore that can also Section 5.2.
be used for matching purposes. The SERIALNUM-ID whitelist is
collated according to vendor trust anchor since serial numbers are
not globally unique.
o The Registrar requests and validates the Voucher from the vendor {
authorized MASA service. "ietf-voucher-request:voucher": {
"nonce": "62a2e7693d82fcda2624de58fb6722e5",
"created-on": "2017-01-01T00:00:00.000Z",
"assertion": "proximity",
"proximity-registrar-cert": "base64encodedvalue=="
}
}
o The Registrar forwards the Voucher to the Pledge when requested. Example (2) The following example illustrates a Registrar generated
voucher-request. The 'prior-signed-voucher-request'
leaf is populated with the Pledge's voucher request
(such as the prior example). See Section 5.4.
o The Registar performs log verifications in addition to local {
authorization checks before accepting optional Pledge device "ietf-voucher-request:voucher": {
enrollment requests. "nonce": "62a2e7693d82fcda2624de58fb6722e5",
"created-on": "2017-01-01T00:00:02.000Z",
"assertion": "proximity",
"idevid-issuer": "base64encodedvalue=="
"serial-number": "JADA123456789"
"prior-signed-voucher": "base64encodedvalue=="
}
}
3.1. Discovery Example (3) The following example illustrates a Registrar generated
voucher-request. The 'prior-signed-voucher-request'
leaf is not populated with the Pledge's voucher request
nor is the nonce leaf. This form might be used by a
Registrar requesting a voucher when the Pledge is
offline or when the Registrar expects to be offline
during deployment. See Section 5.4.
{
"ietf-voucher-request:voucher": {
"created-on": "2017-01-01T00:00:02.000Z",
"assertion": "TBD",
"idevid-issuer": "base64encodedvalue=="
"serial-number": "JADA123456789"
}
}
Example (4) The following example illustrates a Registrar generated
voucher-request. The 'prior-signed-voucher-request'
leaf is not populated with the Pledge's voucher request
because the Pledge did not sign it's own request. This
form might be used when more constrained Pledges are
being deployed. The nonce is populated from the
Pledge's request. See Section 5.4.
{
"ietf-voucher-request:voucher": {
"nonce": "62a2e7693d82fcda2624de58fb6722e5",
"created-on": "2017-01-01T00:00:02.000Z",
"assertion": "proximity",
"idevid-issuer": "base64encodedvalue=="
"serial-number": "JADA123456789"
}
}
3.3. YANG Module
Following is a YANG [RFC7950] module formally extending the
[I-D.ietf-anima-voucher] voucher into the voucher request.
<CODE BEGINS> file "ietf-voucher-request@2017-10-13.yang"
module ietf-voucher-request {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-voucher-request";
prefix "vch";
import ietf-restconf {
prefix rc;
description
"This import statement is only present to access
the yang-data extension defined in RFC 8040.";
reference "RFC 8040: RESTCONF Protocol";
}
import ietf-voucher {
prefix v;
description
"FIXME";
reference "RFC ????: Voucher Profile for Bootstrapping Protocols";
}
organization
"IETF ANIMA Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/anima/>
WG List: <mailto:anima@ietf.org>
Author: Kent Watsen
<mailto:kwatsen@juniper.net>
Author: Max Pritikin
<mailto:pritikin@cisco.com>
Author: Michael Richardson
<mailto:mcr+ietf@sandelman.ca>
Author: Toerless Eckert
<mailto:tte+ietf@cs.fau.de>";
description
"This module... FIXME
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT',
'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in
the module text are to be interpreted as described in RFC 2119.
Copyright (c) 2017 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, is permitted pursuant to, and subject to the license
terms contained in, the Simplified BSD License set forth in Section
4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the RFC
itself for full legal notices.";
revision "2017-10-13" {
description
"Initial version";
reference
"RFC XXXX: Voucher Profile for Bootstrapping Protocols";
}
// Top-level statement
rc:yang-data voucher-request-artifact {
uses voucher-request-grouping;
}
// Grouping defined for future usage
grouping voucher-request-grouping {
description
"Grouping to allow reuse/extensions in future work.";
uses v:voucher-artifact-grouping {
refine "voucher/created-on" {
mandatory false;
}
refine "voucher/pinned-domain-cert" {
mandatory false;
}
augment "voucher" {
description
"Adds leaf nodes appropriate for requesting vouchers.";
leaf prior-signed-voucher-request {
type binary;
description
"If it is necessary to change a voucher, or re-sign and
forward a voucher that was previously provided along a
protocol path, then the previously signed voucher SHOULD be
included in this field.
For example, a pledge might sign a proximity voucher, which
an intermediate registrar then re-signs to make its own
proximity assertion. This is a simple mechanism for a
chain of trusted parties to change a voucher, while
maintaining the prior signature information.
The pledge MUST ignore all prior voucher information when
accepting a voucher for imprinting. Other parties MAY
examine the prior signed voucher information for the
purposes of policy decisions. For example this information
could be useful to a MASA to determine that both pledge and
registrar agree on proximity assertions. The MASA SHOULD
remove all prior-signed-voucher information when signing
a voucher for imprinting so as to minimize the final
voucher size.";
}
leaf proximity-registrar-cert {
type binary;
description
"An X.509 v3 certificate structure as specified by RFC 5280,
Section 4 encoded using the ASN.1 distinguished encoding
rules (DER), as specified in ITU-T X.690.
The first certificate in the Registrar TLS server
certificate_list sequence (see [RFC5246]) presented by
the Registrar to the Pledge. This MUST be populated in a
Pledge's voucher request if the proximity assertion is
populated.";
}
}
}
}
}
<CODE ENDS>
4. Proxy details
The role of the Proxy is to facilitate communications. The Proxy
forwards packets between the Pledge and a Registrar that has been
configured on the Proxy.
The Proxy does not terminate the TLS handshake: it passes streams of
bytes onward without examination.
A proxy MAY assume TLS framing for auditing purposes, but MUST NOT
assume any TLS version.
A Proxy is always assumed even if it is directly integrated into a
Registrar. (In a completely autonomic network, the Registrar MUST
provide proxy functionality so that it can be discovered, and the
network can grow concentrically around the Registrar)
As a result of the Proxy Discovery process in section Section 4.1.1,
the port number exposed by the proxy does not need to be well known,
or require an IANA allocation.
If the Proxy joins an Autonomic Control Plane
([I-D.ietf-anima-autonomic-control-plane]) it SHOULD use Autonomic
Control Plane secured GRASP ([I-D.ietf-anima-grasp]) to discovery the
Registrar address and port. As part of the discovery process, the
proxy mechanism (Circuit Proxy vs IPIP encapsulation) is agreed to
between the Registrar and Join Proxy.
For the IPIP encapsulation methods (described in Appendix C), the
port announced by the Proxy SHOULD be the same as on the registrar in
order for the proxy to remain stateless.
In order to permit the proxy functionality to be implemented on the
maximum variety of devices the chosen mechanism SHOULD use the
minimum amount of state on the proxy device. While many devices in
the ANIMA target space will be rather large routers, the proxy
function is likely to be implemented in the control plane CPU of such
a device, with available capabilities for the proxy function similar
to many class 2 IoT devices.
The document [I-D.richardson-anima-state-for-joinrouter] provides a
more extensive analysis and background of the alternative proxy
methods.
4.1. Pledge discovery of Proxy
The result of discovery is a logical communication with a Registrar, The result of discovery is a logical communication with a Registrar,
through a Proxy. The Proxy is transparent to the Pledge but is through a Proxy. The Proxy is transparent to the Pledge but is
always assumed to exist. always assumed to exist.
To discover the Registrar the Pledge performs the following actions: To discover the Proxy the Pledge performs the following actions:
a. MUST: Obtains a local address using IPv6 methods as described in 1. MUST: Obtains a local address using IPv6 methods as described in
[RFC4862] IPv6 Stateless Address AutoConfiguration. [RFC7217] is [RFC4862] IPv6 Stateless Address AutoConfiguration. Use of
encouraged. Pledges will generally prefer use of IPv6 Link-Local
addresses, and discovery of Proxy will be by Link-Local
mechanisms. IPv4 methods are described in Appendix A
b. MUST: Listen for GRASP M_FLOOD ([I-D.ietf-anima-grasp]) [RFC4941] temporary addresses is encouraged. A new temporary
announcements of the objective: "ACP+Proxy". See section address SHOULD be allocated whenever the discovery process is
Section 3.1.1 for the details of the the objective. The Pledge forced to restart due to failures. Pledges will generally prefer
may listen concurrently for other sources of information, see use of IPv6 Link-Local addresses, and discovery of Proxy will be
by Link-Local mechanisms. IPv4 methods are described in
Appendix A
2. MUST: Listen for GRASP M_FLOOD ([I-D.ietf-anima-grasp])
announcements of the objective: "AN_Proxy". See section
Section 4.1.1 for the details of the objective. The Pledge may
listen concurrently for other sources of information, see
Appendix B. Appendix B.
Once a proxy is discovered the Pledge communicates with a Registrar Once a proxy is discovered the Pledge communicates with a Registrar
through the proxy using the bootstrapping protocol defined in through the proxy using the bootstrapping protocol defined in
Section 3. Section 5.
Each discovery method attempted SHOULD exponentially back-off Each discovery method attempted SHOULD exponentially back-off
attempts (to a maximum of one hour) to avoid overloading the network attempts (to a maximum of one hour) to avoid overloading the network
infrastructure with discovery. The back-off timer for each method infrastructure with discovery. The back-off timer for each method
MUST be independent of other methods. MUST be independent of other methods.
Methods SHOULD be run in parallel to avoid head of queue problems Methods SHOULD be run in parallel to avoid head of queue problems
wherein an attacker running a fake proxy or registrar can operate wherein an attacker running a fake proxy or registrar can operate
protocol actions intentionally slowly. protocol actions intentionally slowly.
Once a connection to a Registrar is established (e.g. establishment Once a connection to a Registrar is established (e.g. establishment
of a TLS session key) there are expectations of more timely of a TLS session key) there are expectations of more timely
responses, see Section 3.2. responses, see Section 5.2.
Once all discovered services are attempted the device SHOULD return Once all discovered services are attempted the device SHOULD return
to listening for GRASP M_FLOOD. It should periodically retry the to listening for GRASP M_FLOOD. It should periodically retry the
vendor specific mechanisms. The Pledge MAY prioritize selection vendor specific mechanisms. The Pledge MAY prioritize selection
order as appropriate for the anticipated environment. order as appropriate for the anticipated environment.
3.1.1. Proxy Discovery Protocol Details 4.1.1. Proxy Grasp announcements
The proxy uses the GRASP M_FLOOD mechanism to announce itself. This A proxy uses the GRASP M_FLOOD mechanism to announce itself. The
announcement is done with the same message as the ACP announcement pledge SHOULD listen for messages of these form. This announcement
detailed in [I-D.ietf-anima-autonomic-control-plane]. can be within the same message as the ACP announcement detailed in
[I-D.ietf-anima-autonomic-control-plane].
proxy-objective = ["Proxy", [ O_IPv6_LOCATOR, ipv6-address, proxy-objective = ["AN_Proxy", [ O_IPv6_LOCATOR, ipv6-address,
transport-proto, port-number ] ] transport-proto, port-number ] ]
ipv6-address - the v6 LL of the proxy ipv6-address - the v6 LL of the proxy
transport-proto - 6, for TCP 17 for UDP transport-proto - 6, for TCP 17 for UDP
port-number - the TCP or UDP port number to find the proxy port-number - the TCP or UDP port number to find the proxy
Figure 5 Figure 5
3.1.2. Registrar Discovery Protocol Details 4.2. CoAP connection to Registrar
A Registrar is typically configured manually. When the Registrar The use of CoAP to connect from Pledge to Registrar is out of scope
joins an Autonomic Control Plane for this document, and may be described in future work.
4.3. HTTPS proxy connection to Registrar
The proxy SHOULD also provide one of: an IPIP encapsulation of HTTP
traffic to the registrar, or a TCP circuit proxy that connects the
Pledge to a Registrar.
When the Proxy provides a circuit proxy to a Registrar the Registrar
MUST accept HTTPS connections.
4.4. Proxy discovery of Registrar
The Registrar SHOULD announce itself so that proxies can find it and
determine what kind of connections can be terminated.
When the Registrar joins an Autonomic Control Plane
([I-D.ietf-anima-autonomic-control-plane]) it MUST respond to GRASP ([I-D.ietf-anima-autonomic-control-plane]) it MUST respond to GRASP
([I-D.ietf-anima-grasp]) M_NEG_SYN message. ([I-D.ietf-anima-grasp]) M_NEG_SYN message.
The registrar responds to discovery messages from the proxy (or GRASP The registrar responds to discovery messages from the proxy (or GRASP
caches between them) as follows: (XXX changed from M_DISCOVERY) caches between them) as follows: (XXX changed from M_DISCOVERY)
objective = ["AN_registrar", F_DISC, 255 ] objective = ["AN_registrar", F_DISC, 255 ]
discovery-message = [M_NEG_SYN, session-id, initiator, objective] discovery-message = [M_NEG_SYN, session-id, initiator, objective]
Figure 6: Registrar Discovery Figure 6: Registrar Discovery
skipping to change at page 19, line 22 skipping to change at page 27, line 37
address given in the locator. address given in the locator.
Registrars MUST accept TCP / UDP traffic on the ports given at the Registrars MUST accept TCP / UDP traffic on the ports given at the
ACP address of the Registrar. If the Registrar supports IPIP ACP address of the Registrar. If the Registrar supports IPIP
tunnelling, it MUST also accept traffic encapsulated with IPIP. tunnelling, it MUST also accept traffic encapsulated with IPIP.
Registrars MUST accept HTTPS/EST traffic on the TCP ports indicated. Registrars MUST accept HTTPS/EST traffic on the TCP ports indicated.
Registrars MAY accept DTLS/CoAP/EST traffic on the UDP in addition to Registrars MAY accept DTLS/CoAP/EST traffic on the UDP in addition to
TCP traffic. TCP traffic.
