



Independent Submission                                      B. Makarenko
Request for Comments: 9558         The Technical center of Internet, LLC
Category: Informational                                 V. Dolmatov, Ed.
ISSN: 2070-1721                                     JSC "NPK Kryptonite"
                                                              April 2024


   Use of GOST 2012 Signature Algorithms in DNSKEY and RRSIG Resource
                           Records for DNSSEC

Abstract

   This document describes how to produce digital signatures and hash
   functions using the GOST R 34.10-2012 and GOST R 34.11-2012
   algorithms for DNSKEY, RRSIG, and DS resource records, for use in the
   Domain Name System Security Extensions (DNSSEC).

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not candidates for any level of Internet Standard;
   see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9558.

Copyright Notice

   Copyright (c) 2024 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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

   1.  Introduction
     1.1.  Terminology
   2.  DNSKEY Resource Records
     2.1.  Using a Public Key with Existing Cryptographic Libraries
     2.2.  GOST DNSKEY RR Example
   3.  RRSIG Resource Records
     3.1.  RRSIG RR Example
   4.  DS Resource Records
     4.1.  DS RR Example
   5.  Operational Considerations
     5.1.  Key Sizes
     5.2.  Signature Sizes
     5.3.  Digest Sizes
   6.  Implementation Considerations
   7.  IANA Considerations
   8.  Security Considerations
   9.  References
     9.1.  Normative References
     9.2.  Informative References
   Acknowledgments
   Authors' Addresses

1.  Introduction

   The Domain Name System (DNS) is the global, hierarchically
   distributed database for Internet Naming.  The DNS has been extended
   to use cryptographic keys and digital signatures for the verification
   of the authenticity and integrity of its data.  RFC 4033 [RFC4033],
   RFC 4034 [RFC4034], and RFC 4035 [RFC4035] describe these DNS
   Security Extensions, called DNSSEC.

   RFC 4034 describes how to store DNSKEY and RRSIG resource records and
   specifies a list of cryptographic algorithms to use.  This document
   extends that list with the signature and hash algorithms GOST R
   34.10-2012 ([RFC7091]) and GOST R 34.11-2012 ([RFC6986]), and it
   specifies how to store DNSKEY data and how to produce RRSIG resource
   records with these algorithms.

   GOST R 34.10-2012 and GOST R 34.11-2012 are Russian national
   standards.  Their cryptographic properties haven't been independently
   verified.

   Familiarity with DNSSEC and with GOST signature and hash algorithms
   is assumed in this document.

   Caution:

   This specification is not a standard and does not have IETF community
   consensus.  It makes use of a cryptographic algorithm that is a
   national standard for Russia.  Neither the IETF nor the IRTF has
   analyzed that algorithm for suitability for any given application,
   and it may contain either intended or unintended weaknesses.

1.1.  Terminology

   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.

2.  DNSKEY Resource Records

   The format of the DNSKEY RR can be found in RFC 4034 [RFC4034].

   GOST R 34.10-2012 public keys are stored with the algorithm number
   23.

   According to RFC 7091 [RFC7091], a GOST R 34.10-2012 public key is a
   point on the elliptic curve Q = (x, y).  The wire representation of a
   public key MUST contain 64 octets, where the first 32 octets contain
   the little-endian representation of x and the second 32 octets
   contain the little-endian representation of y.

   As RFC 6986 and RFC 7091 allow two variants of the length of the
   output hash and the signature and many variants of parameters of the
   digital signature, for the purpose of this document we use the
   256-bit variant of the digital signature algorithm, corresponding
   with the 256-bit variant of the digest algorithm.  We select the
   parameters for the digital signature algorithm to be id-tc26-gost-
   3410-2012-256-paramSetA as specified in RFC 7836 [RFC7836]; this
   document refers to it as "parameter set A".

2.1.  Using a Public Key with Existing Cryptographic Libraries

   At the time of this writing, existing GOST-aware cryptographic
   libraries are capable of reading GOST R 34.10-2012 public keys via a
   generic X.509 API if the key is encoded according to RFC 9215
   [RFC9215], Section 4.

