< draft-ietf-anima-constrained-join-proxy-09.txt   draft-ietf-anima-constrained-join-proxy-10.txt >
anima Working Group M. Richardson anima Working Group M. Richardson
Internet-Draft Sandelman Software Works Internet-Draft Sandelman Software Works
Intended status: Standards Track P. van der Stok Intended status: Standards Track P. van der Stok
Expires: 26 September 2022 vanderstok consultancy Expires: 16 October 2022 vanderstok consultancy
P. Kampanakis P. Kampanakis
Cisco Systems Cisco Systems
25 March 2022 14 April 2022
Constrained Join Proxy for Bootstrapping Protocols Constrained Join Proxy for Bootstrapping Protocols
draft-ietf-anima-constrained-join-proxy-09 draft-ietf-anima-constrained-join-proxy-10
Abstract Abstract
This document extends the work of Bootstrapping Remote Secure Key
Infrastructures (BRSKI) by replacing the Circuit-proxy between Pledge
and Registrar by a stateless/stateful constrained Join Proxy. The
constrained Join Proxy is a mesh neighbor of the Pledge and can relay
a DTLS session originating from a Pledge with only link-local
addresses to a Registrar which is not a mesh neighbor of the Pledge.
This document defines a protocol to securely assign a Pledge to a This document defines a protocol to securely assign a Pledge to a
domain, represented by a Registrar, using an intermediary node domain, represented by a Registrar, using an intermediary node
between Pledge and Registrar. This intermediary node is known as a between Pledge and Registrar. This intermediary node is known as a
"constrained Join Proxy". An enrolled Pledge can act as a "constrained Join Proxy". An enrolled Pledge can act as a
constrained Join Proxy. constrained Join Proxy.
This document extends the work of Bootstrapping Remote Secure Key
Infrastructures (BRSKI) by replacing the Circuit-proxy between Pledge
and Registrar by a stateless/stateful constrained Join Proxy. It
relays join traffic from the Pledge to the Registrar.
Status of This Memo Status of This Memo
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Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 3. Requirements Language . . . . . . . . . . . . . . . . . . . . 5
4. Join Proxy functionality . . . . . . . . . . . . . . . . . . 5 4. constrained Join Proxy functionality . . . . . . . . . . . . 5
5. Join Proxy specification . . . . . . . . . . . . . . . . . . 5 5. constrained Join Proxy specification . . . . . . . . . . . . 7
5.1. Stateful Join Proxy . . . . . . . . . . . . . . . . . . . 6 5.1. Stateful Join Proxy . . . . . . . . . . . . . . . . . . . 7
5.2. Stateless Join Proxy . . . . . . . . . . . . . . . . . . 7 5.2. Stateless Join Proxy . . . . . . . . . . . . . . . . . . 8
5.3. Stateless Message structure . . . . . . . . . . . . . . . 9 5.3. Stateless Message structure . . . . . . . . . . . . . . . 10
6. Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6. Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.1. Join Proxy discovers Registrar . . . . . . . . . . . . . 11 6.1. Join Proxy discovers Registrar . . . . . . . . . . . . . 12
6.1.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 12 6.1.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 13
6.1.2. GRASP discovery . . . . . . . . . . . . . . . . . . . 12 6.1.2. GRASP discovery . . . . . . . . . . . . . . . . . . . 13
6.1.3. 6tisch discovery . . . . . . . . . . . . . . . . . . 12 6.1.3. 6tisch discovery . . . . . . . . . . . . . . . . . . 13
6.2. Pledge discovers Registrar . . . . . . . . . . . . . . . 12 6.2. Pledge discovers Registrar . . . . . . . . . . . . . . . 13
6.2.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 12 6.2.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 13
6.2.2. GRASP discovery . . . . . . . . . . . . . . . . . . . 13 6.2.2. GRASP discovery . . . . . . . . . . . . . . . . . . . 14
6.2.3. 6tisch discovery . . . . . . . . . . . . . . . . . . 13 6.2.3. 6tisch discovery . . . . . . . . . . . . . . . . . . 14
6.3. Pledge discovers Join Proxy . . . . . . . . . . . . . . . 13 6.3. Pledge discovers Join Proxy . . . . . . . . . . . . . . . 14
6.3.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 13 6.3.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 14
6.3.2. GRASP discovery . . . . . . . . . . . . . . . . . . . 14 6.3.2. GRASP discovery . . . . . . . . . . . . . . . . . . . 15
6.3.3. 6tisch discovery . . . . . . . . . . . . . . . . . . 14 6.3.3. 6tisch discovery . . . . . . . . . . . . . . . . . . 15
7. Comparison of stateless and stateful modes . . . . . . . . . 14 7. Comparison of stateless and stateful modes . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 15 8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
9.1. Resource Type Attributes registry . . . . . . . . . . . . 15 9.1. Resource Type Attributes registry . . . . . . . . . . . . 17
9.2. service name and port number registry . . . . . . . . . . 15 9.2. service name and port number registry . . . . . . . . . . 17
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18
12. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 16 12. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 18
12.1. 06 to 07 . . . . . . . . . . . . . . . . . . . . . . . . 16 12.1. 10 to 09 . . . . . . . . . . . . . . . . . . . . . . . . 18