3.2. Request Voucher from the Registrar 5. Protocol Details
The Pledge MUST initiate BRSKI after boot if it is unconfigured. The
Pledge MUST NOT automatically initiate BRSKI if it has been
configured or is in the process of being configured.
BRSKI is described as extensions to EST [RFC7030] to reduce the
number of TLS connections and crypto operations required on the
Pledge. The Registrar implements the BRSKI REST interface within the
same .well-known URI tree as the existing EST URIs as described in
EST [RFC7030] section 3.2.2. The communication channel between the
Pledge and the Registrar is referred to as "BRSKI-EST" (see
Figure 1).
The communication channel between the Registrar and MASA is similarly
described as extensions to EST within the same ./well-known tree.
For clarity this channel is referred to as "BRSKI-MASA". (See
Figure 1).
MASA URI is "https:// authority "./well-known/est".
BRSKI uses EST message formats for existing operations, uses JSON
[RFC7159] for all new operations defined here, and voucher formats.
While EST section 3.2 does not insist upon use of HTTP 1.1 persistent
connections, BRSKI-EST connections SHOULD use persistent connections.
The intention of this guidance is to ensure the provisional TLS
authentication occurs only once and is properly managed.
Summarized automation extensions for the BRSKI-EST flow are:
o The Pledge provisionally accepts the Registrar certificate during
the TLS handshake as detailed in Section 5.1.
o If the Registrar responds with a redirection to other web origins
the Pledge MUST follow only a single redirection. (EST supports
redirection but does not allow redirections to other web origins
without user input).
o The Registar MAY respond with an HTTP 202 ("the request has been
accepted for processing, but the processing has not been
completed") as described in EST [RFC7030] section 4.2.3 wherein
the client "MUST wait at least the specified 'retry-after' time
before repeating the same request". The Pledge is RECOMMENDED to
provide local feed (blinked LED etc) during this wait cycle if
mechanisms for this are available. To prevent an attacker
Registrar from significantly delaying bootstrapping the Pledge
MUST limit the 'retry-after' time to 60 seconds. To avoid
blocking on a single erroneous Registrar the Pledge MUST drop the
connection after 5 seconds in which there has been no progress on
the TCP connection. It should proceed to other discovered
Registrars if there are any. If there were no other Registrars
discovered, the pledge MAY continue to wait, as long as it is
concurrently listening for new proxy announcements.
o Ideally the Pledge could keep track of the appropriate retry-after
value for any number of outstanding Registrars but this would
involve a large state table on the Pledge. Instead the pledge MAY
ignore the exact retry-after value in favor of a single hard coded
value that takes effect between discovery ([[ProxyDiscovery]])
attempts. A Registrar that is unable to complete the transaction
the first time due to timing reasons will have future chances.
o The Pledge requests and validates a voucher using the new REST
calls described below.
o If necessary the Pledge calls the EST defined /cacerts method to
obtain the domain owners' CA certificate. The pinned-domain-
certificate element from the voucher should validate this
certificate, or be identical to it.
o The Pledge completes authentication of the server certificate as
detailed in Section 5.5.1. This moves the BRSKI-EST TLS
connection out of the provisional state. Optionally, the BRSKI-
EST TLS connection can now be used for EST enrollment.
The extensions for a Registrar (equivalent to EST server) are:
o Client authentication is automated using Initial Device Identity
(IDevID) as per the EST certificate based client authentication.
The subject field's DN encoding MUST include the "serialNumber"
attribute with the device's unique serial number. In the language
of RFC6125 this provides for a SERIALNUM-ID category of identifier
that can be included in a certificate and therefore that can also
be used for matching purposes. The SERIALNUM-ID whitelist is
collated according to vendor trust anchor since serial numbers are
not globally unique.
o The Registrar requests and validates the Voucher from the vendor
authorized MASA service.
o The Registrar forwards the Voucher to the Pledge when requested.
o The Registar performs log verifications in addition to local
authorization checks before accepting optional Pledge device
enrollment requests.
5.1. BRSKI-EST TLS establishment details
The Pledge establishes the TLS connection with the Registrar through
the circuit proxy (see Section 4) but the TLS handshake is with the
Registar. The BRSKI-EST Pledge is the TLS client and the BRSKI-EST
Registrar is the TLS server. All security associations established
are between the Pledge and the Registrar regardless of proxy
operations.
Establishment of the BRSKI-EST TLS connection is as specified in EST
[RFC7030] section 4.1.1 "Bootstrap Distribution of CA Certificates"
[RFC7030] wherein the client is authenticated with the IDevID
certificate, and the EST server (the Registrar) is provisionally
authenticated with a unverified server certificate.
The Pledge maintains a security paranoia concerning the provisional
state, and all data recieved, until a voucher is received and
verified as specified in Section 5.5.1
5.2. Pledge Requests Voucher from the Registrar
When the Pledge bootstraps it makes a request for a Voucher from a When the Pledge bootstraps it makes a request for a Voucher from a
Registrar. Registrar.
This is done with an HTTPS POST using the operation path value of This is done with an HTTPS POST using the operation path value of
"/requestvoucher". "/requestvoucher".
The request media types are: The request media types are:
application/voucherrequest The request is a "YANG-defined JSON application/pkcs7-mime; smime-type=voucher-request The request is a
document that has been signed using a PKCS#7 structure" as "YANG-defined JSON document that has been signed using a PKCS#7
described in [I-D.ietf-anima-voucher] using the JSON encoded structure" as described in Section 3 using the JSON encoding
described in [RFC7951]. Signing the request is RECOMMENDED if the described in [RFC7951]. The Pledge SHOULD sign the request using
Pledge has sufficient processing to perform the crypto operations. the Section 2.3 credential.
Doing so allows the Registrar to forward the Pledge's signed
'proximity' assertion to the MASA as discussed in the security
considerations.
application/unsignedvoucherrequest The request is the "YANG-defined application/json The request is the "YANG-defined JSON document" as
JSON document" but has not been signed. It is the inner JSON described in Section 3 with exception that it is not within a
structure protected only by the TLS client authentication. This PKCS#7 structure. It is protected only by the TLS client
reduces the cryptographic requirements on the Pledge. authentication. This reduces the cryptographic requirements on
the Pledge.
For simplicity the term 'voucher request' is used to refer to either For simplicity the term 'voucher request' is used to refer to either
of these media types. Registrar impementations SHOULD anticipate of these media types. Registrar impementations SHOULD anticipate
future media types but of course will simply fail the request if future media types but of course will simply fail the request if
those types are not yet known. those types are not yet known.
The Pledge populates the voucher request fields as follows: The Pledge populates the voucher request fields as follows:
created-on: Pledges that have a realtime clock are RECOMMENDED to created-on: Pledges that have a realtime clock are RECOMMENDED to
populate this field. This provides additional information to the populate this field. This provides additional information to the
MASA. MASA.
nonce: The voucher request MUST contain a cryptographically strong nonce: The voucher request MUST contain a cryptographically strong
random or pseudo-random number nonce. Doing so ensures random or pseudo-random number nonce. Doing so ensures
Section 2.4 functionality. The nonce MUST NOT be reused for Section 2.5 functionality. The nonce MUST NOT be reused for
multiple bootstrapping attempts. bootstrapping attempts.
assertion: The voucher request MAY contain an assertion of assertion: The voucher request MAY contain an assertion of
"proximity". "proximity".
pinned-domain-cert: In a Pledge voucher request this is the proximity-registrar-cert: In a Pledge voucher request this is the
Registrar certificate as extracted from the TLS handshake (for first certificate in the TLS server 'certificate_list' sequence
example the first certificate in the TLS 'certificate_list' (see [RFC5246]) presented by the Registrar to the Pledge. This
sequence (see [RFC5246]). This MUST be populated in a Pledge's MUST be populated in a Pledge's voucher request if the "proximity"
voucher request if the "proximity" assertion is populated. assertion is populated.
All other fields MAY be ommitted in the voucher request.
An example JSON payload of a voucher request from a Pledge: All other fields MAY be omitted in the voucher request.
{ An example JSON payload of a voucher request from a Pledge is in
"ietf-voucher:voucher": { Section 3.2 Example 1.
"nonce": "62a2e7693d82fcda2624de58fb6722e5",
"created-on": "2017-01-01T00:00:00.000Z",
"assertion": "proximity",
"pinned-domain-cert": "<base64 encoded certificate>"
}
}
The Registrar validates the client identity as described in EST The Registrar validates the client identity as described in EST
[RFC7030] section 3.3.2. If the request is signed the Registrar [RFC7030] section 3.3.2. If the request is signed the Registrar
confirms the 'proximity' asserion and associated 'pinned-domain-cert' confirms the 'proximity' asserion and associated 'proximity-
are correct. The registrar performs authorization as detailed in registrar-cert' are correct. The registrar performs authorization as
[[EDNOTE: UNRESOLVED. See Appendix D "Pledge Authorization"]]. If detailed in [[EDNOTE: UNRESOLVED. See Appendix D "Pledge
these validations fail the Registrar SHOULD respond with an Authorization"]]. If these validations fail the Registrar SHOULD
appropriate HTTP error code. respond with an appropriate HTTP error code.
If authorization is successful the Registrar obtains a voucher from If authorization is successful the Registrar obtains a voucher from
the MASA service (see Section 3.3) and returns that MASA signed the MASA service (see Section 5.4) and returns that MASA signed
voucher to the pledge as described in Section 3.4. voucher to the pledge as described in Section 5.5.
3.3. Request Voucher from MASA 5.3. BRSKI-MASA TLS establishment details
when a Registrar recieves a voucher request from a Pledge it in turn The BRSKI-MASA TLS connection is a 'normal' TLS connection
appropriate for HTTPS REST interfaces. The Registrar initiates the
connection and uses the MASA URL obtained as described in Section 2.7
for RFC6125 authentication of the MASA server.
The primary method of Registrar "authentication" by the MASA is
detailed in Section 5.4. As detailed in Section 8 the MASA might
find it necessary to request additional Registrar authentication.
Registrars MUST be prepared to support TLS client certificate
authentication and HTTP Basic or Digest authentication as described
in RFC7030 for EST clients. Implementors are advised that contacting
the MASA is to establish a secured REST connection with a web service
and that there are a number of authentication models being explored
within the industry. Registrars are RECOMMENDED to fail gracefully
and generate useful administrative notifications or logs in the
advent of unexpected HTTP 401 (Unauthorized) responses from the MASA.
5.4. Registrar Requests Voucher from MASA
When a Registrar receives a voucher request from a Pledge it in turn
requests a voucher from the MASA service. For simplicity this is requests a voucher from the MASA service. For simplicity this is
defined as an optional EST message between a Registrar and an EST defined as an optional EST message between a Registrar and an EST
server running on the MASA service although the Registrar is not server running on the MASA service although the Registrar is not
required to make use of any other EST functionality when required to make use of any other EST functionality when
communicating with the MASA service. (The MASA service MUST properly communicating with the MASA service. (The MASA service MUST properly
reject any EST functionality requests it does not wish to service; a reject any EST functionality requests it does not wish to service; a
requirement that holds for any REST interface). requirement that holds for any REST interface).
This is done with an HTTP POST using the operation path value of This is done with an HTTP POST using the operation path value of
"/requestvoucher". "/requestvoucher".
The request media type is: The request media type is:
application/voucherrequest The request is a "YANG-defined JSON application/pkcs7-mime; smime-type=voucher-request The request is a
document that has been signed using a PKCS#7 structure" as "YANG-defined JSON document that has been signed using a PKCS#7
described in [I-D.ietf-anima-voucher] using the JSON encoded structure" as described in [I-D.ietf-anima-voucher] using the JSON
described in [RFC7951]. The Registrar MUST sign the request. The encoding described in [RFC7951]. The Registrar MUST sign the
entire Registrar certificate chain, up to and including the Domain request. The entire Registrar certificate chain, up to and
CA, MUST be included in the PKCS#7 structure. including the Domain CA, MUST be included in the PKCS#7 structure.
For simplicity the term 'voucher request' is used. MASA For simplicity the term 'voucher request' is used. MASA
impementations SHOULD anticipate future media types but of course impementations SHOULD anticipate future media types but of course
will simply fail the request if those types are not yet known. will simply fail the request if those types are not yet known.
The Registrar populates the voucher request fields as follows: The Registrar populates the voucher request fields as follows:
created-on: Registrars are RECOMMENDED to populate this field. This created-on: Registrars are RECOMMENDED to populate this field. This
provides additional information to the MASA. provides additional information to the MASA.
nonce: The optional nonce value from the Pledge request if desired nonce: The optional nonce value from the Pledge request if desired
(see below). (see below).
serial-number: The serial number of the Pledge the Registrar would serial-number: The serial number of the Pledge the Registrar would
like a voucher for. like a voucher for.
idevid-issuer: The idevid-issuer value from the pledge certificate idevid-issuer: The idevid-issuer value from the pledge certificate
is included to ensure a statistically unique identity. The is included to ensure a statistically unique identity. The
Pledge's serial number is extracted from the X.509 IDevID. See Pledge's serial number is extracted from the X.509 IDevID. See
Section 2.2. Section 2.3.
prior-signed-voucher: If the Pledge provided a signed voucher prior-signed-voucher: If the Pledge provided a signed voucher
request then it SHOULD be included in the voucher request built by request then it SHOULD be included in the voucher request built by
the Registrar. the Registrar. (NOTE: this is the Pledge's complete voucher
request, inclusive of the 'assertion', 'proximity-registrar-cert',
All other fields MAY be ommitted in the voucher request. etc wrapped by the pledge's original PKCS#7 signature).
