5289
PROPOSED STANDARD
TLS Elliptic Curve Cipher Suites with SHA-256/384 and AES Galois Counter Mode (GCM)
Authors: E. Rescorla
Date: August 2008
Area: sec
Working Group: tls
Stream: IETF
Abstract
RFC 4492 describes elliptic curve cipher suites for Transport Layer Security (TLS). However, all those cipher suites use HMAC-SHA-1 as their Message Authentication Code (MAC) algorithm. This document describes sixteen new cipher suites for TLS that specify stronger MAC algorithms. Eight use Hashed Message Authentication Code (HMAC) with SHA-256 or SHA-384, and eight use AES in Galois Counter Mode (GCM). This memo provides information for the Internet community.
RFC 5289
PROPOSED STANDARD
Network Working Group E. Rescorla
Request for Comments: 5289 RTFM, Inc.
Category: Informational August 2008
<span class="h1">TLS Elliptic Curve Cipher Suites with</span>
<span class="h1">SHA-256/384 and AES Galois Counter Mode (GCM)</span>
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Abstract
<a href="./rfc4492">RFC 4492</a> describes elliptic curve cipher suites for Transport Layer
Security (TLS). However, all those cipher suites use HMAC-SHA-1 as
their Message Authentication Code (MAC) algorithm. This document
describes sixteen new cipher suites for TLS that specify stronger MAC
algorithms. Eight use Hashed Message Authentication Code (HMAC) with
SHA-256 or SHA-384, and eight use AES in Galois Counter Mode (GCM).
Table of Contents
<a href="#section-1">1</a>. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-2">2</a>
<a href="#section-2">2</a>. Conventions Used in This Document . . . . . . . . . . . . . . . <a href="#page-2">2</a>
<a href="#section-3">3</a>. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-2">2</a>
<a href="#section-3.1">3.1</a>. HMAC-Based Cipher Suites . . . . . . . . . . . . . . . . . <a href="#page-2">2</a>
<a href="#section-3.2">3.2</a>. Galois Counter Mode-Based Cipher Suites . . . . . . . . . . <a href="#page-3">3</a>
<a href="#section-4">4</a>. Security Considerations . . . . . . . . . . . . . . . . . . . . <a href="#page-3">3</a>
<a href="#section-5">5</a>. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . <a href="#page-3">3</a>
<a href="#section-6">6</a>. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-7">7</a>. References . . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-7.1">7.1</a>. Normative References . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-7.2">7.2</a>. Informative References . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<span class="grey">Rescorla Informational [Page 1]</span><span id="page-2" ></span>
<span class="grey"><a href="./rfc5289">RFC 5289</a> TLS ECC New MAC August 2008</span>
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Introduction</span>
<a href="./rfc4492">RFC 4492</a> [<a href="./rfc4492" title=""Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS)"">RFC4492</a>] describes Elliptic Curve Cryptography (ECC) cipher
suites for Transport Layer Security (TLS). However, all of the <a href="./rfc4492">RFC</a>
<a href="./rfc4492">4492</a> suites use HMAC-SHA1 as their MAC algorithm. Due to recent
analytic work on SHA-1 [<a href="#ref-Wang05" title=""Finding Collisions in the Full SHA-1"">Wang05</a>], the IETF is gradually moving away
from SHA-1 and towards stronger hash algorithms. This document
specifies TLS ECC cipher suites that use SHA-256 and SHA-384 [<a href="#ref-SHS" title=""Secure Hash Standard"">SHS</a>]
rather than SHA-1.
TLS 1.2 [<a href="./rfc5246" title=""The Transport Layer Security (TLS) Protocol Version 1.2"">RFC5246</a>], adds support for authenticated encryption with
additional data (AEAD) cipher modes [<a href="./rfc5116" title=""An Interface and Algorithms for Authenticated Encryption"">RFC5116</a>]. This document also
specifies a set of ECC cipher suites using one such mode, Galois
Counter Mode (GCM) [<a href="#ref-GCM" title=""Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) for Confidentiality and Authentication"">GCM</a>]. Another document [<a href="./rfc5288" title=""AES-GCM Cipher Suites for TLS"">RFC5288</a>] provides
support for GCM with other key establishment methods.
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Conventions Used in This Document</span>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [<a href="./rfc2119" title=""Key words for use in RFCs to Indicate Requirement Levels"">RFC2119</a>].
