< draft-ietf-ipsecme-rfc4307bis-09.txt   draft-ietf-ipsecme-rfc4307bis-10.txt >
Network Working Group Y. Nir Network Working Group Y. Nir
Internet-Draft Check Point Internet-Draft Check Point
Obsoletes: 4307 (if approved) T. Kivinen Obsoletes: 4307 (if approved) T. Kivinen
Updates: 7296 (if approved) INSIDE Secure Updates: 7296 (if approved) INSIDE Secure
Intended status: Standards Track P. Wouters Intended status: Standards Track P. Wouters
Expires: November 14, 2016 Red Hat Expires: January 21, 2017 Red Hat
D. Migault D. Migault
Ericsson Ericsson
May 13, 2016 July 20, 2016
Algorithm Implementation Requirements and Usage Guidance for IKEv2 Algorithm Implementation Requirements and Usage Guidance for IKEv2
draft-ietf-ipsecme-rfc4307bis-09 draft-ietf-ipsecme-rfc4307bis-10
Abstract Abstract
The IPsec series of protocols makes use of various cryptographic The IPsec series of protocols makes use of various cryptographic
algorithms in order to provide security services. The Internet Key algorithms in order to provide security services. The Internet Key
Exchange (IKE) protocol is used to negotiate the IPsec Security Exchange (IKE) protocol is used to negotiate the IPsec Security
Association (IPsec SA) parameters, such as which algorithms should be Association (IPsec SA) parameters, such as which algorithms should be
used. To ensure interoperability between different implementations, used. To ensure interoperability between different implementations,
it is necessary to specify a set of algorithm implementation it is necessary to specify a set of algorithm implementation
requirements and usage guidance to ensure that there is at least one requirements and usage guidance to ensure that there is at least one
algorithm that all implementations support. This document defines algorithm that all implementations support. This document defines
the current algorithm implementation requirements and usage guidance the current algorithm implementation requirements and usage guidance
for IKEv2. This document does not update the algorithms used for for IKEv2 and does minor cleaning up of IKEv2 IANA registry. This
packet encryption using IPsec Encapsulated Security Payload (ESP). document does not update the algorithms used for packet encryption
using IPsec Encapsulated Security Payload (ESP).
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 14, 2016. This Internet-Draft will expire on January 21, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3.2. Type 2 - IKEv2 Pseudo-random Function Transforms . . . . 7 3.2. Type 2 - IKEv2 Pseudo-random Function Transforms . . . . 7
3.3. Type 3 - IKEv2 Integrity Algorithm Transforms . . . . . . 8 3.3. Type 3 - IKEv2 Integrity Algorithm Transforms . . . . . . 8
3.4. Type 4 - IKEv2 Diffie-Hellman Group Transforms . . . . . 9 3.4. Type 4 - IKEv2 Diffie-Hellman Group Transforms . . . . . 9
4. IKEv2 Authentication . . . . . . . . . . . . . . . . . . . . 10 4. IKEv2 Authentication . . . . . . . . . . . . . . . . . . . . 10
4.1. IKEv2 Authentication Method . . . . . . . . . . . . . . . 10 4.1. IKEv2 Authentication Method . . . . . . . . . . . . . . . 10
4.1.1. Recommendations for RSA key length . . . . . . . . . 11 4.1.1. Recommendations for RSA key length . . . . . . . . . 11
4.2. Digital Signature Recommendations . . . . . . . . . . . . 12 4.2. Digital Signature Recommendations . . . . . . . . . . . . 12
5. Algorithms for Internet of Things . . . . . . . . . . . . . . 12 5. Algorithms for Internet of Things . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . 14 9.1. Normative References . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . 15 9.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
The Internet Key Exchange (IKE) protocol [RFC7296] is used to The Internet Key Exchange (IKE) protocol [RFC7296] is used to
negotiate the parameters of the IPsec SA, such as the encryption and negotiate the parameters of the IPsec SA, such as the encryption and
authentication algorithms and the keys for the protected authentication algorithms and the keys for the protected
communications between the two endpoints. The IKE protocol itself is communications between the two endpoints. The IKE protocol itself is
also protected by cryptographic algorithms which are negotiated also protected by cryptographic algorithms which are negotiated
between the two endpoints using IKE. Different implementations of between the two endpoints using IKE. Different implementations of
IKE may negotiate different algorithms based on their individual IKE may negotiate different algorithms based on their individual
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3.1. Type 1 - IKEv2 Encryption Algorithm Transforms 3.1. Type 1 - IKEv2 Encryption Algorithm Transforms
The algorithms in the below table are negotiated in the SA payload The algorithms in the below table are negotiated in the SA payload
and used for the Encrypted Payload. References to the specification and used for the Encrypted Payload. References to the specification
defining these algorithms and the ones in the following subsections defining these algorithms and the ones in the following subsections
are in the IANA registry [IKEV2-IANA]. Some of these algorithms are are in the IANA registry [IKEV2-IANA]. Some of these algorithms are
Authenticated Encryption with Associated Data (AEAD - [RFC5282]). Authenticated Encryption with Associated Data (AEAD - [RFC5282]).