An example JSON payload of a voucher request from a Registrar:
{
"ietf-voucher:voucher": {
"nonce": "62a2e7693d82fcda2624de58fb6722e5",
"created-on": "2017-01-01T00:00:00.000Z",
"assertion": "proximity"
"idevid-issuer": "<base64 encoded Authority Key Identifier>"
"serial-number": "JADA123456789"
"prior-signed-voucher": "<base64 encode prior voucher request>"
}
}
A Registrar MAY exclude the nonce from the voucher request it submits A Registrar MAY exclude the nonce from the voucher request it submits
to the MASA. Doing so allows the Registrar to request a Voucher when to the MASA. Doing so allows the Registrar to request a Voucher when
the Pledge is offline, or when the Registrar is expected to be the Pledge is offline, or when the Registrar is expected to be
offline when the Pledge is being deployed. These use cases require offline when the Pledge is being deployed. These use cases require
the Registrar to learn the appropriate IDevID SerialNumber field from the Registrar to learn the appropriate IDevID SerialNumber field from
the physical device labeling or from the sales channel (out-of-scope the physical device labeling or from the sales channel (out-of-scope
of this document). If a nonce is not provided the MASA server MUST of this document). If a nonce is not provided the MASA server MUST
authenticate the Registrar as described in EST [RFC7030] section authenticate the Registrar as described in EST [RFC7030] section
3.3.2 to reduce the risk of DDoS attacks and to provide an 3.3.2 to reduce the risk of DDoS attacks and to provide an
authenticated identity as an input to sales channel integration and authenticated identity as an input to sales channel integration and
authorizations (also out-of-scope of this document). authorizations (also out-of-scope of this document).
All other fields MAY be omitted in the voucher request.
Example JSON payloads of voucher requests from a Registrar are in
Section 3.2 Example 2 through 4.
The MASA verifies that the voucher request is internally consistent The MASA verifies that the voucher request is internally consistent
but does not authenticate the domain identity information since the but does not authenticate the registrar certificate since the
domain is not know to the MASA server in advance. The MASA registrar is not know to the MASA server in advance. The MASA
validation checks before issuing a voucher are as follows: validation checks before issuing a voucher are as follows:
Renew for expired voucher: As described in [I-D.ietf-anima-voucher] Renew for expired voucher: As described in [I-D.ietf-anima-voucher]
vouchers are normally short lived to avoid revocation issues. If vouchers are normally short lived to avoid revocation issues. If
the request is for a previous (expired) voucher using the same the request is for a previous (expired) voucher using the same
Registrar (as determined by the Registrar pinned-domain-cert) and Registrar (as determined by the Registrar pinned-domain-cert) and
the MASA has not been informed that the claim is invalid then the the MASA has not been informed that the claim is invalid then the
request for a renewed voucher SHOULD be automatically authorized. request for a renewed voucher SHOULD be automatically authorized.
Voucher signature consistency: The MASA MUST verify that the voucher Voucher signature consistency: The MASA MUST verify that the voucher
skipping to change at page 23, line 21 skipping to change at page 34, line 7
Because the Registar certificate authority is unknown to the MASA Because the Registar certificate authority is unknown to the MASA
in advance this is only an extended consistency check and is not in advance this is only an extended consistency check and is not
required. The maximum lifetime of the voucher issued SHOULD NOT required. The maximum lifetime of the voucher issued SHOULD NOT
exceed the lifetime of the Registrar's revocation validation (for exceed the lifetime of the Registrar's revocation validation (for
example if the Registrar revocation status is indicated in a CRL example if the Registrar revocation status is indicated in a CRL
that is valid for two weeks then that is an appropriate lifetime that is valid for two weeks then that is an appropriate lifetime
for the voucher). for the voucher).
Pledge proximity assertion: The MASA server MAY verify that the Pledge proximity assertion: The MASA server MAY verify that the
Registrar signed voucher includes the 'prior-signed-voucher' field Registrar signed voucher includes the 'prior-signed-voucher' field
populated with a Pledge signed voucher that includes a pinned- populated with a Pledge signed voucher that includes a 'proximity-
domain-cert that is consistent with the Registrar certificate registrar-cert' that is consistent with the certificate the
chain. The MASA server is aware of which Pledge's support signing Registrar used to sign the voucher request. The MASA server is
of their voucher requests and can use this information to confirm aware of which Pledge's support signing of their voucher requests
proximity of the Pledge with the Registrar. and can use this information to confirm proximity of the Pledge
with the Registrar.
The root certificate is extracted from the signature method and used The Registrar certificate chain root certificate is extracted from
to populate the "pinned-domain-cert" of the Voucher being issued. the signature method and used to populate the "pinned-domain-cert" of
The domain ID (e.g. hash of the public key of the domain) is the Voucher being issued. The domain ID (e.g. hash of the public key
extracted from the root certificate and is used to update the audit of the domain) is extracted from the root certificate and is used to
log. update the audit log.
3.4. Voucher Response 5.5. Voucher Response
The voucher response to requests from the Pledge and requests from a The voucher response to requests from the Pledge and requests from a
Registrar are in the same format. A Registrar either caches prior Registrar are in the same format. A Registrar either caches prior
MASA responses or dynamically requests a new Voucher based on local MASA responses or dynamically requests a new Voucher based on local
policy. policy.
If the the join operation is successful, the server response MUST If the join operation is successful, the server response MUST contain
contain an HTTP 200 response code. The server MUST answer with a an HTTP 200 response code. The server MUST answer with a suitable
suitable 4xx or 5xx HTTP [RFC2616] error code when a problem occurs. 4xx or 5xx HTTP [RFC2616] error code when a problem occurs. The
The response data from the MASA server MUST be a plaintext human- response data from the MASA server MUST be a plaintext human-readable
readable (ASCII, english) error message containing explanatory (ASCII, english) error message containing explanatory information
information describing why the request was rejected. describing why the request was rejected.
Response media type: application/voucher+cms A 403 (Forbidden) response is appropriate if the voucher request is
not signed correctly, stale, or if the pledge has another outstanding
voucher which can not be overridden.
A 404 (Not Found) response is appropriate when the request is for a
device which is not known to the MASA.
A 406 (Not Acceptable) response is appropriate if a voucher of the
desired type, or using the desired algorithms (as indicated by the
Accept: headers, and algorithms used in the signature) can not be
issued, such as because the MASA knows the pledge can not process
that type.
A 415 (Unsupported Media Type) response is approriate for a request
that has a voucher encoding that is not understood.
The response media type is:
application/pkcs7-mime; smime-type=voucher The response is a "YANG-
defined JSON document that has been signed using a PKCS#7
structure" as described in [I-D.ietf-anima-voucher] using the JSON
encoded described in [RFC7951]. The MASA MUST sign the request.
The syntactic details of vouchers are described in detail in The syntactic details of vouchers are described in detail in
[I-D.ietf-anima-voucher]. For example, the voucher consists of: [I-D.ietf-anima-voucher]. For example, the voucher consists of:
{ {
"ietf-voucher:voucher": { "ietf-voucher:voucher": {
"nonce": "62a2e7693d82fcda2624de58fb6722e5", "nonce": "62a2e7693d82fcda2624de58fb6722e5",
"assertion": "logging" "assertion": "logging"
"pinned-domain-cert": "<base64 encoded certificate>" "pinned-domain-cert": "base64encodedvalue=="
"serial-number": "JADA123456789" "serial-number": "JADA123456789"
} }
} }
The Pledge verifies the signed voucher using the manufacturer The Pledge verifies the signed voucher using the manufacturer
installed trust anchor associated with the vendor's selected installed trust anchor associated with the vendor's selected
Manufacturer Authorized Signing Authority. Manufacturer Authorized Signing Authority.
The 'pinned-domain-cert' element of the voucher contains the domain The 'pinned-domain-cert' element of the voucher contains the domain
CA's public key. The Pledge MUST use the 'pinned-domain-cert' trust CA's public key. The Pledge MUST use the 'pinned-domain-cert' trust
anchor to immediately complete authentication of the provisional TLS anchor to immediately complete authentication of the provisional TLS
connection. connection.
The Pledge MUST be prepared to parse and fail gracefully from an The Pledge MUST be prepared to parse and fail gracefully from a
Voucher response that does not contain a 'pinned-domain-cert' field. Voucher response that does not contain a 'pinned-domain-cert' field.
The Pledge MUST be prepared to ignore additional fields it does not The Pledge MUST be prepared to ignore additional fields it does not
recognize. recognize.
3.4.1. Completing authentication of Provisional TLS connection 5.5.1. Completing authentication of Provisional TLS connection
If a Registrar's credentials can not be verified using the pinned- If a Registrar's credentials can not be verified using the pinned-
domain-cert trust anchor from the voucher then the TLS connection is domain-cert trust anchor from the voucher then the TLS connection is
immediately discarded and the Pledge abandons attempts to bootstrap immediately discarded and the Pledge abandons attempts to bootstrap
with this discovered registrar. The pledge SHOULD send voucher with this discovered registrar. The pledge SHOULD send voucher
status telemetry (described below) before closing the TLS connection. status telemetry (described below) before closing the TLS connection.
The pledge MUST attempt to enroll using any other proxies it has The pledge MUST attempt to enroll using any other proxies it has
found. It SHOULD return to the same proxy again after attempting found. It SHOULD return to the same proxy again after attempting
with other proxies. Attempts should be attempted in the exponential with other proxies. Attempts should be attempted in the exponential
backoff described earlier. Attempts SHOULD be repeated as failure backoff described earlier. Attempts SHOULD be repeated as failure
may be the result of a temporary inconsistently (an inconsistently may be the result of a temporary inconsistently (an inconsistently
rolled Registrar key, or some other mis-configuration). The rolled Registrar key, or some other mis-configuration). The
inconsistently could also be the result an active MITM attack on the inconsistently could also be the result an active MITM attack on the
EST connection. EST connection.
The Registrar MUST use a certificate that chains to the pinned- The Registrar MUST use a certificate that chains to the pinned-
domain-cert as its TLS server certificate. domain-cert as its TLS server certificate.
The Pledge's PKIX path validation of a Registrar certificate's The Pledge's PKIX path validation of a Registrar certificate's
validity period information is as described in Section 2.4. Once the validity period information is as described in Section 2.5. Once the
PKIX path validation is successful the TLS connection is no longer PKIX path validation is successful the TLS connection is no longer
provisional. provisional.
The pinned-domain-cert is installed as an Explicit Trust Anchor for The pinned-domain-cert is installed as an Explicit Trust Anchor for
future operations. It can therefore can be used to authenticate any future operations. It can therefore can be used to authenticate any
dynamically discovered EST server that contain the id-kp-cmcRA dynamically discovered EST server that contain the id-kp-cmcRA
extended key usage extension as detailed in EST RFC7030 section extended key usage extension as detailed in EST RFC7030 section
3.6.1; but to reduce system complexity the Pledge SHOULD avoid 3.6.1; but to reduce system complexity the Pledge SHOULD avoid
additional discovery operations. Instead the Pledge SHOULD additional discovery operations. Instead the Pledge SHOULD
communicate directly with the Registrar as the EST server. The ' communicate directly with the Registrar as the EST server. The '
pinned-domain-cert' is not a complete distribution of the EST section pinned-domain-cert' is not a complete distribution of the EST section
4.1.3 CA Certificate Response which is an additional justification 4.1.3 CA Certificate Response which is an additional justification
for the recommendation to proceed with EST key management operations. for the recommendation to proceed with EST key management operations.
Once a full CA Certificate Response is obtained it is more Once a full CA Certificate Response is obtained it is more
authoritative for the domain than the limited 'pinned-domain-cert' authoritative for the domain than the limited 'pinned-domain-cert'
response.' response.'
3.5. Voucher Status Telemetry 5.6. Voucher Status Telemetry
The domain is expected to provide indications to the system The domain is expected to provide indications to the system
administrators concerning device lifecycle status. To facilitate administrators concerning device lifecycle status. To facilitate
this it needs telemetry information concerning the device's status. this it needs telemetry information concerning the device's status.
To indicate Pledge status regarding the Voucher the client SHOULD To indicate Pledge status regarding the Voucher, the pledge MUST post
post a status message. a status message.
The posted data media type: application/json The posted data media type: application/json
The client HTTP POSTs the following to the server at the EST well The client HTTP POSTs the following to the server at the EST well
known URI /voucher_status. The Status field indicates if the Voucher known URI /voucher_status. The Status field indicates if the Voucher
was acceptable. If it was not acceptable the Reason string indicates was acceptable. If it was not acceptable the Reason string indicates
why. In the failure case this message is being sent to an why. In the failure case this message is being sent to an
unauthenticated, potentially malicious Registrar and therefore the unauthenticated, potentially malicious Registrar and therefore the
Reason string SHOULD NOT provide information beneficial to an Reason string SHOULD NOT provide information beneficial to an
attacker. The operational benefit of this telemetry information is attacker. The operational benefit of this telemetry information is
balanced against the operational costs of not recording that an balanced against the operational costs of not recording that an
Voucher was ignored by a client the registar expected to continue Voucher was ignored by a client the registar expected to continue
joining the domain. joining the domain.
{ {
"version":"1", "version":"1",
"Status":FALSE /* TRUE=Success, FALSE=Fail" "Status":FALSE /* TRUE=Success, FALSE=Fail"
"Reason":"Informative human readable message" "Reason":"Informative human readable message"
"reason-context": { additional JSON }
} }
The server SHOULD respond with an HTTP 200 but MAY simply fail with The server SHOULD respond with an HTTP 200 but MAY simply fail with
an HTTP 404 error. The client ignores any response. Within the an HTTP 404 error. The client ignores any response. Within the
server logs the server SHOULD capture this telemetry information. server logs the server SHOULD capture this telemetry information.
3.6. MASA authorization log Request The reason-context attribute is an arbitrary JSON object (literal
value or hash of values) which provides additional information
specific to this pledge. The contents of this field are not subject
to standardization."
A registrar requests the MASA authorization log from the MASA service Additional standard responses MAY be added via Specification
using this EST extension. If a device had previously registered with Required.
another domain, a Registrar of that domain would show in the log.
5.7. MASA authorization log Request
After receiving the voucher status telemetry Section 5.6, the
Registrar SHOULD request the MASA authorization log from the MASA
service using this EST extension. If a device had previously
registered with another domain, a Registrar of that domain would show
in the log.
This is done with an HTTP GET using the operation path value of This is done with an HTTP GET using the operation path value of
"/requestauditlog". "/requestauditlog".