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Cipher Suites</span>
This document defines 16 new cipher suites to be added to TLS. All
use Elliptic Curve Cryptography for key exchange and digital
signature, as defined in <a href="./rfc4492">RFC 4492</a>.
<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>. HMAC-Based Cipher Suites</span>
The first eight cipher suites use AES [<a href="#ref-AES" title=""Specification for the Advanced Encryption Standard (AES)"">AES</a>] in Cipher Block Chaining
(CBC) [<a href="#ref-CBC" title=""Recommendation for Block Cipher Modes of Operation - Methods and Techniques"">CBC</a>] mode with an HMAC-based MAC:
CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 = {0xC0,0x23};
CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 = {0xC0,0x24};
CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 = {0xC0,0x25};
CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 = {0xC0,0x26};
CipherSuite TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 = {0xC0,0x27};
CipherSuite TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 = {0xC0,0x28};
CipherSuite TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256 = {0xC0,0x29};
CipherSuite TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384 = {0xC0,0x2A};
These eight cipher suites are the same as the corresponding cipher
suites in <a href="./rfc4492">RFC 4492</a> (with names ending in "_SHA" in place of "_SHA256"
or "_SHA384"), except for the MAC and Pseudo Random Function (PRF)
algorithms.
<span class="grey">Rescorla Informational [Page 2]</span><span id="page-3" ></span>
<span class="grey"><a href="./rfc5289">RFC 5289</a> TLS ECC New MAC August 2008</span>
These SHALL be as follows:
o For cipher suites ending with _SHA256, the PRF is the TLS PRF
[<a href="./rfc5246" title=""The Transport Layer Security (TLS) Protocol Version 1.2"">RFC5246</a>] with SHA-256 as the hash function. The MAC is HMAC
[<a href="./rfc2104" title=""HMAC: Keyed- Hashing for Message Authentication"">RFC2104</a>] with SHA-256 as the hash function.
o For cipher suites ending with _SHA384, the PRF is the TLS PRF
[<a href="./rfc5246" title=""The Transport Layer Security (TLS) Protocol Version 1.2"">RFC5246</a>] with SHA-384 as the hash function. The MAC is HMAC
[<a href="./rfc2104" title=""HMAC: Keyed- Hashing for Message Authentication"">RFC2104</a>] with SHA-384 as the hash function.
<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>. Galois Counter Mode-Based Cipher Suites</span>
The second eight cipher suites use the same asymmetric algorithms as
those in the previous section but use the new authenticated
encryption modes defined in TLS 1.2 with AES in Galois Counter Mode
(GCM) [<a href="#ref-GCM" title=""Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) for Confidentiality and Authentication"">GCM</a>]:
CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 = {0xC0,0x2B};
CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 = {0xC0,0x2C};
CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 = {0xC0,0x2D};
CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 = {0xC0,0x2E};
CipherSuite TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 = {0xC0,0x2F};
CipherSuite TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 = {0xC0,0x30};
CipherSuite TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 = {0xC0,0x31};
CipherSuite TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384 = {0xC0,0x32};
These cipher suites use authenticated encryption with additional data
algorithms AEAD_AES_128_GCM and AEAD_AES_256_GCM described in
[<a href="./rfc5116" title=""An Interface and Algorithms for Authenticated Encryption"">RFC5116</a>]. GCM is used as described in [<a href="./rfc5288" title=""AES-GCM Cipher Suites for TLS"">RFC5288</a>].
The PRFs SHALL be as follows:
o For cipher suites ending with _SHA256, the PRF is the TLS PRF
[<a href="./rfc5246" title=""The Transport Layer Security (TLS) Protocol Version 1.2"">RFC5246</a>] with SHA-256 as the hash function.
o For cipher suites ending with _SHA384, the PRF is the TLS PRF
[<a href="./rfc5246" title=""The Transport Layer Security (TLS) Protocol Version 1.2"">RFC5246</a>] with SHA-384 as the hash function.
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Security Considerations</span>
The security considerations in <a href="./rfc4346">RFC 4346</a>, <a href="./rfc4492">RFC 4492</a>, and [<a href="./rfc5288" title=""AES-GCM Cipher Suites for TLS"">RFC5288</a>]
apply to this document as well. In addition, as described in
[<a href="./rfc5288" title=""AES-GCM Cipher Suites for TLS"">RFC5288</a>], these cipher suites may only be used with TLS 1.2 or
greater.