12.2. 05 to 06 . . . . . . . . . . . . . . . . . . . . . . . . 16 12.2. 09 to 07 . . . . . . . . . . . . . . . . . . . . . . . . 18
12.3. 04 to 05 . . . . . . . . . . . . . . . . . . . . . . . . 16 12.3. 06 to 07 . . . . . . . . . . . . . . . . . . . . . . . . 18
12.4. 03 to 04 . . . . . . . . . . . . . . . . . . . . . . . . 17 12.4. 05 to 06 . . . . . . . . . . . . . . . . . . . . . . . . 19
12.5. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 17 12.5. 04 to 05 . . . . . . . . . . . . . . . . . . . . . . . . 19
12.6. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 17 12.6. 03 to 04 . . . . . . . . . . . . . . . . . . . . . . . . 19
12.7. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 17 12.7. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 19
12.8. 00 to 00 . . . . . . . . . . . . . . . . . . . . . . . . 17 12.8. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 19
12.9. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 19
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 12.10. 00 to 00 . . . . . . . . . . . . . . . . . . . . . . . . 19
13.1. Normative References . . . . . . . . . . . . . . . . . . 17 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
13.2. Informative References . . . . . . . . . . . . . . . . . 18 13.1. Normative References . . . . . . . . . . . . . . . . . . 20
Appendix A. Stateless Proxy payload examples . . . . . . . . . . 20 13.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 Appendix A. Stateless Proxy payload examples . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
The Bootstrapping Remote Secure Key Infrastructure (BRSKI) protocol The Bootstrapping Remote Secure Key Infrastructure (BRSKI) protocol
described in [RFC8995] provides a solution for a secure zero-touch described in [RFC8995] provides a solution for a secure zero-touch
(automated) bootstrap of new (unconfigured) devices. In the context (automated) bootstrap of new (unconfigured) devices. In the context
of BRSKI, new devices, called "Pledges", are equipped with a factory- of BRSKI, new devices, called "Pledges", are equipped with a factory-
installed Initial Device Identifier (IDevID) (see [ieee802-1AR]), and installed Initial Device Identifier (IDevID) (see [ieee802-1AR]), and
are enrolled into a network. BRSKI makes use of Enrollment over are enrolled into a network. BRSKI makes use of Enrollment over
Secure Transport (EST) [RFC7030] with [RFC8366] vouchers to securely Secure Transport (EST) [RFC7030] with [RFC8366] vouchers to securely
enroll devices. A Registrar provides the security anchor of the enroll devices. A Registrar provides the security anchor of the
network to which a Pledge enrolls. In this document, BRSKI is network to which a Pledge enrolls. In this document, BRSKI is
extended such that a Pledge connects to "Registrars" via a Join extended such that a Pledge connects to "Registrars" via a
Proxy. constrained Join Proxy. In particular, the underlying IP network is
assumed to be a mesh newtork as described in [RFC4944], although
other IP-over-foo networks are not excluded.
A complete specification of the terminology is pointed at in A complete specification of the terminology is pointed at in
Section 2. Section 2.
The specified solutions in [RFC8995] and [RFC7030] are based on POST The specified solutions in [RFC8995] and [RFC7030] are based on POST
or GET requests to the EST resources (/cacerts, /simpleenroll, or GET requests to the EST resources (/cacerts, /simpleenroll,
/simplereenroll, /serverkeygen, and /csrattrs), and the brski /simplereenroll, /serverkeygen, and /csrattrs), and the brski
resources (/requestvoucher, /voucher_status, and /enrollstatus). resources (/requestvoucher, /voucher_status, and /enrollstatus).
These requests use https and may be too large in terms of code space These requests use https and may be too large in terms of code space
or bandwidth required for constrained devices. Constrained devices or bandwidth required for constrained devices. Constrained devices
skipping to change at page 3, line 49 skipping to change at page 4, line 7
CoAP can be run with the Datagram Transport Layer Security (DTLS) CoAP can be run with the Datagram Transport Layer Security (DTLS)
[RFC6347] as a security protocol for authenticity and confidentiality [RFC6347] as a security protocol for authenticity and confidentiality
of the messages. This is known as the "coaps" scheme. A constrained of the messages. This is known as the "coaps" scheme. A constrained
version of EST, using Coap and DTLS, is described in version of EST, using Coap and DTLS, is described in
[I-D.ietf-ace-coap-est]. The [I-D.ietf-anima-constrained-voucher] [I-D.ietf-ace-coap-est]. The [I-D.ietf-anima-constrained-voucher]
extends [I-D.ietf-ace-coap-est] with BRSKI artifacts such as voucher, extends [I-D.ietf-ace-coap-est] with BRSKI artifacts such as voucher,
request voucher, and the protocol extensions for constrained Pledges. request voucher, and the protocol extensions for constrained Pledges.
DTLS is a client-server protocol relying on the underlying IP layer DTLS is a client-server protocol relying on the underlying IP layer
to perform the routing between the DTLS Client and the DTLS Server. to perform the routing between the DTLS Client and the DTLS Server.