The registrar MUST HTTP POSTs the same Voucher Request as when The registrar MUST HTTP POSTs the same Voucher Request as when
requesting a Voucher. It is posted to the /requestauditlog URI requesting a Voucher. It is posted to the /requestauditlog URI
instead. The "idevid-issuer" and "serial-number" informs the MASA instead. The "idevid-issuer" and "serial-number" informs the MASA
server which log is requested so the appropriate log can be prepared server which log is requested so the appropriate log can be prepared
for the response. Using the same media type and message minimizes for the response. Using the same media type and message minimizes
cryptographic and message operations although it results in cryptographic and message operations although it results in
additional network traffic. The relying MASA server implementation additional network traffic. The relying MASA server implementation
MAY leverage internal state to associate this request with the MAY leverage internal state to associate this request with the
original, and by now already validated, voucher request so as to original, and by now already validated, voucher request so as to
avoid an extra crypto validation. avoid an extra crypto validation.
Request media type: application/voucherrequest+cms The request media type is:
3.7. MASA authorization log Response application/pkcs7-mime; smime-type=voucher-request The request is a
"YANG-defined JSON document that has been signed using a PKCS#7
structure" as described in Section 3 using the JSON encoded
described in [RFC7951]. The Registrar MUST sign the request. The
entire Registrar certificate chain, up to and including the Domain
CA, MUST be included in the PKCS#7 structure.
5.7.1. MASA authorization log Response
A log data file is returned consisting of all log entries. For A log data file is returned consisting of all log entries. For
example: example:
{ {
"version":"1", "version":"1",
"events":[ "events":[
{ {
"date":"<date/time of the entry>", "date":"<date/time of the entry>",
"domainID":"<domainID as extracted from the domain CA certificate "domainID":"<domainID as extracted from the domain CA certificate
skipping to change at page 27, line 29 skipping to change at page 39, line 10
This document specifies a simple log format as provided by the MASA This document specifies a simple log format as provided by the MASA
service to the registar. This format could be improved by service to the registar. This format could be improved by
distributed consensus technologies that integrate vouchers with a distributed consensus technologies that integrate vouchers with a
technologies such as block-chain or hash trees or the like. Doing so technologies such as block-chain or hash trees or the like. Doing so
is out of the scope of this document but are anticipated improvements is out of the scope of this document but are anticipated improvements
for future work. As such, the Registrar client SHOULD anticipate new for future work. As such, the Registrar client SHOULD anticipate new
kinds of responses, and SHOULD provide operator controls to indicate kinds of responses, and SHOULD provide operator controls to indicate
how to process unknown responses. how to process unknown responses.
3.8. EST Integration for PKI bootstrapping 5.8. EST Integration for PKI bootstrapping
This section describes EST extensions necessary to enable fully
automated bootstrapping. Although the Voucher request/response
structure members "idevid-issuer" and "pinned-domain-cert" are
specific to PKI bootstrapping these are the only PKI specific aspects
of the extensions and future voucher definitions might replace them
with non-PKI fields.
Once the Voucher is received, as specified in this document, the
client has sufficient information to leverage the existing
communication channel with a Registrar to continue an EST RFC7030
enrollment. The voucher provides an automated mechanism for the
"Bootstrap Distribution of CA Certificates" described in [RFC7030]
section 4.1.1 wherein the Pledge "MUST [...]. engage a human user to
authorize the CA certificate using out-of-band" information".
Instead the Pledge now can automate this process using the voucher
provided "pinned-domain-cert".
The Pledge SHOULD use the existing current TLS connection to proceed The Pledge SHOULD follow the BRSKI operations with EST enrollment
with EST enrollment, thus reducing the total amount of cryptographic
and round trip operations required during bootstrapping. After
voucher verification the Pledge continues with EST enrollment
operations including "CA Certificates Request", "CSR Attributes" and operations including "CA Certificates Request", "CSR Attributes" and
"Client Certificate Request" or "Server-Side Key Generation" etc. "Client Certificate Request" or "Server-Side Key Generation" etc.
This is a relatively seamless integration since BRSKI REST calls
provide an automated alternative to the manual bootstrapping method
described in [RFC7030]. As noted above, use of HTTP 1.1 persistent
connections simplifies the Pledge state machine.
The Pledge is RECOMMENDED to implement the following EST automation The Pledge is also RECOMMENDED to implement the following EST
extensions. They supplement the RFC7030 EST to better support automation extensions. They supplement the RFC7030 EST to better
automated devices that do not have an end user. support automated devices that do not have an end user.
3.8.1. EST Distribution of CA Certificates Although EST allows clients to obtain multiple certificates by
sending multiple CSR requests BRSKI mandates use of the CSR
Attributes request and mandates that the Registrar validate the CSR
against the expected attributes. This implies that client requests
will "look the same" and therefore result in a single logical
certificate being issued even if the client were to make multiple
requests. Registrars MAY contain more complex logic but doing so is
out-of-scope of this specification. BRSKI does not signal any
enhancement or restriction to this capability. Pledges that require
multiple certificates could establish direct EST connections to the
Registrar.
5.8.1. EST Distribution of CA Certificates
The Pledge MUST request the full EST Distribution of CA Certificates The Pledge MUST request the full EST Distribution of CA Certificates
message. See RFC7030, section 4.1. message. See RFC7030, section 4.1.
This ensures that the Pledge has the complete set of current CA This ensures that the Pledge has the complete set of current CA
certificates beyond the domainCAcert (see Section 3.4 for a certificates beyond the pinned-domain-cert (see Section 5.5.1 for a
discussion of the limitations). Although these restrictions are discussion of the limitations inherent in having a single certificate
acceptable for a Registrar integrated with initial bootstrapping they instead of a full CA Certificates response). Although these
are not appropriate for ongoing PKIX end entity certificate limitations are acceptable during initial bootstrapping they are not
validation. appropriate for ongoing PKIX end entity certificate validation.
3.8.2. EST CSR Attributes 5.8.2. EST CSR Attributes
Automated bootstrapping occurs without local administrative Automated bootstrapping occurs without local administrative
configuration of the Pledge. In some deployments its plausible that configuration of the Pledge. In some deployments its plausible that
the Pledge generates a certificate request containing only identity the Pledge generates a certificate request containing only identity
information known to the Pledge (essentially the X.509 IDevID information known to the Pledge (essentially the X.509 IDevID
information) and ultimately receives a certificate containing domain information) and ultimately receives a certificate containing domain
specific identity information. Conceptually the CA has complete specific identity information. Conceptually the CA has complete
control over all fields issued in the end entity certificate. control over all fields issued in the end entity certificate.
Realistically this is operationally difficult with the current status Realistically this is operationally difficult with the current status
of PKI certificate authority deployments where the CSR is submitted of PKI certificate authority deployments where the CSR is submitted
skipping to change at page 29, line 19 skipping to change at page 41, line 5
"ACP information" field. See "ACP information" field. See
[I-D.ietf-anima-autonomic-control-plane] for more details. [I-D.ietf-anima-autonomic-control-plane] for more details.
The Registar MUST also confirm the resulting CSR is formatted as The Registar MUST also confirm the resulting CSR is formatted as
indicated before forwarding the request to a CA. If the Registar is indicated before forwarding the request to a CA. If the Registar is
communicating with the CA using a protocol like full CMC which communicating with the CA using a protocol like full CMC which
provides mechanisms to override the CSR attributes, then these provides mechanisms to override the CSR attributes, then these
mechanisms MAY be used even if the client ignores CSR Attribute mechanisms MAY be used even if the client ignores CSR Attribute
guidance. guidance.
3.8.3. EST Client Certificate Request 5.8.3. EST Client Certificate Request
The Pledge MUST request a new client certificate. See RFC7030, The Pledge MUST request a new client certificate. See RFC7030,
section 4.2. section 4.2.
3.8.4. Enrollment Status Telemetry 5.8.4. Enrollment Status Telemetry
For automated bootstrapping of devices the adminstrative elements For automated bootstrapping of devices the adminstrative elements
providing bootstrapping also provide indications to the system providing bootstrapping also provide indications to the system
administrators concerning device lifecycle status. This might administrators concerning device lifecycle status. This might
include information concerning attempted bootstrapping messages seen include information concerning attempted bootstrapping messages seen
by the client, MASA provides logs and status of credential by the client, MASA provides logs and status of credential
enrollment. The EST protocol assumes an end user and therefore does enrollment. The EST protocol assumes an end user and therefore does
not include a final success indication back to the server. This is not include a final success indication back to the server. This is
insufficient for automated use cases. insufficient for automated use cases.
skipping to change at page 30, line 4 skipping to change at page 41, line 38
enrollment failed. The SubjectKeyIdentifier field MUST be included enrollment failed. The SubjectKeyIdentifier field MUST be included
if the enrollment attempt was for a keypair that is locally known to if the enrollment attempt was for a keypair that is locally known to
the client. If EST /serverkeygen was used and failed then the field the client. If EST /serverkeygen was used and failed then the field
is omitted from the status telemetry. is omitted from the status telemetry.
In the case of a SUCCESS the Reason string is omitted. The In the case of a SUCCESS the Reason string is omitted. The
SubjectKeyIdentifier is included so that the server can record the SubjectKeyIdentifier is included so that the server can record the
successful certificate distribution. successful certificate distribution.
Status media type: application/json Status media type: application/json
The client HTTP POSTs the following to the server at the new EST well The client HTTP POSTs the following to the server at the new EST well
known URI /enrollstatus. known URI /enrollstatus.
{ {
"version":"1", "version":"1",
"Status":TRUE /* TRUE=Success, FALSE=Fail" "Status":TRUE /* TRUE=Success, FALSE=Fail"
"Reason":"Informative human readable message" "Reason":"Informative human readable message"
"SubjectKeyIdentifier":"<base64 encoded subjectkeyidentifier for the "reason-context": "Additional information"
enrollment that failed>" }
}
The server SHOULD respond with an HTTP 200 but MAY simply fail with The server SHOULD respond with an HTTP 200 but MAY simply fail with
an HTTP 404 error. an HTTP 404 error.
Within the server logs the server MUST capture if this message was Within the server logs the server MUST capture if this message was
received over an TLS session with a matching client certificate. received over an TLS session with a matching client certificate.
This allows for clients that wish to minimize their crypto operations This allows for clients that wish to minimize their crypto operations
to simply POST this response without renegotiating the TLS session - to simply POST this response without renegotiating the TLS session -
at the cost of the server not being able to accurately verify that at the cost of the server not being able to accurately verify that
enrollment was truly successful. enrollment was truly successful.
3.8.5. EST over CoAP 5.8.5. EST over CoAP
This document describes extensions to EST for the purposes of This document describes extensions to EST for the purposes of
bootstrapping of remote key infrastructures. Bootstrapping is bootstrapping of remote key infrastructures. Bootstrapping is
relevant for CoAP enrollment discussions as well. The defintion of relevant for CoAP enrollment discussions as well. The defintion of
EST and BRSKI over CoAP is not discussed within this document beyond EST and BRSKI over CoAP is not discussed within this document beyond
ensuring proxy support for CoAP operations. Instead it is ensuring proxy support for CoAP operations. Instead it is
anticipated that a definition of CoAP mappings will occur in anticipated that a definition of CoAP mappings will occur in
subsequent documents such as [I-D.vanderstok-ace-coap-est] and that subsequent documents such as [I-D.vanderstok-ace-coap-est] and that
CoAP mappings for BRSKI will be discussed either there or in future CoAP mappings for BRSKI will be discussed either there or in future
work. work.
4. Reduced security operational modes 6. Reduced security operational modes
A common requirement of bootstrapping is to support less secure A common requirement of bootstrapping is to support less secure
operational modes for support specific use cases. The following operational modes for support specific use cases. The following
sections detail specific ways that the Pledge, Registrar and MASA can sections detail specific ways that the Pledge, Registrar and MASA can
be configured to run in a less secure mode for the indicated reasons. be configured to run in a less secure mode for the indicated reasons.
4.1. Trust Model 6.1. Trust Model
+--------+ +---------+ +------------+ +------------+ +--------+ +---------+ +------------+ +------------+
| Pledge | | Circuit | | Domain | | Vendor | | Pledge | | Circuit | | Domain | | Vendor |
| | | Proxy | | Registrar | | Service | | | | Proxy | | Registrar | | Service |
| | | | | | | (Internet | | | | | | | | (Internet |
+--------+ +---------+ +------------+ +------------+ +--------+ +---------+ +------------+ +------------+
Figure 10 Figure 10
Pledge: The Pledge could be compromised and providing an attack Pledge: The Pledge could be compromised and providing an attack
vector for malware. The entity is trusted to only imprint using vector for malware. The entity is trusted to only imprint using
skipping to change at page 31, line 37 skipping to change at page 43, line 18
accurately log all claim attempts and to provide authoritative log accurately log all claim attempts and to provide authoritative log
information to Registrars. The MASA does not know which devices information to Registrars. The MASA does not know which devices
are associated with which domains. These claims could be are associated with which domains. These claims could be
strengthened by using cryptographic log techniques to provide strengthened by using cryptographic log techniques to provide
append only, cryptographic assured, publicly auditable logs. append only, cryptographic assured, publicly auditable logs.
Current text provides only for a trusted vendor. Current text provides only for a trusted vendor.
Vendor Service, Ownership Validation: This form of vendor service is Vendor Service, Ownership Validation: This form of vendor service is
trusted to accurately know which device is owned by which domain. trusted to accurately know which device is owned by which domain.
4.2. Pledge security reductions 6.2. Pledge security reductions
The Pledge can choose to accept vouchers using less secure methods. The Pledge can choose to accept vouchers using less secure methods.
These methods enable offline and emergency (touch based) deployment These methods enable offline and emergency (touch based) deployment
use cases: use cases:
1. The Pledge MUST accept nonceless vouchers. This allows for 1. The Pledge MUST accept nonceless vouchers. This allows for
offline use cases. Logging and validity periods address the offline use cases. Logging and validity periods address the
inherent security considerations of supporting these use cases. inherent security considerations of supporting these use cases.