<span class="grey">Rescorla Informational [Page 3]</span><span id="page-4" ></span>
<span class="grey"><a href="./rfc5289">RFC 5289</a> TLS ECC New MAC August 2008</span>
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. IANA Considerations</span>
IANA has assigned the following values for these cipher suites:
CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 = {0xC0,0x23};
CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 = {0xC0,0x24};
CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 = {0xC0,0x25};
CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 = {0xC0,0x26};
CipherSuite TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 = {0xC0,0x27};
CipherSuite TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 = {0xC0,0x28};
CipherSuite TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256 = {0xC0,0x29};
CipherSuite TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384 = {0xC0,0x2A};
CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 = {0xC0,0x2B};
CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 = {0xC0,0x2C};
CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 = {0xC0,0x2D};
CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 = {0xC0,0x2E};
CipherSuite TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 = {0xC0,0x2F};
CipherSuite TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 = {0xC0,0x30};
CipherSuite TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 = {0xC0,0x31};
CipherSuite TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384 = {0xC0,0x32};
<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. Acknowledgements</span>
This work was supported by the US Department of Defense.
David McGrew, Pasi Eronen, and Alfred Hoenes provided reviews of this
document.
<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. References</span>
<span class="h3"><a class="selflink" id="section-7.1" href="#section-7.1">7.1</a>. Normative References</span>
[<a id="ref-RFC2104">RFC2104</a>] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", <a href="./rfc2104">RFC 2104</a>,
February 1997.
[<a id="ref-RFC2119">RFC2119</a>] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997.
[<a id="ref-RFC4492">RFC4492</a>] Blake-Wilson, S., Bolyard, N., Gupta, V., Hawk, C., and B.
Moeller, "Elliptic Curve Cryptography (ECC) Cipher Suites
for Transport Layer Security (TLS)", <a href="./rfc4492">RFC 4492</a>, May 2006.
[<a id="ref-RFC5116">RFC5116</a>] McGrew, D., "An Interface and Algorithms for Authenticated
Encryption", <a href="./rfc5116">RFC 5116</a>, January 2008.
[<a id="ref-RFC5246">RFC5246</a>] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", <a href="./rfc5246">RFC 5246</a>, August 2008.
<span class="grey">Rescorla Informational [Page 4]</span><span id="page-5" ></span>
<span class="grey"><a href="./rfc5289">RFC 5289</a> TLS ECC New MAC August 2008</span>
[<a id="ref-RFC5288">RFC5288</a>] Salowey, J., Choudhury, A., and D. McGrew, "AES-GCM Cipher
Suites for TLS", <a href="./rfc5288">RFC 5288</a>, August 2008.
[<a id="ref-AES">AES</a>] National Institute of Standards and Technology,
"Specification for the Advanced Encryption Standard
(AES)", FIPS 197, November 2001.
[<a id="ref-SHS">SHS</a>] National Institute of Standards and Technology, "Secure
Hash Standard", FIPS 180-2, August 2002.
[<a id="ref-CBC">CBC</a>] National Institute of Standards and Technology,
"Recommendation for Block Cipher Modes of Operation -
Methods and Techniques", SP 800-38A, December 2001.
[<a id="ref-GCM">GCM</a>] National Institute of Standards and Technology,
"Recommendation for Block Cipher Modes of Operation:
Galois/Counter Mode (GCM) for Confidentiality and
Authentication", SP 800-38D, November 2007.
<span class="h3"><a class="selflink" id="section-7.2" href="#section-7.2">7.2</a>. Informative References</span>
[<a id="ref-Wang05">Wang05</a>] Wang, X., Yin, Y., and H. Yu, "Finding Collisions in the
Full SHA-1", CRYPTO 2005, August 2005.
Author's Address
Eric Rescorla
RTFM, Inc.
2064 Edgewood Drive
Palo Alto 94303
USA
EMail: [email protected]
<span class="grey">Rescorla Informational [Page 5]</span><span id="page-6" ></span>
<span class="grey"><a href="./rfc5289">RFC 5289</a> TLS ECC New MAC August 2008</span>
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a>, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a> and <a href="https://www.rfc-editor.org/bcp/bcp79">BCP 79</a>.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
<a href="http://www.ietf.org/ipr">http://www.ietf.org/ipr</a>.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
[email protected].
Rescorla Informational [Page 6]
Annotations
Select text to annotate