However, the Pledge will not be IP routable until it is authenticated However, the Pledge will not be IP routable over the mesh network
to the network. A new Pledge can only initially use a link-local until it is authenticated to the mesh network. A new Pledge can only
IPv6 address to communicate with a neighbor on the same link initially use a link-local IPv6 address to communicate with a mesh
[RFC6775] until it receives the necessary network configuration neighbor [RFC6775] until it receives the necessary network
parameters. However, before the Pledge can receive these configuration parameters. The Pledge receives these configuration
configuration parameters, it needs to authenticate itself to the parameters from the Registrar. When the Registrar is not a direct
network to which it connects. neighbor of the Registrar but several hops away, the Pledge discovers
a neighbor constrained Join Proxy, which transmits the DTLS protected
request coming from the Pledge to the Registrar. The constrained
Join Proxy must be enrolled previously such that the message from
constrained Join Proxy to Registrar can be routed over one or more
hops.
During enrollment, a DTLS connection is required between Pledge and During enrollment, a DTLS connection is required between Pledge and
Registrar. Registrar.
Once a Pledge is enrolled, it can act as Join Proxy between other Once a Pledge is enrolled, it can act as constrained Join Proxy
Pledges and the enrolling Registrar. between other Pledges and the enrolling Registrar.
This document specifies a new form of Join Proxy and protocol to act This document specifies a new form of constrained Join Proxy and
as intermediary between Pledge and Registrar to relay DTLS messages protocol to act as intermediary between Pledge and Registrar to relay
between Pledge and Registrar. Two versions of the Join Proxy are DTLS messages between Pledge and Registrar. Two modes of the
specified: constrained Join Proxy are specified:
1 A stateful Join Proxy that locally stores IP addresses 1 A stateful Join Proxy that locally stores IP addresses
during the connection. during the connection.
2 A stateless Join Proxy that where the connection state 2 A stateless Join Proxy that where the connection state
is stored in the messages. is stored in the messages.
This document is very much inspired by text published earlier in This document is very much inspired by text published earlier in
[I-D.kumar-dice-dtls-relay]. [I-D.kumar-dice-dtls-relay].
[I-D.richardson-anima-state-for-joinrouter] outlined the various [I-D.richardson-anima-state-for-joinrouter] outlined the various
options for building a Join Proxy. [RFC8995] adopted only the options for building a constrained Join Proxy. [RFC8995] adopted
Circuit Proxy method (1), leaving the other methods as future work. only the Circuit Proxy method (1), leaving the other methods as
This document standardizes the CoAP/DTLS (method 4). future work.
The stateful and stateless modes differ in the way that they store
the state required to forward the return packet to the pledge.
Similar to the difference between storing and non_storing Modes of
Operations (MOP) in RPL [RFC6550]. In the stateful method, the
return forward state is stored in the join proxy. In the stateless
method, the return forward state is stored in the network.
2. Terminology 2. Terminology
The following terms are defined in [RFC8366], and are used The following terms are defined in [RFC8366], and are used
identically as in that document: artifact, imprint, domain, Join identically as in that document: artifact, imprint, domain, Join
Registrar/Coordinator (JRC), Manufacturer Authorized Signing Registrar/Coordinator (JRC), Pledge, and Voucher.
Authority (MASA), Pledge, Trust of First Use (TOFU), and Voucher.
In this document, the term "Registrar" is used throughout instead of
"Join Registrar/Coordinator (JRC)".
The term "installation network" refers to all devices in the The term "installation network" refers to all devices in the
installation and the network connections between them. The term installation and the network connections between them. The term
"installation IP_address" refers to an address out of the set of "installation IP_address" refers to an address out of the set of
addresses which are routable over the whole installation network. addresses which are routable over the whole installation network.
The "Constrained Join Proxy" enables a pledge that is multiple hops
away from the Registrar, to securely execute the BRSKI protocol
[RFC8995] over a secure channel.
The term "join Proxy" is used interchangeably with the term
"constrained Join Proxy" throughout this document.
3. Requirements Language 3. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
4. Join Proxy functionality 4. constrained Join Proxy functionality
As depicted in the Figure 1, the Pledge (P), in a Low-Power and Lossy As depicted in the Figure 1, the Pledge (P), in a Low-Power and Lossy
Network (LLN) mesh [RFC7102] can be more than one hop away from the Network (LLN) mesh [RFC7102] can be more than one hop away from the
Registrar (R) and not yet authenticated into the network. Registrar (R) and not yet authenticated into the network.
In this situation, the Pledge can only communicate one-hop to its In this situation, the Pledge can only communicate one-hop to its
nearest neighbor, the Join Proxy (J) using their link-local IPv6 nearest neighbor, the constrained Join Proxy (J) using their link-
addresses. However, the Pledge (P) needs to communicate with end-to- local IPv6 addresses. However, the Pledge (P) needs to communicate
end security with a Registrar to authenticate and get the relevant with end-to-end security with a Registrar to authenticate and get the
system/network parameters. If the Pledge (P), knowing the IP-address relevant system/network parameters. If the Pledge (P), knowing the
of the Registrar, initiates a DTLS connection to the Registrar, then IP-address of the Registrar, initiates a DTLS connection to the
the packets are dropped at the Join Proxy (J) since the Pledge (P) is Registrar, then the packets are dropped at the constrained Join Proxy
not yet admitted to the network or there is no IP routability to (J) since the Pledge (P) is not yet admitted to the network or there
Pledge (P) for any returned messages from the Registrar. is no IP routability to Pledge (P) for any returned messages from the
Registrar.
