Network Working Group V. Smyslov Internet-Draft ELVIS-PLUS Intended status: Informational August 27, 2020 Expires: February 28, 2021 Using GOST algorithms in IKEv2 draft-smyslov-ike2-gost-04 Abstract This document defines a set of cryptographic transforms for use in the Internet Key Exchange version 2 (IKEv2) protocol. The transforms are based on Russian cryptographic standard algorithms (GOST). Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on February 28, 2021. Copyright Notice Copyright (c) 2020 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 (https://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 Simplified BSD License. Smyslov Expires February 28, 2021 [Page 1] Internet-Draft GOST algorithms in IKEv2 August 2020 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology and Notation . . . . . . . . . . . . . . . . . . 2 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4. IKE SA Protection . . . . . . . . . . . . . . . . . . . . . . 3 5. Pseudo Random Function . . . . . . . . . . . . . . . . . . . 3 6. Shared Key Calculation . . . . . . . . . . . . . . . . . . . 3 6.1. Recipient Tests . . . . . . . . . . . . . . . . . . . . . 4 7. Authentication . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Hash Functions . . . . . . . . . . . . . . . . . . . . . 4 7.2. ASN.1 Objects . . . . . . . . . . . . . . . . . . . . . . 5 7.2.1. id-tc26-signwithdigest-gost3410-12-256 . . . . . . . 5 7.2.2. id-tc26-signwithdigest-gost3410-12-512 . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . 6 10.2. Informative References . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction This document defines a number of transforms for the Internet Key Exchange version 2 (IKEv2) [RFC7296]. These transforms are based on Russian cryptographic standard algorithms (often called "GOST" algorithms) for hash function, digital signature and key exchange method. Along with transforms defined in [I-D.smyslov-esp-gost], the transforms defined in this specification allow using GOST cryptographic algorithms in IPsec protocols. 2. Terminology and Notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. Overview Russian cryptographic standard (GOST) algorithms are a set of cryptographic algorithms of different types - ciphers, hash functions, digital signatures etc. In particular, Russian cryptographic standard [GOST3412-2015] defines block ciphers "Kuznyechik" (also defined in [RFC7801]) and "Magma" (also defined in [I-D.dolmatov-magma]). Cryptographic standard [GOST3410-2012] defines elliptic curve digital signature algorithm (also defined in Smyslov Expires February 28, 2021 [Page 2] Internet-Draft GOST algorithms in IKEv2 August 2020 [RFC7091]), while [GOST3411-2012] defines two cryptographic hash functions "Stribog", with different output length (also defined in [RFC6986]). The parameters for the elliptic curves used in GOST signature and key exchange algorithms are defined in [RFC7836]. 4. IKE SA Protection Specification [I-D.smyslov-esp-gost] defines two transforms of type 1 (Encryption Algorithm Transform IDs) based on GOST block ciphers that may be used for IKE SA protection: ENCR_KUZNYECHIK_MGM_KTREE (32) based on "Kuznyechik" block cipher and ENCR_MAGMA_MGM_KTREE (33) based on "Magma" block cipher. Since they are AEAD transforms and provide both encryption and authentication, there is no need for new transform type 3 (Integrity Algorithm Transform IDs), because it must not be used with these transforms (or must have a value NONE). 5. Pseudo Random Function This specification defines a new transform of type 2 (Pseudorandom Function Transform IDs) - PRF_HMAC_STRIBOG_512 (). This transform uses PRF HMAC_GOSTR3411_2012_512 defined in Section 4.1.2 of [RFC7836]. The PRF uses GOST R 34.11-2012 ("Stribog") hash- function with 512-bit output defined in [RFC6986][GOST3411-2012] with HMAC [RFC2104] construction. The PRF has a 512-bit block size and a 512-bit output length. 