Network Working Group A. Kato Internet-Draft S. Kanno Intended status: Standards Track NTT Software Corporation Expires: June 24, 2010 M. Kanda NTT T. Iwata Nagoya University December 21, 2009 The Camellia-CMAC-96 and Camellia-CMAC-PRF-128 Algorithms and Its Use with IPsec draft-kato-ipsec-camellia-cmac96and128-05 Abstract This memo specifies two new algorithms for IPsec. One is the usage of Cipher-based Message Authentication Code (CMAC) with the Camellia block cipher as an authentication mechanism in the IPsec Encapsulating Security Payload and Authentication Header protocols. This algorithm is called Camellia-CMAC-96. The other algorithm is a pseudo-random function (PRF) based on CMAC with the Camellia block cipher for the Internet Key Exchange, version 2. This algorithm is called Camellia-CMAC-PRF-128. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on June 24, 2010. Kato, et al. Expires June 24, 2010 [Page 1] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Kato, et al. Expires June 24, 2010 [Page 2] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Camellia-CMAC . . . . . . . . . . . . . . . . . . . . . . . . 7 4. Camellia-CMAC-96 . . . . . . . . . . . . . . . . . . . . . . . 8 5. Camellia-CMAC-PRF-128 . . . . . . . . . . . . . . . . . . . . 9 6. Test Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.1. Camellia-CMAC-96 . . . . . . . . . . . . . . . . . . . . . 11 6.2. Camellia-CMAC-PRF-128 . . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 10.1. Normative . . . . . . . . . . . . . . . . . . . . . . . . 18 10.2. Informative . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 Kato, et al. Expires June 24, 2010 [Page 3] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 1. Introduction The NIST specification [1] for the CMAC (Cipher-based Message Authentication Code) mode of operation for a block cipher describes a method to use the Advanced Encryption Standard (AES) as a Message Authentication Code (MAC) that has a 128-bit output length. The Camellia block cipher has the same external interface as the AES. This memo specifies two new algorithms for IPsec that replace AES by Camellia in already specified applications of CMAC for IPsec [8] and [9]. One is the usage of CMAC mode with Camellia [2] as the underlying block cipher as an authentication mechanism in the IPsec Encapsulating Security Payload (ESP) [5] and Authentication Header (AH) [4] protocols. This algorithm is called Camellia-CMAC-96. The 128-bit CMAC output is also useful as a long-lived Pseudo-Random Function (PRF). Thus, the other algorithm is a PRF based on CMAC with the Camellia block cipher for version 2 of the Internet Key Exchange (IKEv2) [6] that supports fixed and variable key sizes for the Key Derivation Function (KDF) and authentication, respectively. This algorithm is called Camellia-CMAC-PRF-128. The Camellia algorithm and its properties are described in [2]. This document does not cover implementation details of CMAC. Those details can be found in [1]. For further information on IKE, AH and ESP, refer to [3], [4], [5], and [6]. Kato, et al. Expires June 24, 2010 [Page 4] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 2. Definitions CBC Cipher Block Chaining mode of operation for a block cipher, providing a block cipher for arbitrary message sizes. MAC Message Authentication Code. A bit string of a fixed length, computed by the MAC generation algorithm, that is used to establish the authority and, hence, the integrity of a message. CMAC A MAC algorithm based on a symmetric key block cipher in CBC mode, as specified in [1]. Key (K) 128-bit (16-octet) key for the Camellia block cipher. Denoted by K. Variable-length Key (VK) Variable-length key for Camellia-CMAC-PRF-128, denoted by VK. Message (M) Message to be authenticated. Denoted by M. Length (len) The length of message M in octets. Denoted by len. The minimum value is 0. The maximum value is not specified in this document. VKlen The length of VK in octets. truncate(T,l) Truncate T (MAC) in most-significant-bit-first (MSB-first) order to a length of l octets. T The output of Camellia-CMAC. Camellia-CMAC CMAC generation function based