++++ multi-hop ++++ multi-hop
|R |---- mesh +--+ +--+ |R |---- mesh +--+ +--+
| | \ |J |........|P | | | \ |J |........|P |
++++ \-----| | | | ++++ \-----| | | |
+--+ +--+ +--+ +--+
Registrar Join Proxy Pledge Registrar Join Proxy Pledge
Figure 1: multi-hop enrollment. Figure 1: multi-hop enrollment.
Without routing the Pledge (P) cannot establish a secure connection Without routing the Pledge (P) cannot establish a secure connection
to the Registrar (R) over multiple hops in the network. to the Registrar (R) over multiple hops in the network.
Furthermore, the Pledge (P) cannot discover the IP address of the Furthermore, the Pledge (P) cannot discover the IP address of the
Registrar (R) over multiple hops to initiate a DTLS connection and Registrar (R) over multiple hops to initiate a DTLS connection and
perform authentication. perform authentication.
To overcome the problems with non-routability of DTLS packets and/or To overcome the problems with non-routability of DTLS packets and/or
discovery of the destination address of the Registrar, the Join Proxy discovery of the destination address of the Registrar, the
is introduced. This Join Proxy functionality is configured into all constrained Join Proxy is introduced. This constrained Join Proxy
authenticated devices in the network which may act as a Join Proxy functionality is configured into all authenticated devices in the
for Pledges. The Join Proxy allows for routing of the packets from network which may act as a constrained Join Proxy for Pledges. The
the Pledge using IP routing to the intended Registrar. An constrained Join Proxy allows for routing of the packets from the
authenticated Join Proxy can discover the routable IP address of the Pledge using IP routing to the intended Registrar. An authenticated
constrained Join Proxy can discover the routable IP address of the
Registrar over multiple hops. The following Section 5 specifies the Registrar over multiple hops. The following Section 5 specifies the
two Join Proxy modes. A comparison is presented in Section 7. two constrained Join Proxy modes. A comparison is presented in
Section 7.
5. Join Proxy specification When a mesh network is set up, it consists of a Registrar and a set
of connected pledges. No constrained Join Proxies are present. The
wanted end-state is a network with a Registrar and a set of enrolled
devices. Some of these enrolled devices can act as constrained Join
Proxies. Pledges can only employ link-local communication untill
they are enrolled. A Pledge will regularly try to discover a
constrained Join Proxy or a Registrar with link-local discovery
requests. The Pledges which are neigbors of the Registrar will
discover the Registrar and be enrolled following the BRSKI protocol.
An enrolled device can act as constrained Join Proxy. The Pledges
which are not a neighbor of the Registrar will eventually discover a
constrained Join Proxy and follow the BRSKI protocol to be enrolled.
While this goes on, more and more constrained Join Proxies with a
larger hop distance to the Registrar will emerge. The network should
be configured such that at the end of the enrollment process, all
pledges have discovered a neigboring constrained Join Proxy or the
Registrar, and all "legal" Pledges are enrolled.
5. constrained Join Proxy specification
A Join Proxy can operate in two modes: A Join Proxy can operate in two modes:
* Stateful mode * Stateful mode
* Stateless mode * Stateless mode
A Join Proxy MUST implement one of the two modes. A Join Proxy MAY A Join Proxy MAY implement both. A mechanism to switch between modes
implement both, with an unspecified mechanism to switch between the is out of scope of this document. It is recommended that a Join
two modes. Proxy uses only one of these modes at any given moment during an
installation lifetime.
5.1. Stateful Join Proxy 5.1. Stateful Join Proxy
In stateful mode, the Join Proxy forwards the DTLS messages to the In stateful mode, the Join Proxy forwards the DTLS messages to the
Registrar. Registrar.
Assume that the Pledge does not know the IP address of the Registrar Assume that the Pledge does not know the IP address of the Registrar
it needs to contact. The Join Proxy has been enrolled via the it needs to contact. The Join Proxy has been enrolled via the
Registrar and learns the IP address and port of the Registrar, for Registrar and learns the IP address and port of the Registrar, for
example by using the discovery mechanism described in Section 6. The example by using the discovery mechanism described in Section 6. The
Pledge first discovers (see Section 6) and selects the most Pledge first discovers (see Section 6) and selects the most
appropriate Join Proxy. (Discovery can also be based upon [RFC8995] appropriate Join Proxy. (Discovery can also be based upon [RFC8995]
section 4.1). For service discovery via DNS-SD [RFC6763], this section 4.1). For service discovery via DNS-SD [RFC6763], this
document specifies the service names in Section 9.2. The Pledge document specifies the service names in Section 9.2. The Pledge
initiates its request as if the Join Proxy is the intended Registrar. initiates its request as if the Join Proxy is the intended Registrar.