2. The Pledge MAY support "trust on first use" for physical 2. The Pledge MAY support "trust on first use" for physical
skipping to change at page 32, line 19 skipping to change at page 44, line 5
available via local configuration or physical presence methods to available via local configuration or physical presence methods to
ensure new entities can always be deployed even when autonomic ensure new entities can always be deployed even when autonomic
methods fail. This allows for unsecured imprint. methods fail. This allows for unsecured imprint.
It is RECOMMENDED that "trust on first use" or skipping voucher It is RECOMMENDED that "trust on first use" or skipping voucher
validation only be available if hardware assisted Network Endpoint validation only be available if hardware assisted Network Endpoint
Assessment [RFC5209] is supported. This recommendation ensures that Assessment [RFC5209] is supported. This recommendation ensures that
domain network monitoring can detect innappropriate use of offline or domain network monitoring can detect innappropriate use of offline or
emergency deployment procedures. emergency deployment procedures.
4.3. Registrar security reductions 6.3. Registrar security reductions
A Registrar can choose to accept devices using less secure methods. A Registrar can choose to accept devices using less secure methods.
These methods are acceptable when low security models are needed, as These methods are acceptable when low security models are needed, as
the security decisions are being made by the local administrator, but the security decisions are being made by the local administrator, but
they MUST NOT be the default behavior: they MUST NOT be the default behavior:
1. A registrar MAY choose to accept all devices, or all devices of a 1. A registrar MAY choose to accept all devices, or all devices of a
particular type, at the administrator's discretion. This could particular type, at the administrator's discretion. This could
occur when informing all Registrars of unique identifiers of new occur when informing all Registrars of unique identifiers of new
entities might be operationally difficult. entities might be operationally difficult.
2. A registrar MAY choose to accept devices that claim a unique 2. A registrar MAY choose to accept devices that claim a unique
identity without the benefit of authenticating that claimed identity without the benefit of authenticating that claimed
identity. This could occur when the Pledge does not include an identity. This could occur when the Pledge does not include an
X.509 IDevID factory installed credential. New Entities without X.509 IDevID factory installed credential. New Entities without
an X.509 IDevID credential MAY form the Section 3.2 request using an X.509 IDevID credential MAY form the Section 5.2 request using
the Section 3.3 format to ensure the Pledge's serial number the Section 5.4 format to ensure the Pledge's serial number
information is provided to the Registar (this includes the IDevID information is provided to the Registar (this includes the IDevID
AuthorityKeyIdentifier value which would be statically configured AuthorityKeyIdentifier value which would be statically configured
on the Pledge). The Pledge MAY refuse to provide a TLS client on the Pledge). The Pledge MAY refuse to provide a TLS client
certificate (as one is not available). The Pledge SHOULD support certificate (as one is not available). The Pledge SHOULD support
HTTP-based or certificate-less TLS authentication as described in HTTP-based or certificate-less TLS authentication as described in
EST RFC7030 section 3.3.2. A Registrar MUST NOT accept EST RFC7030 section 3.3.2. A Registrar MUST NOT accept
unauthenticated New Entities unless it has been configured to do unauthenticated New Entities unless it has been configured to do
so by an administrator that has verified that only expected new so by an administrator that has verified that only expected new
entities can communicate with a Registrar (presumably via a entities can communicate with a Registrar (presumably via a
physically secured perimeter). physically secured perimeter).
skipping to change at page 33, line 12 skipping to change at page 44, line 46
then be transmitted to the Registrar and stored until they are then be transmitted to the Registrar and stored until they are
needed during bootstrapping operations. This is for use cases needed during bootstrapping operations. This is for use cases
where target network is protected by an air gap and therefore can where target network is protected by an air gap and therefore can
not contact the MASA service during Pledge deployment. not contact the MASA service during Pledge deployment.
4. A registrar MAY ignore unrecognized nonce-less log entries. This 4. A registrar MAY ignore unrecognized nonce-less log entries. This
could occur when used equipment is purchased with a valid history could occur when used equipment is purchased with a valid history
being deployed in air gap networks that required permanent being deployed in air gap networks that required permanent
Vouchers. Vouchers.
4.4. MASA security reductions 6.4. MASA security reductions
Lower security modes chosen by the MASA service effect all device Lower security modes chosen by the MASA service effect all device
deployments unless bound to the specific device identities. In which deployments unless bound to the specific device identities. In which
case these modes can be provided as additional features for specific case these modes can be provided as additional features for specific
customers. The MASA service can choose to run in less secure modes customers. The MASA service can choose to run in less secure modes
by: by:
1. Not enforcing that a nonce is in the Voucher. This results in 1. Not enforcing that a nonce is in the Voucher. This results in
distribution of Voucher that never expires and in effect makes distribution of Voucher that never expires and in effect makes
the Domain an always trusted entity to the Pledge during any the Domain an always trusted entity to the Pledge during any
subsequent bootstrapping attempts. That this occurred is subsequent bootstrapping attempts. That this occurred is
captured in the log information so that the Domain registrar can captured in the log information so that the Registrar can make
make appropriate security decisions when a Pledge joins the appropriate security decisions when a Pledge joins the Domain.
Domain. This is useful to support use cases where Registrars This is useful to support use cases where Registrars might not be
might not be online during actual device deployment. Because online during actual device deployment. Because this results in
this results in long lived Voucher and does not require the proof long lived Voucher and does not require the proof that the device
that the device is online this is only accepted when the is online this is only accepted when the Registrar is
Registrar is authenticated by the MASA server and authorized to authenticated by the MASA server and authorized to provide this
provide this functionality. The MASA server is RECOMMENDED to functionality. The MASA server is RECOMMENDED to use this
use this functionality only in concert with an enhanced level of functionality only in concert with an enhanced level of ownership
ownership tracking (out-of-scope). If the Pledge device is known tracking (out-of-scope). If the Pledge device is known to have a
to have a real-time-clock that is set from the factory use of a real-time-clock that is set from the factory use of a voucher
voucher validity period is RECOMMENDED. validity period is RECOMMENDED.
2. Not verifying ownership before responding with an Voucher. This 2. Not verifying ownership before responding with an Voucher. This
is expected to be a common operational model because doing so is expected to be a common operational model because doing so
relieves the vendor providing MASA services from having to track relieves the vendor providing MASA services from having to track
ownership during shipping and supply chain and allows for a very ownership during shipping and supply chain and allows for a very
low overhead MASA service. A Registrar uses the audit log low overhead MASA service. A Registrar uses the audit log
information as a defense in depth strategy to ensure that this information as a defense in depth strategy to ensure that this
does not occur unexpectedly (for example when purchasing new does not occur unexpectedly (for example when purchasing new
equipment the Registrar would throw an error if any audit log equipment the Registrar would throw an error if any audit log
information is reported). The MASA should verify the 'prior- information is reported). The MASA should verify the 'prior-
signed-voucher' information for Pledge's that support that signed-voucher' information for Pledge's that support that
functionality. This provides a proof-of-proximity check that functionality. This provides a proof-of-proximity check that
reduces the need for ownership verification. reduces the need for ownership verification.
5. IANA Considerations 7. IANA Considerations
5.1. PKIX Registry This document requests the following Parameter Values for the "smime-
type" Parameters:
o voucher-request
o voucher
7.1. PKIX Registry
IANA is requested to register the following:
This document requests a number for id-mod-MASAURLExtn2016(TBD) from This document requests a number for id-mod-MASAURLExtn2016(TBD) from
the pkix(7) id-mod(0) Registry. [[EDNOTE: fix names]] the pkix(7) id-mod(0) Registry. [[EDNOTE: fix names]]
This document requests a number from the id-pe registry for id-pe- This document requests a number from the id-pe registry for id-pe-
masa-url. XXX masa-url. XXX
6. Security Considerations 7.2. MIME
Type name:
Subtype name:
Required parameters:
Optional parameters:
Encoding considerations:
Security considerations:
Interoperability considerations:
Published specification:
Applications that use this media type:
Fragment identifier considerations:
Additional information:
Deprecated alias names for this type:
Magic number(s):
File extension(s):
Macintosh file type code(s):
Person and email address to contact for further information:
Intended usage: LIMITED USED
Restrictions on usage:
Author:
Change controller:
Provisional registration? (standards tree only):
7.3. Voucher Status Telemetry
IANA is requested to create a registry entitled: _Voucher Status
Telemetry Attributes_. New items can be added using the
Specification Required. The following items are to be in the initial
registration, with this document as the reference:
o version
o Status
o Reason
o reason-context
8. Security Considerations
There are uses cases where the MASA could be unavailable or There are uses cases where the MASA could be unavailable or
uncooperative to the Registrar. They include planned and unplanned uncooperative to the Registrar. They include planned and unplanned
network partitions, changes to MASA policy, or other instances where network partitions, changes to MASA policy, or other instances where
MASA policy rejects a claim. These introduce an operational risk to MASA policy rejects a claim. These introduce an operational risk to
the Registrar owner that MASA/vendor behavior might limit the ability the Registrar owner that MASA/vendor behavior might limit the ability
to re-boostrap a Pledge device. For example this might be an issue to re-boostrap a Pledge device. For example this might be an issue
during disaster recovery. This risk can be mitigated by Registrars during disaster recovery. This risk can be mitigated by Registrars
that request and maintain long term copies of "nonceless" Vouchers. that request and maintain long term copies of "nonceless" Vouchers.
In that way they are guaranteed to be able to repeat bootstrapping In that way they are guaranteed to be able to repeat bootstrapping
skipping to change at page 35, line 24 skipping to change at page 48, line 29
To facilitate logging and administrative oversight the Pledge reports To facilitate logging and administrative oversight the Pledge reports
on Voucher parsing status to the Registrar. In the case of a failure on Voucher parsing status to the Registrar. In the case of a failure
this information is informative to a potentially malicious Registar this information is informative to a potentially malicious Registar
but this is RECOMMENDED anyway because of the operational benefits of but this is RECOMMENDED anyway because of the operational benefits of
an informed administrator in cases where the failure is indicative of an informed administrator in cases where the failure is indicative of
a problem. a problem.
To facilitate truely limited clients EST RFC7030 section 3.3.2 To facilitate truely limited clients EST RFC7030 section 3.3.2
requirements that the client MUST support a client authentication requirements that the client MUST support a client authentication
model have been reduced in Section 4 to a statement that the model have been reduced in Section 6 to a statement that the
Registrar "MAY" choose to accept devices that fail cryptographic Registrar "MAY" choose to accept devices that fail cryptographic
authentication. This reflects current (poor) practices in shipping authentication. This reflects current (poor) practices in shipping
devices without a cryptographic identity that are NOT RECOMMENDED. devices without a cryptographic identity that are NOT RECOMMENDED.
During the provisional period of the connection all HTTP header and During the provisional period of the connection all HTTP header and
content data MUST treated as untrusted data. HTTP libraries are content data MUST treated as untrusted data. HTTP libraries are
regularly exposed to non-secured HTTP traffic: mature libraries regularly exposed to non-secured HTTP traffic: mature libraries
should not have any problems. should not have any problems.
Pledge's might chose to engage in protocol operations with multiple Pledge's might chose to engage in protocol operations with multiple
discovered Registrars in parallel. As noted above they will only do discovered Registrars in parallel. As noted above they will only do
so with distinct nonce values, but the end result could be multple so with distinct nonce values, but the end result could be multple
voucher's issued from the MASA if all registrars attempt to claim the voucher's issued from the MASA if all registrars attempt to claim the
device. This is not a failure and the Pledge choses whichever device. This is not a failure and the Pledge choses whichever
voucher to accept based on internal logic. The Registrar's verifying voucher to accept based on internal logic. The Registrar's verifying
log information will see multiple entries and take this into account log information will see multiple entries and take this into account
for their analytics purposes. for their analytics purposes.
7. Acknowledgements 8.1. Freshness in Voucher Requests
A concern has been raised that the voucher request produced by the
Pledge should contain some content (a nonce) from the Registrar and/
or MASA in order for those actors to verify that the voucher request
is fresh.
There are a number of operational problems with getting a nonce from
the MASA to the pledge. It is somewhat easier to collect a random
value from the Registrar, but as the Registrar is not yet vouched
for, such a Registrar nonce has little value. There are privacy and
logistical challenges to addressing these operational issues, so if
such a thing were to be considered, it would have to provide some
clear value. This section examines the impacts of not having a fresh
voucher request from the pledge.
Because the Registrar authenticates the Pledge a full Man-in-the-
Middle attack is not possible, despite the provisional TLS
authentication by the Pledge (see Section 5). Instead we examine the
case of a fake Registrar (Rm) that communicates with the Pledge in
parallel or in close time proximity with the intended Registrar.
(This scenario is intentionally supported as described in
Section 4.1).
The fake Registrar (Rm) can obtain a voucher signed by the MASA
either directly or through arbitrary intermediaries. Assuming that
the MASA accepts the voucher request (either because Rm is
collaborating with a legitimate Registrar according to supply chain
information, or because the MASA is in audit-log only mode), then a
voucher linking the pledge to the Registrar Rm is issued.
Such a voucher, when passed back to the Pledge, would link the pledge
to Registrar Rm, and would permit the Pledge to end the provisional
state. It now trusts Rm and, if it has any security vulnerabilities
leveragable by an Rm with full administrative control, can be assumed
to be a threat against the intended Registrar.
This flow is mitigated by the intended Registar verifying the audit
logs available from the MASA as described in Section 5.7. Rm might
chose to wait until after the intended Registrar completes the
authorization process before submitting the now-stale voucher
request. The Rm would need to remove the Pledge's nonce.
In order to successfully use the resulting "stale voucher" Rm would
have to attack the Pledge and return it to a bootstrapping enabled
state. This would require wiping the Pledge of current configuration
and triggering a re-bootstrapping of the Pledge. This is no more
likely than simply taking control of the Pledge directly but if this
is a consideration the target network is RECOMMENDED to take the
following steps:
o Ongoing network monitoring for unexpected bootstrapping attempts
by Pledges.
o Retreival and examination of MASA log information upon the
occurance of any such unexpected events. Rm will be listed in the
logs.