6. Shared Key Calculation This specification defines two new transforms of type 4 (Diffie- Hellman Group Transform IDs): GOST3410_2012_256 () and GOST3410_2012_512 (). These transforms uses Elliptic Curve Diffie-Hellman (ECDH) key exchange algorithm over Twisted Edwards curves. The parameters for these curves are defined in Section A.2 of [RFC7836]. In particular, transform GOST3410_2012_256 uses id-tc26-gost-3410-2012-256-paramSetA parameter set and GOST3410_2012_512 uses id-tc26-gost-3410-2012-512-paramSetC parameter set (both defined in [RFC7836]). Shared secret is computed as follows. The initiator randomly selects its private key d_i from {1,..,q - 1}, where q is the group order and is a parameter of the selected curve. Then a public key Q_i is computed as a point on the curve: Q_i = d_i * G, where G is the generator for the selected curve, and then is sent to the responder. The responder makes the same calculations to get d_r and Q_r and sends Q_r to the initiator. After peers exchange Q_i and Q_R both sides can compute a point on the curve S = ((m / q) * d_i) * Q_r = ((m / q) * d_r) * Q_i, where m is the subgroup order and is a parameter of the selected curve. The shared secret K is an x Smyslov Expires February 28, 2021 [Page 3] Internet-Draft GOST algorithms in IKEv2 August 2020 coordinate of S in a little-endian representation. The size of K is determined by the size of used curve and is either 256 or 512 bit. When GOST public key is transmitted in the KE payload, it MUST be represented as x coordinate immediately followed by y coordinate, each in a little-endian representation. The size of each coordinate is determined by the size of the used curve and is either 256 or 512 bits, so that the size of the Key Exchange Data field in the KE payload is either 64 or 128 octets. 6.1. Recipient Tests Upon receiving peer's public key implementations MUST check that the key is actually a point on the curve, otherwise the exchange fails. Implementations MUST check that the calculated public value S is not an identity element of the curve, in which case the exchange fails. 7. Authentication GOST digital signatures algorithm GOST R 34.10-2012 is defined in [RFC7091][GOST3410-2012]. There are two variants of GOST signature algorithm - one over 256-bit elliptic curve and the other over 512-bit key elliptic curve. When GOST digital signature is used in IKEv2 for authentication purposes, an Authentication Method "Digital Signature" (14) MUST be specified in the AUTH payload. The AlgorithmIdentifier ASN.1 objects for GOST digital signature algorithm are defined in Section 7.2. The signature value, as defined in [RFC7091][GOST3410-2012], consists of two integers r and s. The size of each integer is either 256 bit or 512 bit depending on the used elliptic curve. The content of the Signature Value field in the AUTH payload MUST consist of s immediately followed by r, each in a big-endian representation, so that the size of the field is either 64 or 128 octets. 7.1. Hash Functions GOST digital signatures algorithm uses GOST hash functions GOST R 34.11-2012 ("Stribog") defined in [RFC6986][GOST3411-2012]. There are two "Stribog" hash functions - one with 256-bit output length and the other with 512-bit output length. This specification defines two new values for IKEv2 Hash Algorithms registry: STRIBOG_256 () for GOST hash function with 256-bit output length and STRIBOG_512 () for the 512-bit length output. These values MUST be included in the Smyslov Expires February 28, 2021 [Page 4] Internet-Draft GOST algorithms in IKEv2 August 2020 SIGNATURE_HASH_ALGORITHMS notify if a corresponding GOST digital signature algorithm is supported by the sender. 7.2. ASN.1 Objects This section lists GOST signature algorithm ASN.1 objects in binary form. 7.2.1. id-tc26-signwithdigest-gost3410-12-256 id-tc26-signwithdigest-gost3410-12-256 OBJECT IDENTIFIER ::= { iso(1) member-body(2) ru(643) rosstandart(7) tc26(1) algorithms(1) signwithdigest(3) gost3410-12-256(2) } Parameters are absent. Name = id-tc26-signwithdigest-gost3410-12-256 OID = 1.2.643.7.1.1.3.2 Length = 12 0000: 300a 0608 2a85 0307 0101 0302 7.2.2. id-tc26-signwithdigest-gost3410-12-512 id-tc26-signwithdigest-gost3410-12-512 OBJECT IDENTIFIER ::= { iso(1) member-body(2) ru(643) rosstandart(7) tc26(1) algorithms(1) signwithdigest(3) gost3410-12-512(3) } Parameters are absent. Name = id-tc26-signwithdigest-gost3410-12-256 OID = 1.2.643.7.1.1.3.3 Length = 12 0000: 300a 0608 2a85 