The Join Proxy receives the message at a discoverable join-port. The The Join Proxy receives the message at a discoverable join-port. The
Join Proxy constructs an IP packet by copying the DTLS payload from Join Proxy constructs an IP packet by copying the DTLS payload from
the message received from the Pledge, and provides source and the message received from the Pledge, and provides source and
destination addresses to forward the message to the intended destination addresses to forward the message to the intended
Registrar. The Join Proxy maintains a 4-tuple array to translate the Registrar. The Join Proxy stores the 4-tuple array of the messages
DTLS messages received from the Registrar and forwards it back to the received from the Registrar and copies it back to the header of the
Pledge. message returned to the Pledge.
In Figure 2 the various steps of the message flow are shown, with In Figure 2 the various steps of the message flow are shown, with
5684 being the standard coaps port: 5684 being the standard coaps port:
+------------+------------+-------------+--------------------------+ +------------+------------+-------------+--------------------------+
| Pledge | Join Proxy | Registrar | Message | | Pledge | Join Proxy | Registrar | Message |
| (P) | (J) | (R) | Src_IP:port | Dst_IP:port| | (P) | (J) | (R) | Src_IP:port | Dst_IP:port|
+------------+------------+-------------+-------------+------------+ +------------+------------+-------------+-------------+------------+
| --ClientHello--> | IP_P:p_P | IP_Jl:p_Jl | | --ClientHello--> | IP_P:p_P | IP_Jl:p_Jl |
| --ClientHello--> | IP_Jr:p_Jr| IP_R:5684 | | --ClientHello--> | IP_Jr:p_Jr| IP_R:5684 |
skipping to change at page 10, line 36 skipping to change at page 11, line 36
On reception by the Registrar, the Registrar MUST verify that the On reception by the Registrar, the Registrar MUST verify that the
number of array elements is larger than or equal to 5, and reject the number of array elements is larger than or equal to 5, and reject the
message when the number of array elements is smaller than 5. After message when the number of array elements is smaller than 5. After
replacing the 5th "content" element with the DTLS payload of the replacing the 5th "content" element with the DTLS payload of the
response message and leaving all other array elements unchanged, the response message and leaving all other array elements unchanged, the
Registrar returns the response message. Registrar returns the response message.
Examples are shown in Appendix A. Examples are shown in Appendix A.
When additions are added to the array in later versions of this The header field is completely opaque to the receiver. A Registrar
protocol, any additional array elements (i.e., not specified by MUST copy the header and return it unmodified in the return message.
current document) MUST be ignored by a receiver if it doesn't know
these elements. This approach allows evolution of the protocol while
maintaining backwards-compatibility. A version number isn't needed;
that number is defined by the length of the array. However, this
means that message elements are consistently added to earlier defined
elements to avoid ambiguities.
6. Discovery 6. Discovery
It is assumed that Join Proxy seamlessly provides a coaps connection It is assumed that Join Proxy seamlessly provides a coaps connection
between Pledge and Registrar. In particular this section extends between Pledge and Registrar. In particular this section extends
section 4.1 of [RFC8995] for the constrained case. section 4.1 of [RFC8995] for the constrained case.
The discovery follows two steps with two alternatives for step 1: The discovery follows two steps with two alternatives for step 1:
* Step 1. Two alternatives exist (near and remote): * Step 1. Two alternatives exist (near and remote):
skipping to change at page 11, line 23 skipping to change at page 12, line 21
- Remote: the Pledge is more than one hop away from a relevant - Remote: the Pledge is more than one hop away from a relevant
Registrar, and discovers the link-local address and join-port Registrar, and discovers the link-local address and join-port
of a Join Proxy. The Pledge then follows the BRSKI procedure of a Join Proxy. The Pledge then follows the BRSKI procedure
using the link-local address of the Join Proxy. using the link-local address of the Join Proxy.
* Step 2. The enrolled Join Proxy discovers the join-port of the * Step 2. The enrolled Join Proxy discovers the join-port of the
Registrar. Registrar.
The order in which the two alternatives of step 1 are tried is The order in which the two alternatives of step 1 are tried is
installation dependent. The trigger for discovery in Step 2 in installation dependent. The trigger for discovery in Step 2 is
implementation dependent. implementation dependent.
Once a Pledge is enrolled, it may function as Join Proxy. The Join Once a Pledge is enrolled, it may function as Join Proxy. The Join
Proxy functions are advertised as described below. In principle, the Proxy functions are advertised as described below. In principle, the
Join Proxy functions are offered via a join-port, and not the Join Proxy functions are offered via a join-port, and not the
standard coaps port. Also, the Registrar offers a join-port to which standard coaps port. Also, the Registrar offers a join-port to which
the stateless Join Proxy sends the JPY message. The Join Proxy and the stateless Join Proxy sends the JPY message. The Join Proxy and
Registrar show the extra join-port number when responding to a Registrar show the extra join-port number when responding to a
/.well-known/core discovery request addressed to the standard coap/ /.well-known/core discovery request addressed to the standard coap/
coaps port. coaps port.