on the Camellia block cipher with 128-bit key. Kato, et al. Expires June 24, 2010 [Page 5] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 Camellia-CMAC-96 IPsec AH and ESP MAC generation function based on Camellia- CMAC, which truncates the 128-bit CMAC output to its 96 most-significant bits. Camellia-CMAC-PRF-128 IPsec AH and ESP PRF based on Camellia-CMAC, which removes the 128-bit key length restriction. SKEYSEED Seed of shared key calculated from the nonces exchanged during the IKE_SA_INIT exchange and the Diffie-Hellman shared secret in the IKEv2 specification [6]. Kato, et al. Expires June 24, 2010 [Page 6] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 3. Camellia-CMAC The National Institute of Standards and Technology (NIST) has specified the Cipher-based Message Authentication Code (CMAC) [1]. CMAC is a keyed hash function that is based on a symmetric key block cipher, such as the Advanced Encryption Standard [10]. The CMAC algorithm provides a framework for inserting various block cipher algorithms. Camellia-CMAC uses the Camellia block cipher [2] as a building block in CMAC [1]. To generate a MAC, Camellia-CMAC(K, M, len) takes a secret key 'K', a message of variable length 'M', and the length of the message in octets 'len' as inputs and returns a fixed-length bit string. In this specification, Camellia-CMAC is always used with 128-bit length key. Kato, et al. Expires June 24, 2010 [Page 7] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 4. Camellia-CMAC-96 For IPsec message authentication in AH and ESP, Camellia-CMAC is used in its truncated form denoted as Camellia-CMAC-96 -- Camellia-CMAC with its output truncated to 96 bits. Its output is a 96-bit MAC that meets the default authenticator length as specified in [4]. The result of truncation is taken in MSB-first order. Figure 1 describes Camellia-CMAC-96 algorithm: In step 1, Camellia-CMAC with key K is applied to the message M of length len octets. In step 2, the output of step 1 is truncated to its first 12 octets, and the result (TT) is returned. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + Algorithm Camellia-CMAC-96 + +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + + + Input : K (128-bit Key) + + : M (message to be authenticated) + + : len (length of message in octets) + + Output : Truncated T (truncated output to length 12 octets) + + + +-------------------------------------------------------------------+ + + + Step 1. T := Camellia-CMAC (K,M,len); + + Step 2. TT := truncate (T, 12); + + return TT; + +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Figure 1: Algorithm Camellia-CMAC-96 Kato, et al. Expires June 24, 2010 [Page 8] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 5. Camellia-CMAC-PRF-128 The Camellia-CMAC-PRF-128 algorithm is identical to Camellia-CMAC except that the 128-bit key length restriction is removed. IKEv2 [6] uses PRFs for multiple purposes, most notably for generating keying material and authentication of the IKE_SA. When using Camellia-CMAC-PRF-128 as the PRF described in [6], Camellia-CMAC-PRF-128 is considered to admit a variable key length in all places, and the amount of keying material generated when new keys are generated is 128 bits (i.e., preferred key length when generating keying material of SK_d, SK_pi, and SK_pr is 128 bits). When generating SKEYSEED the full of Ni and Nr are used as key for the PRF. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + Camellia-CMAC-PRF-128 + +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + + + Input : VK (Variable-length key) + + : M (Message, i.e., the input data of the PRF) + + : VKlen (length of VK in octets) + + : len (length of M in octets) + + Output : PRV (128-bit Pseudo-Random Variable) + + + +-------------------------------------------------------------------+ + Variable: K (128-bit key for Camellia-CMAC) + + + + Step 1. If VKlen is equal to 16 + + Step 1a. then + + K := VK; + + Step 1b. else + + K := Camellia-CMAC(0^128, VK, VKlen); + + Step 2. PRV := Camellia-CMAC(K, M, len); + + return PRV; + + + +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Figure 2: Algorithm Camellia-CMAC-PRF-128 