9. Acknowledgements
We would like to thank the various reviewers for their input, in We would like to thank the various reviewers for their input, in
particular Brian Carpenter, Toerless Eckert, Fuyu Eleven, Eliot Lear, particular Brian Carpenter, Toerless Eckert, Fuyu Eleven, Eliot Lear,
Sergey Kasatkin, Markus Stenberg, and Peter van der Stok Sergey Kasatkin, Markus Stenberg, and Peter van der Stok
8. References 10. References
8.1. Normative References 10.1. Normative References
[I-D.ietf-anima-autonomic-control-plane] [I-D.ietf-anima-autonomic-control-plane]
Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic
Control Plane", draft-ietf-anima-autonomic-control- Control Plane (ACP)", draft-ietf-anima-autonomic-control-
plane-06 (work in progress), March 2017. plane-10 (work in progress), September 2017.
[I-D.ietf-anima-voucher] [I-D.ietf-anima-voucher]
Watsen, K., Richardson, M., Pritikin, M., and T. Eckert, Watsen, K., Richardson, M., Pritikin, M., and T. Eckert,
"Voucher Profile for Bootstrapping Protocols", draft-ietf- "Voucher Profile for Bootstrapping Protocols", draft-ietf-
anima-voucher-04 (work in progress), July 2017. anima-voucher-05 (work in progress), August 2017.
[I-D.vanderstok-ace-coap-est] [I-D.vanderstok-ace-coap-est]
Kumar, S., Stok, P., Kampanakis, P., Furuhed, M., and S. Kumar, S., Stok, P., Kampanakis, P., Furuhed, M., and S.
Raza, "EST over secure CoAP (EST-coaps)", draft- Raza, "EST over secure CoAP (EST-coaps)", draft-
vanderstok-ace-coap-est-02 (work in progress), June 2017. vanderstok-ace-coap-est-02 (work in progress), June 2017.
[IDevID] IEEE Standard, "IEEE 802.1AR Secure Device Identifier", [IDevID] IEEE Standard, "IEEE 802.1AR Secure Device Identifier",
December 2009, <http://standards.ieee.org/findstds/ December 2009, <http://standards.ieee.org/findstds/
standard/802.1AR-2009.html>. standard/802.1AR-2009.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei, [RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei,
"Advanced Sockets Application Program Interface (API) for "Advanced Sockets Application Program Interface (API) for
IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003, IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003,
<http://www.rfc-editor.org/info/rfc3542>. <https://www.rfc-editor.org/info/rfc3542>.
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, Ed., "Extensible Authentication Protocol Levkowetz, Ed., "Extensible Authentication Protocol
(EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004, (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004,
<http://www.rfc-editor.org/info/rfc3748>. <https://www.rfc-editor.org/info/rfc3748>.
[RFC3927] Cheshire, S., Aboba, B., and E. Guttman, "Dynamic [RFC3927] Cheshire, S., Aboba, B., and E. Guttman, "Dynamic
Configuration of IPv4 Link-Local Addresses", RFC 3927, Configuration of IPv4 Link-Local Addresses", RFC 3927,
DOI 10.17487/RFC3927, May 2005, DOI 10.17487/RFC3927, May 2005,
<http://www.rfc-editor.org/info/rfc3927>. <https://www.rfc-editor.org/info/rfc3927>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007, DOI 10.17487/RFC4862, September 2007,
<http://www.rfc-editor.org/info/rfc4862>. <https://www.rfc-editor.org/info/rfc4862>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<https://www.rfc-editor.org/info/rfc4941>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, (TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008, DOI 10.17487/RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>. <https://www.rfc-editor.org/info/rfc5246>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>. <https://www.rfc-editor.org/info/rfc5280>.
[RFC5386] Williams, N. and M. Richardson, "Better-Than-Nothing [RFC5386] Williams, N. and M. Richardson, "Better-Than-Nothing
Security: An Unauthenticated Mode of IPsec", RFC 5386, Security: An Unauthenticated Mode of IPsec", RFC 5386,
DOI 10.17487/RFC5386, November 2008, DOI 10.17487/RFC5386, November 2008,
<http://www.rfc-editor.org/info/rfc5386>. <https://www.rfc-editor.org/info/rfc5386>.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, DOI 10.17487/RFC5652, September 2009, RFC 5652, DOI 10.17487/RFC5652, September 2009,
<http://www.rfc-editor.org/info/rfc5652>. <https://www.rfc-editor.org/info/rfc5652>.
[RFC5660] Williams, N., "IPsec Channels: Connection Latching", [RFC5660] Williams, N., "IPsec Channels: Connection Latching",
RFC 5660, DOI 10.17487/RFC5660, October 2009, RFC 5660, DOI 10.17487/RFC5660, October 2009,
<http://www.rfc-editor.org/info/rfc5660>. <https://www.rfc-editor.org/info/rfc5660>.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
DOI 10.17487/RFC6762, February 2013, DOI 10.17487/RFC6762, February 2013,
<http://www.rfc-editor.org/info/rfc6762>. <https://www.rfc-editor.org/info/rfc6762>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<http://www.rfc-editor.org/info/rfc6763>. <https://www.rfc-editor.org/info/rfc6763>.
[RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed., [RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
"Enrollment over Secure Transport", RFC 7030, "Enrollment over Secure Transport", RFC 7030,
DOI 10.17487/RFC7030, October 2013, DOI 10.17487/RFC7030, October 2013,
<http://www.rfc-editor.org/info/rfc7030>. <https://www.rfc-editor.org/info/rfc7030>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <https://www.rfc-editor.org/info/rfc7159>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228, Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014, DOI 10.17487/RFC7228, May 2014,
<http://www.rfc-editor.org/info/rfc7228>. <https://www.rfc-editor.org/info/rfc7228>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",
RFC 7951, DOI 10.17487/RFC7951, August 2016, RFC 7951, DOI 10.17487/RFC7951, August 2016,
<http://www.rfc-editor.org/info/rfc7951>. <https://www.rfc-editor.org/info/rfc7951>.
8.2. Informative References 10.2. Informative References
[I-D.behringer-homenet-trust-bootstrap] [I-D.behringer-homenet-trust-bootstrap]
Behringer, M., Pritikin, M., and S. Bjarnason, Behringer, M., Pritikin, M., and S. Bjarnason,
"Bootstrapping Trust on a Homenet", draft-behringer- "Bootstrapping Trust on a Homenet", draft-behringer-
homenet-trust-bootstrap-02 (work in progress), February homenet-trust-bootstrap-02 (work in progress), February
2014. 2014.
[I-D.ietf-anima-grasp] [I-D.ietf-anima-grasp]
Bormann, C., Carpenter, B., and B. Liu, "A Generic Bormann, C., Carpenter, B., and B. Liu, "A Generic
Autonomic Signaling Protocol (GRASP)", draft-ietf-anima- Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
grasp-13 (work in progress), June 2017. grasp-15 (work in progress), July 2017.
[I-D.ietf-netconf-zerotouch] [I-D.ietf-netconf-zerotouch]
Watsen, K., Abrahamsson, M., and I. Farrer, "Zero Touch Watsen, K., Abrahamsson, M., and I. Farrer, "Zero Touch
Provisioning for NETCONF or RESTCONF based Management", Provisioning for NETCONF or RESTCONF based Management",
draft-ietf-netconf-zerotouch-14 (work in progress), June draft-ietf-netconf-zerotouch-17 (work in progress),
2017. September 2017.
[I-D.lear-mud-framework] [I-D.ietf-opsawg-mud]
Lear, E., "Manufacturer Usage Description Framework", Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
draft-lear-mud-framework-00 (work in progress), January Description Specification", draft-ietf-opsawg-mud-12 (work
2016. in progress), October 2017.
[I-D.richardson-anima-state-for-joinrouter] [I-D.richardson-anima-state-for-joinrouter]
Richardson, M., "Considerations for stateful vs stateless Richardson, M., "Considerations for stateful vs stateless
join router in ANIMA bootstrap", draft-richardson-anima- join router in ANIMA bootstrap", draft-richardson-anima-
state-for-joinrouter-01 (work in progress), July 2016. state-for-joinrouter-01 (work in progress), July 2016.
[imprinting] [imprinting]
Wikipedia, "Wikipedia article: Imprinting", July 2015, Wikipedia, "Wikipedia article: Imprinting", July 2015,
<https://en.wikipedia.org/wiki/Imprinting_(psychology)>. <https://en.wikipedia.org/wiki/Imprinting_(psychology)>.
[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
December 1998, <http://www.rfc-editor.org/info/rfc2473>. December 1998, <https://www.rfc-editor.org/info/rfc2473>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque [RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217, Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014, DOI 10.17487/RFC7217, April 2014,
<http://www.rfc-editor.org/info/rfc7217>. <https://www.rfc-editor.org/info/rfc7217>.
[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection [RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection
Most of the Time", RFC 7435, DOI 10.17487/RFC7435, Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
December 2014, <http://www.rfc-editor.org/info/rfc7435>. December 2014, <https://www.rfc-editor.org/info/rfc7435>.
[RFC7575] Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A., [RFC7575] Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
Networking: Definitions and Design Goals", RFC 7575, Networking: Definitions and Design Goals", RFC 7575,
DOI 10.17487/RFC7575, June 2015, DOI 10.17487/RFC7575, June 2015,
<http://www.rfc-editor.org/info/rfc7575>. <https://www.rfc-editor.org/info/rfc7575>.
[Stajano99theresurrecting] [Stajano99theresurrecting]
Stajano, F. and R. Anderson, "The resurrecting duckling: Stajano, F. and R. Anderson, "The resurrecting duckling:
security issues for ad-hoc wireless networks", 1999, security issues for ad-hoc wireless networks", 1999,
<https://www.cl.cam.ac.uk/~fms27/papers/1999-StajanoAnd- <https://www.cl.cam.ac.uk/~fms27/
duckling.pdf>. papers/1999-StajanoAnd-duckling.pdf>.
Appendix A. IPv4 operations Appendix A. IPv4 operations
A.1. IPv4 Link Local addresses A.1. IPv4 Link Local addresses
Instead of an IPv6 link-local address, an IPv4 address may be Instead of an IPv6 link-local address, an IPv4 address may be
generated using [RFC3927] Dynamic Configuration of IPv4 Link-Local generated using [RFC3927] Dynamic Configuration of IPv4 Link-Local
Addresses. Addresses.
In the case that an IPv4 Local-Local address is formed, then the In the case that an IPv4 Local-Local address is formed, then the
skipping to change at page 41, line 48 skipping to change at page 56, line 28
A Registrar serving a large number of interfaces may not wish to A Registrar serving a large number of interfaces may not wish to
allocate resources to every interface at all times, but can instead allocate resources to every interface at all times, but can instead
dynamically allocate interfaces. It can do this by monitoring IPIP dynamically allocate interfaces. It can do this by monitoring IPIP
traffic that arrives on it's ACP interface, and when packets arrive traffic that arrives on it's ACP interface, and when packets arrive
from new Join Proxys, it can dynamically configure virtual from new Join Proxys, it can dynamically configure virtual
interfaces. interfaces.
A more sophisticated Registrar willing to modify the behaviour of A more sophisticated Registrar willing to modify the behaviour of
it's TCP and UDP stack could note the IPIP traffic origination in the it's TCP and UDP stack could note the IPIP traffic origination in the
socket control block and make information available to the TCP layer socket control block and make information available to the TCP layer
(for HTTPS connections), or to the the application (for CoAP (for HTTPS connections), or to the application (for CoAP connections)
connections) via a proprietary extension to the socket API. via a proprietary extension to the socket API.
C.3. Proxy Neighbor Discovery by Join Proxy C.3. Proxy Neighbor Discovery by Join Proxy
The Join Proxy MUST answer neighbor discovery messages for the The Join Proxy MUST answer neighbor discovery messages for the
address given by the Registrar as being it's link-local address. The address given by the Registrar as being it's link-local address. The
Join Proxy must also advertise this address as the address to which Join Proxy must also advertise this address as the address to which
to connect to when advertising it's existence. to connect to when advertising it's existence.
This proxy neighbor discovery means that the pledge will create TCP This proxy neighbor discovery means that the pledge will create TCP
and UDP connections to the correct Registrar address. This matters and UDP connections to the correct Registrar address. This matters
skipping to change at page 43, line 9 skipping to change at page 57, line 32
just pay attention to this extra information and add an appropriate just pay attention to this extra information and add an appropriate
IPIP header on outgoing. A CoAP over UDP mechanism may need to IPIP header on outgoing. A CoAP over UDP mechanism may need to
expose this extra information to the application as the UDP sockets expose this extra information to the application as the UDP sockets
are often not connected, and the application will need to specify the are often not connected, and the application will need to specify the
outgoing path on each packet send. outgoing path on each packet send.
Such an additional socket mechanism has not been standardized. Such an additional socket mechanism has not been standardized.
Terminating L2TP connections over IPsec transport mode suffers from Terminating L2TP connections over IPsec transport mode suffers from
the same challenges. the same challenges.
Appendix D. To be deprecated: Consolidation remnants Appendix D. MUD Extension
[[EDNOTE: As per working group feedback there were multiple instances
where this document repeated itself. To address this we have moved
all text to this appendix and restored only one copy of each
normative discussion. The next pass will reduce and delete this
appendix to '0'; although some may be maintained in a design
considerations appendix.]]
D.1. Functional Overview
Entities behave in an autonomic fashion. They discover each other
and autonomically bootstrap into a key infrastructure delineating the
autonomic domain. See [RFC7575] for more information.
This section details the state machine and operational flow for each
of the main three entities. The pledge, the domain (primarily a
Registrar) and the MASA service.