Three discovery cases are discussed: Join Proxy discovers Registrar, Three discovery cases are discussed: Join Proxy discovers Registrar,
Pledge discovers Registrar, and Pledge discovers Join Proxy. Each Pledge discovers Registrar, and Pledge discovers Join Proxy. Each
discovery case considers three alternatives: CoAP based discovery, discovery case considers three alternatives: CoAP based discovery,
GRASP Based discovery, and 6tisch based discovery. The choice of GRASP Based discovery, and 6tisch based discovery. The choice of
discovery mechanism depends on the type of installation, and discovery mechanism depends on the type of installation, and
manufacturers can provide the pledge/join-proxy with support for more manufacturers can provide the pledge/Join Proxy with support for more
than one discovery mechanism. The pledge/join-proxy can be designed than one discovery mechanism. The pledge/Join Proxy can be designed
to dynamically try different discovery mechanisms until a successful to dynamically try different discovery mechanisms until a successful
discovery mechanism is found, or the choice of discovery mechanism discovery mechanism is found, or the choice of discovery mechanism
could be configured during device installation. could be configured during device installation.
6.1. Join Proxy discovers Registrar 6.1. Join Proxy discovers Registrar
In this section, the Join Proxy and Registrar are assumed to In this section, the Join Proxy and Registrar are assumed to
communicate via Link-Local addresses. This section describes the communicate via Link-Local addresses. This section describes the
discovery of the Registrar by the Join Proxy. discovery of the Registrar by the Join Proxy.
skipping to change at page 15, line 13 skipping to change at page 16, line 13
Figure 5: Comparison between stateful and stateless mode Figure 5: Comparison between stateful and stateless mode
8. Security Considerations 8. Security Considerations
All the concerns in [RFC8995] section 4.1 apply. The Pledge can be All the concerns in [RFC8995] section 4.1 apply. The Pledge can be
deceived by malicious Join Proxy announcements. The Pledge will only deceived by malicious Join Proxy announcements. The Pledge will only
join a network to which it receives a valid [RFC8366] voucher join a network to which it receives a valid [RFC8366] voucher
[I-D.ietf-anima-constrained-voucher]. Once the Pledge joined, the [I-D.ietf-anima-constrained-voucher]. Once the Pledge joined, the
payload between Pledge and Registrar is protected by DTLS. payload between Pledge and Registrar is protected by DTLS.
It should be noted here that the contents of the CBOR map used to A malicious constrained Join Proxy has a number of routing
possibilities:
* It sends the message on to a malicious Registrar. This is the
same case as the presence of a malicious Registrar discussed in
RFC 8995.
* It does not send on the request or does not return the response
from the Registrar. This is the case of the not responding or
crashing Registrar discussed in RFC 8995.
* It uses the returned response of the Registrar to enroll itself in
the network. With very low probability it can decrypt the
response. Successful enrollment is deemed too unlikely.
* It uses the request from the pledge to appropriate the pledge
certificate, but then it still needs to acquire the private key of
the pledge. Also this is assumed to be highly unlikely.
* A malicious node can construct an invalid Join Proxy message.
Suppose, the destination port is the coaps port. In that case, a
Join Proxy can accept the message and add the routing addresses
without checking the payload. The Join Proxy then routes it to
the Registrar. In all cases, the Registrar needs to receive the
message at the join-port, checks that the message consists of two
parts and uses the DTLS payload to start the BRSKI procedure. It
is highly unlikely that this malicious payload will lead to node
acceptance.
* A malicious node can sniff the messages routed by the constrained
Join Proxy. It is very unlikely that the malicious node can
decrypt the DTLS payload. A malicious node can read the header
field of the message sent by the stateless Join Proxy. This
ability does not yield much more information than the visible
addresses transported in the network packets.
It should be noted here that the contents of the CBOR array used to
convey return address information is not DTLS protected. When the convey return address information is not DTLS protected. When the
communication between JOIN Proxy and Registrar passes over an communication between JOIN Proxy and Registrar passes over an
unsecure network, an attacker can change the CBOR array, causing the unsecure network, an attacker can change the CBOR array, causing the
Registrar to deviate traffic from the intended Pledge. If such Registrar to deviate traffic from the intended Pledge. These
scenario needs to be avoided, then it is reasonable for the Join concerns are also expressed in [RFC8974]. It is also pointed out
Proxy to encrypt the CBOR array using a locally generated symmetric that the encryption in the source is a local matter. Similarly to
key. The Registrar would not be able to examine the result, but it [RFC8974], the use of AES-CCM [RFC3610] with a 64-bit tag is
does not need to do so. This is a topic for future work. recommended, combined with a sequence number and a replay window.
In some installations, level 2 protection is provided between all If such scenario needs to be avoided, the constrained Join Proxy MUST
encrypt the CBOR array using a locally generated symmetric key. The
Registrar is not able to examine the encrypted result, but does not
need to. The Registrar stores the encrypted header in the return
packet without modifications. The constrained Join Proxy can decrypt
the contents to route the message to the right destination.
In some installations, layer 2 protection is provided between all
member pairs of the mesh. In such an enviroment encryption of the member pairs of the mesh. In such an enviroment encryption of the
CBOR array is unnecessay because the level 2 protection already CBOR array is unnecessay because the layer 2 protection already
provide it. provide it.