Algorithms that are not AEAD MUST be used in conjunction with an Algorithms that are not AEAD MUST be used in conjunction with an
integrity algorithms in Section 3.3. integrity algorithms in Section 3.3.
+-----------------------------+----------+-------+----------+ +------------------------+----------+-------+----------+
| Name | Status | AEAD? | Comment | | Name | Status | AEAD? | Comment |
+-----------------------------+----------+-------+----------+ +------------------------+----------+-------+----------+
| ENCR_AES_CBC | MUST- | No | [1] | | ENCR_AES_CBC | MUST | No | [1] |
| ENCR_CHACHA20_POLY1305 | SHOULD | Yes | | | ENCR_CHACHA20_POLY1305 | SHOULD | Yes | |
| AES-GCM with a 16 octet ICV | SHOULD | Yes | [1] | | ENCR_AES_GCM_16 | SHOULD | Yes | [1] |
| ENCR_AES_CCM_8 | SHOULD | Yes | [1][IoT] | | ENCR_AES_CCM_8 | SHOULD | Yes | [1][IoT] |
| ENCR_3DES | MAY | No | | | ENCR_3DES | MAY | No | |
| ENCR_DES | MUST NOT | No | | | ENCR_DES | MUST NOT | No | |
+-----------------------------+----------+-------+----------+ +------------------------+----------+-------+----------+
[1] - This requirement level is for 128-bit keys. 256-bit keys are at [1] - This requirement level is for 128-bit keys. 256-bit keys are at
SHOULD. 192-bit keys can safely be ignored. [IoT] - This requirement SHOULD. 192-bit keys can safely be ignored. [IoT] - This requirement
is for interoperability with IoT. is for interoperability with IoT.
ENCR_AES_CBC is raised from SHOULD+ in [RFC4307] to MUST. It is the ENCR_AES_CBC is raised from SHOULD+ in [RFC4307] to MUST. It is the
only shared mandatory-to-implement algorithm with RFC4307 and as a only shared mandatory-to-implement algorithm with RFC4307 and as a
result it is necessary for interoperability with IKEv2 implementation result it is necessary for interoperability with IKEv2 implementation
compatible with RFC4307. compatible with RFC4307.
ENCR_CHACHA20_POLY1305 was not ready to be considered at the time of ENCR_CHACHA20_POLY1305 was not ready to be considered at the time of
RFC4307. It has been recommended by the CRFG and others as an RFC4307. It has been recommended by the CRFG and others as an
alternative to AES-CBC and AES-GCM. It is also being standardized alternative to AES-CBC and AES-GCM. It is also being standardized
for IPsec for the same reasons. At the time of writing, there were for IPsec for the same reasons. At the time of writing, there were
not enough IKEv2 implementations supporting ENCR_CHACHA20_POLY1305 to not enough IKEv2 implementations supporting ENCR_CHACHA20_POLY1305 to
be able to introduce it at the SHOULD+ level. be able to introduce it at the SHOULD+ level.
AES-GCM with a 16 octet ICV was not considered in RFC4307. At the ENCR_AES_GCM_16 was not considered in RFC4307. At the time RFC4307
time RFC4307 was written, AES-GCM was not defined in an IETF was written, AES-GCM was not defined in an IETF document. AES-GCM
document. AES-GCM was defined for ESP in [RFC4106] and later for was defined for ESP in [RFC4106] and later for IKEv2 in [RFC5282].
IKEv2 in [RFC5282]. The main motivation for adopting AES-GCM for ESP The main motivation for adopting AES-GCM for ESP is encryption
is encryption performance and key longevity compared to AES-CBC. performance and key longevity compared to AES-CBC. This resulted in
This resulted in AES-GCM being widely implemented for ESP. As the AES-GCM being widely implemented for ESP. As the computation load of
computation load of IKEv2 is relatively small compared to ESP, many IKEv2 is relatively small compared to ESP, many IKEv2 implementations
IKEv2 implementations have not implemented AES-GCM. For this reason, have not implemented AES-GCM. For this reason, AES-GCM is not
AES-GCM is not promoted to a greater status than SHOULD. The reason promoted to a greater status than SHOULD. The reason for promotion
for promotion from MAY to SHOULD is to promote the slightly more from MAY to SHOULD is to promote the slightly more secure AEAD method
secure AEAD method over the traditional encrypt+auth method. Its over the traditional encrypt+auth method. Its status is expected to
status is expected to be raised once widely implemented. As the be raised once widely implemented. As the advantage of the shorter
advantage of the shorter (and weaker) ICVs is minimal, the 8 and 12 (and weaker) ICVs is minimal, the 8 and 12 octet ICV's remain at the
octet ICV's remain at the MAY level. MAY level.