A representative flow is shown in Figure 2:
+--------+ +---------+ +------------+ +------------+
| Pledge | | Circuit | | Domain | | Vendor |
| | | Proxy | | Registrar | | Service |
| | | | | | | (Internet |
+--------+ +---------+ +------------+ +------------+
| | | |
|<-RFC3927 IPv4 adr | Appendix A | |
or|<-RFC4862 IPv6 adr | | |
| | | |
|-------------------->| | |
| optional: mDNS query| Appendix B | |
| RFC6763/RFC6762 | | |
| | | |
|<--------------------| | |
| GRASP M_FLOOD | | |
| periodic broadcast| | |
| | | |
|<------------------->C<----------------->| |
| TLS via the Circuit Proxy | |
|<--Registrar TLS server authentication---| |
[PROVISIONAL accept of server cert] | |
P---X.509 client authentication---------->| |
P | | |
P---Request Voucher (include nonce)------>| |
P | | |
P | /---> | |
P | | [accept device?] |
P | | [contact Vendor] |
P | | |--Pledge ID-------->|
P | | |--Domain ID-------->|
P | | |--optional:nonce--->|
P | | | [extract DomainID]
P | | | |
P | optional: | [update audit log]
P | |can | |
P | |occur | |
P | |in | |
P | |advance | |
P | | | |
P | | |<-device audit log--|
P | | |<- voucher ---------|
P | \----> | |
P | | |
P | [verify audit log and voucher] |
P | | |
P<------voucher---------------------------| |
[verify voucher ] | | |
[verify provisional cert| | |
| | | |
|<--------------------------------------->| |
| Continue with RFC7030 enrollment | |
| using now bidirectionally authenticated | |
| TLS session. | | |
| | | |
| | | |
| | | |
Figure 2
[[UNRESOLVED:need to restore some functional overview section for all
these diagrams]]In order to obtain a Voucher and associated logs a
Registrar contacts the MASA service Service using REST calls:
+-----------+ +----------+ +-----------+ +----------+
| New | | Circuit | | | | |
| Entity | | Proxy | | Registrar | | Vendor |
| | | | | | | |
++----------+ +--+-------+ +-----+-----+ +--------+-+
| | | |
| | | |
| TLS hello | TLS hello | |
Establish +---------------C---------------> |
TLS | | | |
connection | | Server Cert | |
<---------------C---------------+ |
| Client Cert | | |
+---------------C---------------> |
| | | |
HTTP REST | POST /requestvoucher | |
Data +--------------------nonce------> |
| . | /requestvoucher|
| . +---------------->
| <----------------+
| | /requestlog |
| +---------------->
| voucher <----------------+
<-------------------------------+ |
| (optional config information) | |
| . | |
| . | |
Figure 8
In some use cases the Registrar may need to contact the Vendor in
advanced, for example when the target network is air-gapped. The
nonceless request format is provided for this and the resulting flow
is slightly different. The security differences associated with not
knowing the nonce are discussed below:
+-----------+ +----------+ +-----------+ +----------+
| New | | Circuit | | | | |
| Entity | | Proxy | | Registrar | | Vendor |
| | | | | | | |
++----------+ +--+-------+ +-----+-----+ +--------+-+
| | | |
| | | |
| | | /requestvoucher|
| | (nonce +---------------->
| | unknown) <----------------+
| | | /requestlog |
| | +---------------->
| | <----------------+
| TLS hello | TLS hello | |
Establish +---------------C---------------> |
TLS | | | |
connection | | Server Cert | |
<---------------C---------------+ |
| Client Cert | | |
| | | |
HTTP REST | POST /requestvoucher | |
Data +----------------------nonce----> (discard |
| voucher | nonce) |
<-------------------------------+ |
| (optional config information) | |
| . | |
| . | |
Figure 9
D.1.1. Behavior of a Pledge
A pledge that has not yet been bootstrapped attempts to find a local
domain and join it. A pledge [[RESOLVED:MUST NOT]] automatically
initiate bootstrapping if it has already been configured or is in the
process of being configured.
States of a pledge are as follows:
+--------------+
| Factory |
| default |
+------+-------+
|
+------v-------+
| Discover |
+------------> |
| +------+-------+
| |
| +------v-------+
| | Identity |
^------------+ |
| rejected +------+-------+
| |
| +------v-------+
| | Request |
| | Join |
| +------+-------+
| |
| +------v-------+
| | Imprint | Optional
^------------+ <--+Manual input (Appendix C)
| Bad Vendor +------+-------+
| response |
| +------v-------+
| | Enroll |
^------------+ |
| Enroll +------+-------+
| Failure |
| +------v-------+
| | Enrolled |
^------------+ |
Factory +--------------+
reset
Figure 3
State descriptions for the pledge are as follows:
1. Discover a communication channel to a Registrar.
2. Identify itself. This is done by presenting an X.509 IDevID
credential to the discovered Registrar (via the Proxy) in a TLS
handshake. (The Registrar credentials are only provisionally
accepted at this time).
3. Requests to Join the discovered Registrar. A unique nonce
[[RESOLVED:can be]] included ensuring that any responses can be
associated with this particular bootstrapping attempt.
4. Imprint on the Registrar. This requires verification of the
vendor service provided voucher. A voucher contains sufficient
information for the Pledge to complete authentication of a
Registrar. (It enables the Pledge to finish authentication of
the Registrar TLS server certificate).
5. Enroll. By accepting the domain specific information from a
Registrar, and by obtaining a domain certificate from a Registrar
using a standard enrollment protocol, e.g. Enrollment over
Secure Transport (EST) [RFC7030].
6. The Pledge is now a member of, and can be managed by, the domain
and will only repeat the discovery aspects of bootstrapping if it
is returned to factory default settings.
The following sections describe each of these steps in more detail.
D.1.1.1. Discovery
[[RESOLVED:TEXT moved up into above]]
D.1.1.2. Identity
The Pledge identifies itself during the communication protocol
handshake. If the client identity is rejected (that is, the TLS
handshake does not complete) the Pledge repeats the Identity process
using the next proxy or discovery method available.
[[RESOLVED: need normative statement in protocol section]] The
bootstrapping protocol server is not initially authenticated. Thus
the connection is provisional and all data received is untrusted
until sufficiently validated even though it is over a TLS connection.
This is aligned with the existing provisional mode of EST [RFC7030]
during s4.1.1 "Bootstrap Distribution of CA Certificates". See
Section 3.4 for more information about when the TLS connection
authentication is completed.
[[RESOLVED:]]All security associations established are between the
new device and the Bootstrapping server regardless of proxy
operations.
D.1.1.2.1. Concurrent attempts to join
[[RESOLVED: by dropping this text. the "priority mechanism" is
unspecified thus any discussion is unclear. Not only that once an
initial request is sent to the registrar the question of multiple
MASA interactions has already occurred. Nothing breaks if
implementations do this. I've added text to the security
considerations indicating the end result (MASA entries that might be
ignored by the device but which confuse the end administrator)]] The
Pledge MAY attempt multiple mechanisms concurrently, but if it does
so, it MUST wait in the provisional state until all mechanisms have
either succeeded or failed, and then MUST proceed with the highest
priority mechanism which has succeed. To proceed beyond this point,
specifically, to provide a nonce, could result in the MASA
gratuitously auditing a connection.
D.1.1.3. Request Join
The Pledge POSTs a request to join the domain to the Bootstrapping
server. This request contains a Pledge generated nonce and informs
the Bootstrapping server which imprint methods the Pledge will
accept.
The nonce ensures the Pledge can verify that responses are specific
to this bootstrapping attempt. This minimizes the use of global time
and provides a substantial benefit for devices without a valid clock.
D.1.1.3.1. Redirects during the Join Process
[[RESOVED via current root protocol discussion. reference to
mdnsmethods is dropped]] EST [RFC7030] describes situations where the
bootstrapping server MAY redirect the client to an alternate server
via a 3xx status code. Such redirects MAY be accepted if the pledge
has used the methods described in Appendix B, in combination with an
implicit trust anchor. Redirects during the provisional period are
otherwise unstrusted, and MUST cause a failure.
D.1.1.4. Imprint
The Pledge validates the voucher and accepts the Registrar ID. The
provisional TLS connection is validated using the Registrar ID from
the voucher.
D.1.1.5. Lack of realtime clock APPENDIX
[[RESOVED: entire section promoted back into the main text]]
Many devices when bootstrapping do not have knowledge of the current
time. Mechanisms like Network Time Protocols can not be secured
until bootstrapping is complete. Therefore bootstrapping is defined
in a method that does not require knowledge of the current time.
Unfortunately there are moments during bootstrapping when
certificates are verified, such as during the TLS handshake, where
validity periods are confirmed. This paradoxical "catch-22" is
resolved by the Pledge maintaining a concept of the current "window"
of presumed time validity that is continually refined throughout the
bootstrapping process as follows:
o Initially the Pledge does not know the current time.
o During Pledge authentiation by the Registrar a realtime clock can
be used by the Registrar. This bullet expands on a closely
related issue regarding Pledge lifetimes. RFC5280 indicates that
long lived Pledge certifiates "SHOULD be assigned the
GeneralizedTime value of 99991231235959Z" [RFC7030] so the
Registrar MUST support such lifetimes and SHOULD support ignoring
Pledge lifetimes if they did not follow the RFC5280
recommendations.
o The Pledge authenticates the voucher presented to it. During this
authentication the Pledge ignores certificate lifetimes (by
necessity because it does not have a clock). The voucher itself
SHOULD contain the nonce included in the original request which
proves the voucher is fresh.
o Once the voucher is accepted the validity period of the
domainCAcert in the voucher (see Section 3.4) now serves as a
valid time window. Any subsequent certificate validity periods
checked during RFC5280 path validation MUST occur within this
window.
o When accepting an enrollment certificate the validity period
within the new certificate is assumed to be valid by the Pledge.
The Pledge is now willing to use this credential for client
authentication.
D.1.1.6. Enrollment
As the final step of bootstrapping a Registrar helps to issue a
domain specific credential to the Pledge. For simplicity in this
document, a Registrar primarily facilitates issuing a credential by
acting as an RFC5280 Registration Authority for the Domain
Certification Authority.
Enrollment proceeds as described in [RFC7030]. Authentication of the
EST server is done using the Voucher rather than the methods defined
in EST.
[[RESOLVED: moved to protocol discussion]]Once the Voucher is
received, as specified in this document, the client has sufficient
information to leverage the existing communication channel with a
Registrar to continue an EST RFC7030 enrollment. Enrollment picks up
at RFC7030 section 4.1.1. bootstrapping where the Voucher provides
the "out-of-band" CA certificate fingerprint (in this case the full
CA certificate) such that the client can now complete the TLS server
authentication. At this point the client continues with EST
enrollment operations including "CA Certificates Request", "CSR
Attributes" and "Client Certificate Request" or "Server-Side Key
Generation".
[[RESOLVED: included into EST discussion]]For the purposes of
creating the ANIMA Autonomic Control Plane, the contents of the new
certificate MUST be carefully specified.
[I-D.ietf-anima-autonomic-control-plane] section 5.1.1 contains
details. The Registrar MUST provide the the correct ACP information
to populate the subjectAltName / rfc822Name field in the "CSR
Attributes" step.
D.1.1.7. Being Managed
[[RESOLVED: by slight change to introduction text.]] Functionality to
provide generic "configuration" information is supported. The
parsing of this data and any subsequent use of the data, for example
communications with a Network Management System is out of scope but
is expected to occur after bootstrapping enrollment is complete.
This ensures that all communications with management systems which
can divulge local security information (e.g. network topology or raw
key material) is secured using the local credentials issued during
enrollment.
The Pledge uses bootstrapping to join only one domain. Management by
multiple domains is out-of-scope of bootstrapping. After the device
has successfully joined a domain and is being managed it is plausible
that the domain can insert credentials for other domains depending on
the device capabilities.
See Appendix D.1.5.
D.1.2. Behavior of a Join Proxy
The role of the Proxy is to facilitate communications. The Proxy
forwards packets between the Pledge and a Registrar that has been
configured on the Proxy.
[[UNRESOLVED: since proxy behavior is not visible we can limit
ourselves to discussion of what the protocol does to enable/faciliate
a theoretical proxy]]The Proxy does not terminate the TLS handshake.
[[UNRESOLVED: this is an anima architecture requirement to use BRSKI?
move to there?]] A Proxy is always assumed even if it is directly
integrated into a Registrar. (In a completely autonomic network, the
Registrar MUST provide proxy functionality so that it can be
discovered, and the network can grow concentrically around the
Registrar)
As a result of the Proxy Discovery process in section
Appendix D.1.1.1, the port number exposed by the proxy does not need
to be well known, or require an IANA allocation.
If the Proxy joins an Autonomic Control Plane
([I-D.ietf-anima-autonomic-control-plane]) it SHOULD use Autonomic
Control Plane secured GRASP ([I-D.ietf-anima-grasp]) to discovery the
Registrar address and port. As part of the discovery process, the
proxy mechanism (Circuit Proxy vs IPIP encapsulation) is agreed to
between the Registrar and Join Proxy.
For the IPIP encapsulation methods, the port announced by the Proxy
MUST be the same as on the registrar in order for the proxy to remain
stateless.
In order to permit the proxy functionality to be implemented on the
maximum variety of devices the chosen mechanism SHOULD use the
minimum amount of state on the proxy device. While many devices in
the ANIMA target space will be rather large routers, the proxy
function is likely to be implemented in the control plane CPU of such
a device, with available capabilities for the proxy function similar
to many class 2 IoT devices.
The document [I-D.richardson-anima-state-for-joinrouter] provides a
more extensive analysis of the alternative proxy methods.
D.1.2.1. CoAP connection to Registrar
[[RESOLVED:this section thus removed]]The CoAP mechanism was
depreciated.
D.1.2.2. HTTPS proxy connection to Registrar
The proxy SHOULD also provide one of: an IPIP encapsulation of HTTP
traffic on TCP port TBD to the registrar, or a TCP circuit proxy that
connects the Pledge to a Registrar.
When the Proxy provides a circuit proxy to a Registrar the Registrar
MUST accept HTTPS connections.
When the Proxy provides a stateless IPIP encapsulation to a
Registrar, then the Registrar will have to perform IPIP
decapsulation, remembering the originating outer IPIP source address
in order to qualify the inner link-local address. This is a kind of
encapsulation and processing which is similar in many ways to how
mobile IP works.