9. IANA Considerations 9. IANA Considerations
9.1. Resource Type Attributes registry 9.1. Resource Type Attributes registry
This specification registers two new Resource Type (rt=) Link Target This specification registers two new Resource Type (rt=) Link Target
Attributes in the "Resource Type (rt=) Link Target Attribute Values" Attributes in the "Resource Type (rt=) Link Target Attribute Values"
subregistry under the "Constrained RESTful Environments (CoRE) subregistry under the "Constrained RESTful Environments (CoRE)
Parameters" registry per the [RFC6690] procedure. Parameters" registry per the [RFC6690] procedure.
Attribute Value: brski.jp Attribute Value: brski.jp
Description: This BRSKI resource type is used to query and return the Description: This BRSKI resource type is used to query and return
supported BRSKI (CoAP over DTLS) port of the constrained the supported BRSKI resources of the constrained
Join Proxy. Join Proxy.
Reference: [this document] Reference: [this document]
Attribute Value: brski.rjp Attribute Value: brski.rjp
Description: This BRSKI resource type is used to query and return the Description: This BRSKI resource type is used for the constrained
supported BRSKI JPY protocol port of the Registrar. Join Proxy to query and return Join Proxy specific
BRSKI resources of a Registrar.
Reference: [this document] Reference: [this document]
9.2. service name and port number registry 9.2. service name and port number registry
This specification registers two service names under the "Service This specification registers two service names under the "Service
Name and Transport Protocol Port Number" registry. Name and Transport Protocol Port Number" registry.
Service Name: brski-jp Service Name: brski-jp
Transport Protocol(s): udp Transport Protocol(s): udp
Assignee: IESG <iesg@ietf.org> Assignee: IESG <iesg@ietf.org>
skipping to change at page 16, line 24 skipping to change at page 18, line 24
Transport Protocol(s): udp Transport Protocol(s): udp
Assignee: IESG <iesg@ietf.org> Assignee: IESG <iesg@ietf.org>
Contact: IESG <iesg@ietf.org> Contact: IESG <iesg@ietf.org>
Description: Bootstrapping Remote Secure Key Infrastructure Description: Bootstrapping Remote Secure Key Infrastructure
Registrar join-port used by stateless constrained Registrar join-port used by stateless constrained
Join Proxy Join Proxy
Reference: [this document] Reference: [this document]
10. Acknowledgements 10. Acknowledgements
Many thanks for the comments by Brian Carpenter, Esko Dijk, Russ Many thanks for the comments by Cartsen, Bormann, Brian Carpenter,
Housley, and Rob Wilton. Esko Dijk, Toerless Eckert, Russ Housley, Ines Robles, Juergen
Schoenwaelder, Malisa Vu&#269;ini&#263;, and Rob Wilton.
11. Contributors 11. Contributors
Sandeep Kumar, Sye loong Keoh, and Oscar Garcia-Morchon are the co- Sandeep Kumar, Sye loong Keoh, and Oscar Garcia-Morchon are the co-
authors of the draft-kumar-dice-dtls-relay-02. Their draft has authors of the draft-kumar-dice-dtls-relay-02. Their draft has
served as a basis for this document. Much text from their draft is served as a basis for this document. Much text from their draft is
copied over to this draft. copied over to this draft.
12. Changelog 12. Changelog
12.1. 06 to 07 12.1. 10 to 09
* OPSDIR review
* IANA review
* SECDIR review
* GENART review
12.2. 09 to 07
* typos
12.3. 06 to 07
* AD review changes * AD review changes
12.2. 05 to 06 12.4. 05 to 06
* RT value change to brski.jp and brski.rjp * RT value change to brski.jp and brski.rjp
* new registry values for IANA * new registry values for IANA
* improved handling of jpy header array * improved handling of jpy header array
12.3. 04 to 05 12.5. 04 to 05
* Join Proxy and join-port consistent spelling * Join Proxy and join-port consistent spelling
* some nits removed * some nits removed
* restructured discovery * restructured discovery
* section * section
* rephrased parts of security section * rephrased parts of security section
12.4. 03 to 04 12.6. 03 to 04
* mail address and reference * mail address and reference
12.5. 02 to 03 12.7. 02 to 03
* Terminology updated * Terminology updated
* Several clarifications on discovery and routability * Several clarifications on discovery and routability
* DTLS payload introduced * DTLS payload introduced
12.6. 01 to 02 12.8. 01 to 02
* Discovery of Join Proxy and Registrar ports * Discovery of Join Proxy and Registrar ports
12.7. 00 to 01 12.9. 00 to 01
* Registrar used throughout instead of EST server * Registrar used throughout instead of EST server
* Emphasized additional Join Proxy port for Join Proxy and Registrar * Emphasized additional Join Proxy port for Join Proxy and Registrar
* updated discovery accordingly * updated discovery accordingly
* updated stateless Join Proxy JPY header * updated stateless Join Proxy JPY header
* JPY header described with CDDL * JPY header described with CDDL
* Example simplified and corrected * Example simplified and corrected
12.8. 00 to 00 12.10. 00 to 00
* copied from vanderstok-anima-constrained-join-proxy-05 * copied from vanderstok-anima-constrained-join-proxy-05
13. References 13. References
13.1. Normative References 13.1. Normative References
[family] "Address Family Numbers", 19 October 2021, [family] "Address Family Numbers", 19 October 2021,
<https://www.iana.org/assignments/address-family-numbers/ <https://www.iana.org/assignments/address-family-numbers/
address-family-numbers.xhtml>. address-family-numbers.xhtml>.