ENCR_AES_CCM_8 was not considered in RFC4307. This document ENCR_AES_CCM_8 was not considered in RFC4307. This document
considers it as SHOULD be implemented in order to be able to interact considers it as SHOULD be implemented in order to be able to interact
with Internet of Things devices. As this case is not a general use with Internet of Things devices. As this case is not a general use
case for non-IoT VPNs, its status is expected to remain as SHOULD. case for non-IoT VPNs, its status is expected to remain as SHOULD.
The 8 octet size of the ICV is expected to be sufficient for most use The 8 octet size of the ICV is expected to be sufficient for most use
cases of IKEv2, as far less packets are exchanged on those cases, and cases of IKEv2, as far less packets are exchanged on those cases, and
IoT devices want to make packets as small as possible. When IoT devices want to make packets as small as possible. When
implemented, ENCR_AES_CCM_8 MUST be implemented for key length 128 implemented, ENCR_AES_CCM_8 MUST be implemented for key length 128
and MAY be implemented for key length 256. and MAY be implemented for key length 256.
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"mandatory-to-implement" algorithms. The algorithms identified in "mandatory-to-implement" algorithms. The algorithms identified in
this document as "MUST implement" or "SHOULD implement" are not known this document as "MUST implement" or "SHOULD implement" are not known
to be broken at the current time, and cryptographic research so far to be broken at the current time, and cryptographic research so far
leads us to believe that they will likely remain secure into the leads us to believe that they will likely remain secure into the
foreseeable future. However, this isn't necessarily forever and it foreseeable future. However, this isn't necessarily forever and it
is expected that new revisions of this document will be issued from is expected that new revisions of this document will be issued from
time to time to reflect the current best practice in this area. time to time to reflect the current best practice in this area.
7. IANA Considerations 7. IANA Considerations
This document makes no requests of IANA. This document renames some of the names in the "Transform Type 1 -
Encryption Algorithm Transform IDs" registry of the "Internet Key
Exchange Version 2 (IKEv2) Parameters". All the other names have
ENCR_ prefix except 3, and all other entries use names in format of
uppercase words separated with underscores except 6. This document
changes those names to match others.
This document requests IANA to rename following entries:
+---------------------------------------+----------------------+
| Old name | New name |
+---------------------------------------+----------------------+
| AES-GCM with a 8 octet ICV | ENCR_AES_GCM_8 |
| AES-GCM with a 12 octet ICV | ENCR_AES_GCM_12 |
| AES-GCM with a 16 octet ICV | ENCR_AES_GCM_16 |
| ENCR_CAMELLIA_CCM with an 8-octet ICV | ENCR_CAMELLIA_CCM_8 |
| ENCR_CAMELLIA_CCM with a 12-octet ICV | ENCR_CAMELLIA_CCM_12 |
| ENCR_CAMELLIA_CCM with a 16-octet ICV | ENCR_CAMELLIA_CCM_16 |
+---------------------------------------+----------------------+
In addition to add this RFC as reference to both ESP Reference and
IKEv2 Reference columns for ENCR_AES_GCM entries, keeping the current
references there also, and also add this RFC as reference to the ESP
Reference column for ENCR_CAMELLIA_CCM entries, keeping the current
reference there also.
The final registry entries should be:
Number Name ESP Reference IKEv2 Reference
...
18 ENCR_AES_GCM_8 [RFC4106][RFCXXXX] [RFC5282][RFCXXXX]
19 ENCR_AES_GCM_12 [RFC4106][RFCXXXX] [RFC5282][RFCXXXX]
20 ENCR_AES_GCM_16 [RFC4106][RFCXXXX] [RFC5282][RFCXXXX]
...
25 ENCR_CAMELLIA_CCM_8 [RFC5529][RFCXXXX] -
26 ENCR_CAMELLIA_CCM_12 [RFC5529][RFCXXXX] -
27 ENCR_CAMELLIA_CCM_16 [RFC5529][RFCXXXX] -
8. Acknowledgements 8. Acknowledgements
The first version of this document was RFC 4307 by Jeffrey I. The first version of this document was RFC 4307 by Jeffrey I.
Schiller of the Massachusetts Institute of Technology (MIT). Much of Schiller of the Massachusetts Institute of Technology (MIT). Much of
the original text has been copied verbatim. the original text has been copied verbatim.
We would like to thank Paul Hoffman, Yaron Sheffer, John Mattsson and We would like to thank Paul Hoffman, Yaron Sheffer, John Mattsson and
Tommy Pauly for their valuable feedback. Tommy Pauly for their valuable feedback.
 End of changes. 10 change blocks. 
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