In step 1, the 128-bit key, K, for Camellia-CMAC is derived as follows: Kato, et al. Expires June 24, 2010 [Page 9] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 o If the key VK is exactly 128 bits, then we use it as-is (step 1a). o If it is longer or shorter than 128 bits, then we derive the key K by applying the Camellia-CMAC algorithm using the 128-bit all-zero string as the key and VK as the input message (step 1b). In step 2, we apply the Camellia-CMAC algorithm using K as the key and M as the input message. The output of this algorithm is returned. Kato, et al. Expires June 24, 2010 [Page 10] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 6. Test Cases 6.1. Camellia-CMAC-96 This section contains four test cases, which can be used to confirm that an implementation has correctly implemented Camellia-CMAC-96. ---------------- K 2b7e1516 28aed2a6 abf71588 09cf4f3c Mlen = 0 M T ba925782 aaa1f5d9 a00f8964 ---------------- K 2b7e1516 28aed2a6 abf71588 09cf4f3c Mlen = 16 M 6bc1bee2 2e409f96 e93d7e11 7393172a T 6d962854 a3b9fda5 6d7d45a9 ---------------- K 2b7e1516 28aed2a6 abf71588 09cf4f3c Mlen = 40 M 6bc1bee2 2e409f96 e93d7e11 7393172a ae2d8a57 1e03ac9c 9eb76fac 45af8e51 30c81c46 a35ce411 T 5c18d119 ccd67661 44ac1866 ---------------- K 2b7e1516 28aed2a6 abf71588 09cf4f3c Mlen = 64 M 6bc1bee2 2e409f96 e93d7e11 7393172a ae2d8a57 1e03ac9c 9eb76fac 45af8e51 30c81c46 a35ce411 e5fbc119 1a0a52ef f69f2445 df4f9b17 ad2b417b e66c3710 T c2699a6e ba55ce9d 939a8a4e 6.2. Camellia-CMAC-PRF-128 This section contains twelve test cases, which can be used to confirm that an implementation has correctly implemented Camellia-CMAC-PRF- 128. The first four test cases use 128 bit VK; the next four test cases use 192 bit VK; and the last four test cases use 256 bit VK. Kato, et al. Expires June 24, 2010 [Page 11] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 VKlen = 16 ---------------- VK 2b7e1516 28aed2a6 abf71588 09cf4f3c Mlen = 0 M T ba925782 aaa1f5d9 a00f8964 8094fc71 ---------------- VK 2b7e1516 28aed2a6 abf71588 09cf4f3c Mlen = 16 M 6bc1bee2 2e409f96 e93d7e11 7393172a T 6d962854 a3b9fda5 6d7d45a9 5ee17993 ---------------- VK 2b7e1516 28aed2a6 abf71588 09cf4f3c Mlen = 40 M 6bc1bee2 2e409f96 e93d7e11 7393172a ae2d8a57 1e03ac9c 9eb76fac 45af8e51 30c81c46 a35ce411 T 5c18d119 ccd67661 44ac1866 131d9f22 ---------------- VK 2b7e1516 28aed2a6 abf71588 09cf4f3c Mlen = 64 M 6bc1bee2 2e409f96 e93d7e11 7393172a ae2d8a57 1e03ac9c 9eb76fac 45af8e51 30c81c46 a35ce411 e5fbc119 1a0a52ef f69f2445 df4f9b17 ad2b417b e66c3710 T c2699a6e ba55ce9d 939a8a4e 19466ee9 ------------------------------------------------------------ VKlen = 24 ---------------- VK 8e73b0f7 da0e6452 c810f32b 809079e5 62f8ead2 522c6b7b K abddaa68 e8b9f0af 2fb4db53 41cf1d91 Mlen = 0 M Kato, et al. Expires June 24, 2010 [Page 12] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 T f4739892 c70bd23e 891f66c0 5fefbf27 ---------------- VK 8e73b0f7 da0e6452 c810f32b 809079e5 62f8ead2 522c6b7b K abddaa68 e8b9f0af 2fb4db53 41cf1d91 Mlen = 16 M 6bc1bee2 2e409f96 e93d7e11 7393172a T 60a33814 53babaed 1a11dfd3 d24c1410 ---------------- VK 8e73b0f7 da0e6452 c810f32b 809079e5 62f8ead2 522c6b7b K abddaa68 e8b9f0af 2fb4db53 41cf1d91 Mlen = 40 M 6bc1bee2 2e409f96 e93d7e11 7393172a ae2d8a57 1e03ac9c 9eb76fac 45af8e51 30c81c46 a35ce411 T 42b9d47f 4f58bc29 85b6f82c 23b121cb ---------------- VK 8e73b0f7 da0e6452 c810f32b 809079e5 62f8ead2 522c6b7b K abddaa68 e8b9f0af 2fb4db53 41cf1d91 Mlen = 64 M 6bc1bee2 2e409f96 e93d7e11 7393172a ae2d8a57 1e03ac9c 9eb76fac 45af8e51 30c81c46 a35ce411 e5fbc119 1a0a52ef f69f2445 df4f9b17 ad2b417b e66c3710 T d078729f dcae9abc ff1ea4d6 18ed4501 ------------------------------------------------------------ VKlen = 32 ---------------- VK 603deb10 15ca71be 2b73aef0 857d7781 1f352c07 3b6108d7 2d9810a3 0914dff4 K b5aeeae9 2c23bed7 167af194 2e831597 Mlen = 0 M T c96d7d40 d4aaab78 ac906b91 c82bd690 Kato, et al. Expires June 24, 2010 [Page 13] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 ---------------- VK 603deb10 15ca71be 2b73aef0 857d7781 1f352c07 3b6108d7 2d9810a3 0914dff4 K b5aeeae9 2c23bed7 167af194 2e831597 Mlen = 16 M 