[I-D.ietf-ace-coap-est] [I-D.ietf-ace-coap-est]
Stok, P. V. D., Kampanakis, P., Richardson, M. C., and S. Stok, P. V. D., Kampanakis, P., Richardson, M. C., and S.
Raza, "EST over secure CoAP (EST-coaps)", Work in Raza, "EST over secure CoAP (EST-coaps)", Work in
Progress, Internet-Draft, draft-ietf-ace-coap-est-18, 6 Progress, Internet-Draft, draft-ietf-ace-coap-est-18, 6
January 2020, <https://www.ietf.org/archive/id/draft-ietf- January 2020, <https://www.ietf.org/archive/id/draft-ietf-
ace-coap-est-18.txt>. ace-coap-est-18.txt>.
[I-D.ietf-anima-constrained-voucher] [I-D.ietf-anima-constrained-voucher]
Richardson, M., Stok, P. V. D., Kampanakis, P., and E. Richardson, M., Stok, P. V. D., Kampanakis, P., and E.
Dijk, "Constrained Bootstrapping Remote Secure Key Dijk, "Constrained Bootstrapping Remote Secure Key
Infrastructure (BRSKI)", Work in Progress, Internet-Draft, Infrastructure (BRSKI)", Work in Progress, Internet-Draft,
draft-ietf-anima-constrained-voucher-16, 14 February 2022, draft-ietf-anima-constrained-voucher-17, 7 April 2022,
<https://www.ietf.org/archive/id/draft-ietf-anima- <https://www.ietf.org/archive/id/draft-ietf-anima-
constrained-voucher-16.txt>. constrained-voucher-17.txt>.
[ieee802-1AR] [ieee802-1AR]
"IEEE 802.1AR Secure Device Identifier", 2009, "IEEE 802.1AR Secure Device Identifier", 2009,
<https://standards.ieee.org/standard/802.1AR-2009.html>. <https://standards.ieee.org/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,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 19, line 28 skipping to change at page 21, line 40
dtls-relay-02.txt>. dtls-relay-02.txt>.
[I-D.richardson-anima-state-for-joinrouter] [I-D.richardson-anima-state-for-joinrouter]
Richardson, M. C., "Considerations for stateful vs Richardson, M. C., "Considerations for stateful vs
stateless join router in ANIMA bootstrap", Work in stateless join router in ANIMA bootstrap", Work in
Progress, Internet-Draft, draft-richardson-anima-state- Progress, Internet-Draft, draft-richardson-anima-state-
for-joinrouter-03, 22 September 2020, for-joinrouter-03, 22 September 2020,
<https://www.ietf.org/archive/id/draft-richardson-anima- <https://www.ietf.org/archive/id/draft-richardson-anima-
state-for-joinrouter-03.txt>. state-for-joinrouter-03.txt>.
[RFC3610] Whiting, D., Housley, R., and N. Ferguson, "Counter with
CBC-MAC (CCM)", RFC 3610, DOI 10.17487/RFC3610, September
2003, <https://www.rfc-editor.org/info/rfc3610>.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4 "Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<https://www.rfc-editor.org/info/rfc4944>. <https://www.rfc-editor.org/info/rfc4944>.
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>.
[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link [RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
Format", RFC 6690, DOI 10.17487/RFC6690, August 2012, Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
<https://www.rfc-editor.org/info/rfc6690>. <https://www.rfc-editor.org/info/rfc6690>.
[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,
<https://www.rfc-editor.org/info/rfc6763>. <https://www.rfc-editor.org/info/rfc6763>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over Bormann, "Neighbor Discovery Optimization for IPv6 over
skipping to change at page 20, line 19 skipping to change at page 22, line 45
[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,
<https://www.rfc-editor.org/info/rfc7228>. <https://www.rfc-editor.org/info/rfc7228>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252, Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014, DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/info/rfc7252>. <https://www.rfc-editor.org/info/rfc7252>.
[RFC8974] Hartke, K. and M. Richardson, "Extended Tokens and
Stateless Clients in the Constrained Application Protocol
(CoAP)", RFC 8974, DOI 10.17487/RFC8974, January 2021,
<https://www.rfc-editor.org/info/rfc8974>.
Appendix A. Stateless Proxy payload examples Appendix A. Stateless Proxy payload examples
The examples show the request "GET coaps://192.168.1.200:5965/est/ The examples show the request "GET coaps://192.168.1.200:5965/est/
crts" to a Registrar. The header generated between Join Proxy and crts" to a Registrar. The header generated between Join Proxy and
Registrar and from Registrar to Join Proxy are shown in detail. The Registrar and from Registrar to Join Proxy are shown in detail. The
DTLS payload is not shown. DTLS payload is not shown.
The request from Join Proxy to Registrar looks like: The request from Join Proxy to Registrar looks like:
85 # array(5) 85 # array(5)
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