Being able to connect a TCP (HTTP) or UDP (CoAP) socket to a link-
local address with an encapsulated IPIP header requires API
extensions beyond [RFC3542] for UDP use, and requires a form of
connection latching (see section 4.1 of [RFC5386] and all of
[RFC5660], except that a simple IPIP tunnel is used rather than an
IPsec tunnel).
D.1.3. Behavior of the Registrar
A Registrar listens for Pledges and determines if they can join the
domain. A Registrar obtains a Voucher from the MASA service and
delivers them to the Pledge as well as facilitating enrollment with
the domain PKI.
[[RESOLVED: moved to discovery discussion]] A Registrar is typically
configured manually. When the Registrar joins an Autonomic Control
Plane ([I-D.ietf-anima-autonomic-control-plane]) it MUST respond to
GRASP ([I-D.ietf-anima-grasp]) M_DISCOVERY message. See
Section 3.1.2
Registrar behavior is as follows:
Contacted by Pledge
+
|
+-------v----------+
| Entity | fail?
| Authentication +---------+
+-------+----------+ |
| |
+-------v----------+ |
| Entity | fail? |
| Authorization +--------->
+-------+----------+ |
| |
+-------v----------+ |
| Claiming the | fail? |
| Entity +--------->
+-------+----------+ |
| |
+-------v----------+ |
| Log Verification | fail? |
| +--------->
+-------+----------+ |
| |
+-------v----------+ +----v-------+
| Forward | | |
| Voucher | | Reject |
| to the Pledge | | Device |
| | | |
+------------------+ +------------+
Figure 4
D.1.3.1. Pledge Authentication
The applicable authentication methods detailed in EST [RFC7030] are:
o [[RESOLVED:pointed out in protocol details]]the use of an X.509
IDevID credential during the TLS client authentication,
o or the use of a secret that is transmitted out of band between the
Pledge and a Registrar (this use case is not autonomic).
In order to validate the X.509 IDevID credential a Registrar
maintains a database of vendor trust anchors (e.g. vendor root
certificates or keyIdentifiers for vendor root public keys). For
user interface purposes this database can be mapped to colloquial
vendor names. Registrars can be shipped with the trust anchors of a
significant number of third-party vendors within the target market.
D.1.3.2. Pledge Authorization
[[UNRESOLVED: this is referenced above as how the MASA does
authorization. That is incorrect]]
In a fully automated network all devices must be securely identified
and authorized to join the domain.
A Registrar accepts or declines a request to join the domain, based
on the authenticated identity presented. Automated acceptance
criteria include:
o allow any device of a specific type (as determined by the X.509
IDevID),
o allow any device from a specific vendor (as determined by the
X.509 IDevID),
o allow a specific device from a vendor (as determined by the X.509
IDevID) against a domain white list. (The mechanism for checking
a shared white list potentially used by multiple Registrars is out
of scope).
[[RESOLVED: this looks like good text to include in above]]To look
the Pledge up in a domain white list a consistent method for
extracting device identity from the X.509 certificate is required.
RFC6125 describes Domain-Based Application Service identity but here
we require Vendor Device-Based identity. The subject field's DN
encoding MUST include the "serialNumber" attribute with the device's
unique serial number. In the language of RFC6125 this provides for a
SERIALNUM-ID category of identifier that can be included in a
certificate and therefore that can also be used for matching
purposes. The SERIALNUM-ID whitelist is collated according to vendor
trust anchor since serial numbers are not globally unique.
[[RESOLVED: into log request]]The Registrar MUST use the vendor
provided MASA service to verify that the device's history log does
not include unexpected Registrars. If a device had previously
registered with another domain, a Registrar of that domain would show
in the log.
[[RESOLVED: est integration section used 'SHOULD']]The authorization
performed during BRSKI MAY be used for EST enrollment requests by
proceeding with EST enrollment using the authenticated and authorized
TLS connection. This minimizes the number of cryptographic and
protocol operations necessary to complete bootstrapping of the local
key infrastructure.
D.1.3.3. Claiming the Pledge
Claiming an pledge establishes an audit log at the MASA server and
provides a Registrar with proof, in the form of the Voucher, that the
log entry has been inserted. As indicated in Appendix D.1.1.4 a
Pledge will only proceed with bootstrapping if a Voucher has been
received. The Pledge therefore enforces that bootstrapping only
occurs if the claim has been logged. There is no requirement for the
vendor to definitively know that the device is owned by the
Registrar.
The Registrar obtains the MASA URI via static configuration or by
extracting it from the X.509 IDevID credential. See Section 2.2.
During initial bootstrapping the Pledge provides a nonce specific to
the particular bootstrapping attempt. [[RESOLVED: to resolve this I
updated many points where vouchers are referenced]]The Registrar
SHOULD include this nonce when claiming the Pledge from the MASA
service. Claims from an unauthenticated Registrar are only serviced
by the MASA resource if a nonce is provided.
The Registrar can claim a Pledge that is offline by forming the
request using the entities unique identifier and not including a
nonce in the claim request. Vouchers obtained in this way do not
have a lifetime and they provide a permanent method for the domain to
claim the device. Evidence of such a claim is provided in the audit
log entries available to any future Registrar. Such claims reduce
the ability for future domains to secure bootstrapping and therefore
the Registrar MUST be authenticated by the MASA service although no
requirement is implied that the MASA associates this authentication
with ownership.
An Ownership Voucher requires the vendor to definitively know that a
device is owned by a specific domain. The method used to "claim"
this are out-of-scope. A MASA ignores or reports failures when an
attempt is made to claim a device that has a an Ownership Voucher.
D.1.3.4. Log Verification
A Registrar requests the log information for the Pledge from the MASA
service. The log is verified to confirm that the following is true
to the satisfaction of a Registrar's configured policy:
o Any nonceless entries in the log are associated with domainIDs
recognized by the registrar.
o Any nonce'd entries are older than when the domain is known to
have physical possession of the Pledge or that the domainIDs are
recognized by the registrar.
If any of these criteria are unacceptable to a Registrar the entity
is rejected. [[RESOLVED: moved to main body]] A Registrar MAY be
configured to ignore the history of the device but it is RECOMMENDED
that this only be configured if hardware assisted NEA [RFC5209] is
supported.
[[RESOLVED: added to main text]]This document specifies a simple log
format as provided by the MASA service to the registar. This format
could be improved by distributed consensus technologies that
integrate vouchers with a technologies such as block-chain or hash
trees or the like. Doing so is out of the scope of this document but
are anticipated improvements for future work.
D.1.4. Behavior of the MASA Service
[[UNRESOLVED: primary value of keeping this discussion is to
distinguish between registrar and masa particularly wrt to the
protocol functions provided. perhaps add statements in each protocol
entry "provided by masa" etc?]]
The Manufacturer Authorized Signing Authority service is directly
provided by the manufacturer, or can be provided by a third party the
manufacturer authorizes. It is a cloud resource. The MASA service
provides the following functionalities to Registrars:
Issue Vouchers: In response to Registrar requests the MASA service
issues vouchers. Depending on the MASA policy the Registrar claim
of device ownership is either accepted or verified using out-of-
scope methods (that are expected to improve over time).
Log Vouchers Issued: When a voucher is issued the act of issuing it
includes updating the certifiable logs. Future work to enhance
and distribute these logs is out-of-scope but expected over time.
Provide Logs: As a baseline implementation of the certified logging
mechanism the MASA is repsonsible for reporting logged
information. The current method involves trusting the MASA.
Other logging methods where the MASA is less trusted are expected
to be developed over time.
D.1.5. Leveraging the new key infrastructure / next steps
As the devices have a common trust anchor, device identity can be
securely established, making it possible to automatically deploy
services across the domain in a secure manner.
Examples of services:
o Device management.
o Routing authentication.
o Service discovery.
D.1.5.1. Network boundaries
When a device has joined the domain, it can validate the domain
membership of other devices. This makes it possible to create trust
boundaries where domain members have higher level of trusted than
external devices. Using the autonomic User Interface, specific
devices can be grouped into to sub domains and specific trust levels
can be implemented between those.
D.1.6. Interactions with Network Access Control
[[RESOLVED: via paragraph in 'scope of solution' discussion.]]
The assumption is that Network Access Control (NAC) completes using
the Pledge 's X.509 IDevID credentials and results in the device
having sufficient connectivity to discovery and communicate with the
proxy. Any additional connectivity or quarantine behavior by the NAC
infrastructure is out-of-scope. After the devices has completed
bootstrapping the mechanism to trigger NAC to re-authenticate the
device and provide updated network privileges is also out-of-scope.
This achieves the goal of a bootstrap architecture that can integrate
with NAC but does not require NAC within the network where it wasn't
previously required. Future optimizations can be achieved by
integrating the bootstrapping protocol directly into an initial EAP
exchange.
D.2. Domain Operator Activities
This section describes how an operator interacts with a domain that
supports the bootstrapping as described in this document.
D.2.1. Instantiating the Domain Certification Authority
This is a one time step by the domain administrator. This is an "off
the shelf" CA with the exception that it is designed to work as an
integrated part of the security solution. This precludes the use of
3rd party certification authority services that do not provide
support for delegation of certificate issuance decisions to a domain
managed Registration Authority.
D.2.2. Instantiating the Registrar
This is a one time step by the domain administrator. One or more
devices in the domain are configured take on a Registrar function.
A device can be configured to act as a Registrar or a device can
auto-select itself to take on this function, using a detection
mechanism to resolve potential conflicts and setup communication with
the Domain Certification Authority. Automated Registrar selection is
outside scope for this document.
D.2.3. Accepting New Entities
For each Pledge the Registrar is informed of the unique identifier
(e.g. serial number) along with the manufacturer's identifying
information (e.g. manufacturer root certificate). This can happen in
different ways:
1. Default acceptance: In the simplest case, the new device asserts
its unique identity to a Registrar. The registrar accepts all
devices without authorization checks. This mode does not provide
security against intruders and is not recommended.
2. Per device acceptance: The new device asserts its unique identity
to a Registrar. A non-technical human validates the identity,
for example by comparing the identity displayed by the registrar
(for example using a smartphone app) with the identity shown on
the packaging of the device. Acceptance may be triggered by a
click on a smartphone app "accept this device", or by other forms
of pairing. See also [I-D.behringer-homenet-trust-bootstrap] for
how the approach could work in a homenet.
3. Whitelist acceptance: In larger networks, neither of the previous
approaches is acceptable. Default acceptance is not secure, and
a manual per device methods do not scale. Here, the registrar is
provided a priori with a list of identifiers of devices that
belong to the network. This list can be extracted from an
inventory database, or sales records. If a device is detected
that is not on the list of known devices, it can still be
manually accepted using the per device acceptance methods.
4. Automated Whitelist: an automated process that builds the The following extension augments the MUD model to include a single
necessary whitelists and inserts them into the larger network node, as described in [I-D.ietf-opsawg-mud] section 3.6, using the
domain infrastructure is plausible. Once set up, no human following sample module that has the following tree structure:
intervention is required in this process. Defining the exact
mechanisms for this is out of scope although the registrar
authorization checks is identified as the logical integration
point of any future work in this area.
None of these approaches require the network to have permanent module: ietf-mud-brski-masa
Internet connectivity. Even when the Internet based MASA service is augment /ietf-mud:mud:
used, it is possible to pre-fetch the required information from the +--rw masa-server? inet:uri
MASA a priori, for example at time of purchase such that devices can
enroll later. This supports use cases where the domain network may
be entirely isolated during device deployment.
Additional policy can be stored for future authorization decisions. The model is defined as follows:
For example an expected deployment time window or that a certain
Proxy must be used.
D.2.4. Automatic Enrollment of Devices <CODE BEGINS>
module ietf-mud-brski-masa {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-mud-brski-masa";
prefix ietf-mud-brski-masa;
import ietf-mud {
prefix ietf-mud;
}
import ietf-inet-types {
prefix inet;
}
The approach outlined in this document provides a secure zero-touch organization
method to enroll new devices without any pre-staged configuration. "IETF ANIMA (Autonomic Networking Integrated Model and
New devices communicate with already enrolled devices of the domain, Approach) Working Group";
which proxy between the new device and a Registrar. As a result of contact
this completely automatic operation, all devices obtain a domain "WG Web: http://tools.ietf.org/wg/anima/
based certificate. WG List: anima@ietf.org
";
description
"BRSKI extension to a MUD file to indicate the
MASA URL.";
D.2.5. Secure Network Operations revision 2017-10-09 {
description
"Initial revision.";
reference
"RFC XXXX: Manufacturer Usage Description
Specification";
}
The certificate installed in the previous step can be used for all augment "/ietf-mud:mud" {
subsequent operations. For example, to determine the boundaries of description
the domain: If a neighbor has a certificate from the same trust "BRSKI extension to a MUD file to indicate the
anchor it can be assumed "inside" the same organization; if not, as MASA URL.";
outside. See also Appendix D.1.5.1. The certificate can also be leaf masa-server {
used to securely establish a connection between devices and central type inet:uri;
control functions. Also autonomic transactions can use the domain description
certificates to authenticate and/or encrypt direct interactions "This value is the URI of the MASA server";
between devices. The usage of the domain certificates is outside }
scope for this document. }
}
<CODE ENDS>
Authors' Addresses Authors' Addresses
Max Pritikin Max Pritikin
Cisco Cisco
Email: pritikin@cisco.com Email: pritikin@cisco.com
Michael C. Richardson Michael C. Richardson
Sandelman Software Works Sandelman Software Works
Email: mcr+ietf@sandelman.ca Email: mcr+ietf@sandelman.ca
URI: http://www.sandelman.ca/ URI: http://www.sandelman.ca/
Michael H. Behringer Michael H. Behringer
Cisco Cisco
Email: mbehring@cisco.com Email: mbehring@cisco.com
Steinthor Bjarnason Steinthor Bjarnason
Cisco Arbor Networks
Email: sbjarnas@cisco.com Email: sbjarnason@arbor.net
Kent Watsen Kent Watsen
Juniper Networks Juniper Networks
Email: kwatsen@juniper.net Email: kwatsen@juniper.net
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