0307 0101 0303 8. Security Considerations The security considerations of [RFC7296] apply accordingly. The security of GOST elliptic curves is discussed in [GOST-EC-SECURITY]. The security of "Stribog" hash function is discussed in [STRIBOG-SECURITY]. A second preimage attack on "Stribog" is described in [STRIBOG-PREIMAGE] if message size exceeds 2^259 blocks. This attack is not relevant to how "Stribog" is used in IKEv2. Smyslov Expires February 28, 2021 [Page 5] Internet-Draft GOST algorithms in IKEv2 August 2020 9. IANA Considerations IANA has assigned one Transform ID in the "Transform Type 2 - Pseudorandom Function Transform IDs" registry (where RFCXXXX is this document): Number Name Reference ------------------------------------------------- 9 PRF_HMAC_STRIBOG_512 [RFCXXXX] IANA has assigned two Transform IDs in the "Transform Type 4 - Diffie-Hellman Group Transform IDs" registry (where RFCXXXX is this document): Number Name Recipient Tests Reference --------------------------------------------------------------------- 33 GOST3410_2012_256 [RFCXXXX] Sec. 6.1 [RFCXXXX] 34 GOST3410_2012_512 [RFCXXXX] Sec. 6.1 [RFCXXXX] IANA has assigned two values in the "IKEv2 Hash Algorithms" registry (where RFCXXXX is this document): Number Hash Algorithm Reference ------------------------------------------------- 6 STRIBOG_256 [RFCXXXX] 7 STRIBOG_512 [RFCXXXX] 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC6986] Dolmatov, V., Ed. and A. Degtyarev, "GOST R 34.11-2012: Hash Function", RFC 6986, DOI 10.17487/RFC6986, August 2013, . [RFC7091] Dolmatov, V., Ed. and A. Degtyarev, "GOST R 34.10-2012: Digital Signature Algorithm", RFC 7091, DOI 10.17487/RFC7091, December 2013, . Smyslov Expires February 28, 2021 [Page 6] Internet-Draft GOST algorithms in IKEv2 August 2020 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. Kivinen, "Internet Key Exchange Protocol Version 2 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 2014, . [RFC7836] Smyshlyaev, S., Ed., Alekseev, E., Oshkin, I., Popov, V., Leontiev, S., Podobaev, V., and D. Belyavsky, "Guidelines on the Cryptographic Algorithms to Accompany the Usage of Standards GOST R 34.10-2012 and GOST R 34.11-2012", RFC 7836, DOI 10.17487/RFC7836, March 2016, . [I-D.smyslov-esp-gost] Smyslov, V., "Using GOST ciphers in ESP and IKEv2", draft- smyslov-esp-gost-03 (work in progress), May 2020. 10.2. Informative References [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- Hashing for Message Authentication", RFC 2104, DOI 10.17487/RFC2104, February 1997, . [RFC7801] Dolmatov, V., Ed., "GOST R 34.12-2015: Block Cipher "Kuznyechik"", RFC 7801, DOI 10.17487/RFC7801, March 2016, . [I-D.dolmatov-magma] Dolmatov, V. and D. Eremin-Solenikov, "GOST R 34.12-2015: Block Cipher "Magma"", draft-dolmatov-magma-06 (work in progress), March 2020. [GOST3410-2012] Federal Agency on Technical Regulating and Metrology, "Information technology. Cryptographic data security. Signature and verification processes of [electronic] digital signature", GOST R 34.10-2012, 2012. (In Russian) [GOST3411-2012] Federal Agency on Technical Regulating and Metrology, "Information technology. Cryptographic data security. Hashing function", GOST R 34.11-2012, 2012. (In Russian) Smyslov Expires February 28, 2021 [Page 7] Internet-Draft GOST algorithms in IKEv2 August 2020 [GOST3412-2015] Federal Agency on Technical Regulating and Metrology, "Information technology. Cryptographic data security. Block ciphers", GOST R 34.12-2015, 2015. (In Russian) [GOST-EC-SECURITY] Alekseev, E., Nikolaev, V., and S. Smyshlyaev, "On the security properties of Russian standardized elliptic curves", https://doi.org/10.4213/mvk260, 2018. [STRIBOG-SECURITY] Wang, Z., Yu, H., and X. Wang, "Cryptanalysis of GOST R hash function", https://doi.org/10.1016/j.ipl.2014.07.007, 2014. [STRIBOG-PREIMAGE] Guo, J., Jean, J., Leurent, G., Peyrin, T., and L. Wang, "The Usage of Counter Revisited: Second-Preimage Attack on New Russian Standardized Hash Function", https://eprint.iacr.org/2014/675, 2014. Author's Address Valery Smyslov ELVIS-PLUS PO Box 81 Moscow (Zelenograd) 124460 RU Phone: +7 495 276 0211 Email: svan@elvis.ru Smyslov Expires February 28, 2021 [Page 8]