6bc1bee2 2e409f96 e93d7e11 7393172a T 104de4b9 0da6baf1 fa73945b e614f032 ---------------- VK 603deb10 15ca71be 2b73aef0 857d7781 1f352c07 3b6108d7 2d9810a3 0914dff4 K b5aeeae9 2c23bed7 167af194 2e831597 Mlen = 40 M 6bc1bee2 2e409f96 e93d7e11 7393172a ae2d8a57 1e03ac9c 9eb76fac 45af8e51 30c81c46 a35ce411 T 2d3684e9 1cb1b303 a7db8648 f25ee16c ---------------- VK 603deb10 15ca71be 2b73aef0 857d7781 1f352c07 3b6108d7 2d9810a3 0914dff4 K b5aeeae9 2c23bed7 167af194 2e831597 Mlen = 64 M 6bc1bee2 2e409f96 e93d7e11 7393172a ae2d8a57 1e03ac9c 9eb76fac 45af8e51 30c81c46 a35ce411 e5fbc119 1a0a52ef f69f2445 df4f9b17 ad2b417b e66c3710 T d6b0f1b7 dda2b62a eca6d51d da63fdda Kato, et al. Expires June 24, 2010 [Page 14] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 7. Security Considerations The security provided by Camellia-CMAC-96 and Camellia-CMAC-PRF-128 is built on the strong cryptographic algorithm Camellia and CMAC. At the time of this writing, there are no known practical cryptographic attacks against Camellia or CMAC. However, as is true with any cryptographic algorithm, part of its strength lies in the secret key, K, and the correctness of the implementation in all of the participating systems. If the secret key is compromised or inappropriately shared, it guarantees neither authentication nor message integrity at all. The secret key shall be generated in a way that meets the pseudo randomness requirement of RFC 4086 [7] and should be kept safe. If and only if Camellia-CMAC-96 and Camellia-CMAC-PRF-128 are used properly it provides the authentication and integrity that meet the best current practice of message authentication. Kato, et al. Expires June 24, 2010 [Page 15] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 8. IANA Considerations The IANA has allocated value for IKEv2 Transform Type 3 (Integrity Algorithm) to the AUTH_CAMELLIA_CMAC_96 algorithm, and has allocated a value of for IKEv2 Transform Type 2 (Pseudo-Random Function) to the PRF_CAMELLIA128_CMAC algorithm. Kato, et al. Expires June 24, 2010 [Page 16] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 9. Acknowledgements We thank Tim Polk and Tero Kivinen for their initial review of this document. Special thanks to Alfred Hoenes for several very detailed reviews and suggestions. Kato, et al. Expires June 24, 2010 [Page 17] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 10. References 10.1. Normative [1] National Institute of Standards and Technology, "Recommendation for Block Cipher Modes of Operation:The CMAC Mode for Authentication", Special Publication 800-38B, May 2005. [2] Matsui, M., Nakajima, J., and S. Moriai, "A Description of the Camellia Encryption Algorithm", RFC 3713, April 2004. 10.2. Informative [3] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, December 2005. [4] Kent, S., "IP Authentication Header", RFC 4302, December 2005. [5] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 4303, December 2005. [6] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, "Internet Key Exchange Protocol: IKEv2", draft-ietf-ipsecme-ikev2bis-06 (work in progress), December 2009. [7] Eastlake, D., Schiller, J., and S. Crocker, "Randomness Requirements for Security", BCP 106, RFC 4086, June 2005. [8] Song, JH., Poovendran, R., and J. Lee, "The AES-CMAC-96 Algorithm and Its Use with IPsec", RFC 4494, June 2006. [9] Gustin, J. and A. Goyens, "A Uniform Resource Name (URN) Namespace for SWIFT Financial Messaging", RFC 3615, September 2003. [10] National Institute of Standards and Technology, "Advanced Encryption Standard (AES)", FIPS PUB 197, November 2001, . Kato, et al. Expires June 24, 2010 [Page 18] Internet-Draft The Camellia CMAC-96 and CMAC-PRF-128 December 2009 Authors' Addresses Akihiro Kato NTT Software Corporation Phone: +81-45-212-9803 Fax: +81-45-212-9800 Email: kato.akihiro@po.ntts.co.jp Satoru Kanno NTT Software Corporation Phone: +81-45-212-9803 Fax: +81-45-212-9800 Email: kanno.satoru@po.ntts.co.jp Masayuki Kanda NTT Phone: +81-422-59-3456 Fax: +81-422-59-4015 Email: kanda.masayuki@lab.ntt.co.jp Tetsu Iwata Nagoya University Email: iwata@cse.nagoya-u.ac.jp Kato, et al. Expires June 24, 2010 [Page 19]