   To make this encoding from the wire format of a GOST R 34.10-2012
   public key with the parameters used in this document, prepend the 64
   octets of key data with the following 30-byte sequence:

   0x30 0x5c 0x30 0x17 0x06 0x08 0x2a 0x85
   0x03 0x07 0x01 0x01 0x01 0x01 0x30 0x0b
   0x06 0x09 0x2a 0x85 0x03 0x07 0x01 0x02
   0x01 0x01 0x01 0x03 0x41 0x00

   These bytes provide the following ASN.1 structure suitable for
   parsing by cryptographic toolkits:

     0  92: SEQUENCE {
     2  23:   SEQUENCE {
     4   8:     OBJECT IDENTIFIER '1 2 643 7 1 1 1 1'
    14  11:     SEQUENCE {
    16   9:       OBJECT IDENTIFIER '1 2 643 7 1 2 1 1 1'
          :       }
          :     }
    27  65:   BIT STRING

   The OIDs in the structure above represent a GOST R 34.10-2012 public
   key with a 256-bit private key length and parameter set A.  The
   structure itself represents SubjectPublicKeyInfo field of an X.509
   certificate as defined in RFC 5280 [RFC5280], Section 4.1

2.2.  GOST DNSKEY RR Example

   Given a private key with the following value:

   Private-key-format: v1.2
   Algorithm: 23 (ECC-GOST12)
   Gost12Asn1: MD4CAQAwFwYIKoUDBwEBAQEwCwYJKoUDBwECAQEBBCD/Mw9o6R5lQHJ13
               jz0W+C1tdsS4W7RJn04rk9MGJq3Hg==

   The following DNSKEY RR stores a DNS zone key for example:

   example.  600  IN  DNSKEY  256 3 23 (
               XGiiHlKUJd5fSeAK5O3L4tUNCPxs4pGqum6wKbqjdkqu
               IQ8nOXrilXZ9HcY8b2AETkWrtWHfwvJD4twPPJFQSA==
       ) ;{id = 47355 (zsk), size = 512b}

   The private key here is presented in PrivateKeyInfo ASN.1 structure,
   as described in RFC 5958 [RFC5958], Section 2.

   The public key can be calculated from the private key using algorithm
   described in RFC 7091 [RFC7091].

3.  RRSIG Resource Records

   The value of the signature field in the RRSIG RR follows RFC 7091
   [RFC7091] and is calculated as follows.  The values for the RDATA
   fields that precede the signature data are specified in RFC 4034
   [RFC4034].

   hash = GOSTR3411-2012(data)

   where "data" is the wire format data of the resource record set that
   is signed, as specified in RFC 4034 [RFC4034].

   The signature is calculated from the hash according to GOST R
   34.10-2012, and its wire format is compatible with RFC 7091
   [RFC7091].

3.1.  RRSIG RR Example

   Consider a given RRset consisting of one MX RR to be signed with the
   private key described in Section 2.2 of this document:

   example.  600  IN  MX  10 mail.example.

   Setting the inception date to 2022-10-06 12:32:30 UTC and the
   expiration date to 2022-11-03 12:32:30 UTC, the following signature
   RR will be valid:

   example.  600 IN  RRSIG MX 23 1 600 20221103123230 (
                          20221006123230 47355 example.
                          EuLO0Qpn6zT1pzj9T2H5AWjcgzfmjNiK/vj811bExa0V
                          HMOVD9ma8rpf0B+D+V4Q0CWu1Ayzu+H/SyndnOWGxw==
   )

   The GOST R 34.10-2012 signature algorithm uses random (pseudorandom)
   integer k as described in Section 6.1 of RFC 7091 [RFC7091].  The
   following value for k was used to produce the signature example.

   k = 8BBD0CE7CAF3FC1C2503DF30D13ED5DB75EEC44060FA22FB7E29628407C1E34

   This value for k MUST NOT be used when computing GOST R 34.10-2012
   signatures.  It is provided only so the above signature example can
   be reproduced.  The actual signature value will differ between
   signature calculations.

4.  DS Resource Records

   The GOST R 34.11-2012 digest algorithm is denoted in DS RRs by the
   digest type 5.  The wire format of a digest value is compatible with
   RFC 6986 [RFC6986].

4.1.  DS RR Example

   For Key Signing Key (KSK):

   example.  IN  DNSKEY  257 3 23 (
                          p8Req8DLJOfPymO5vExuK4gCcihF5N1YL7veCJ47av+w
                          h/qs9yJpD064k02rYUHfWnr7IjvJlbn3Z0sTZe9GRQ==
                          ) ;{id = 29468 (ksk), size = 512b}

   The DS RR will be:

   example.  IN  DS  29468 23 5 (
                         6033725b0ccfc05d1e9d844d49c6cf89
                         0b13d5eac9439189947d5db6c8d1c1ec
                         )

5.  Operational Considerations

5.1.  Key Sizes

   The key size of GOST R 34.10-2012 public keys conforming to this
   specification MUST be 512 bits according to RFC 7091 [RFC7091].

5.2.  Signature Sizes

   The size of a GOST R 34.10-2012 signature conforming to this
   specification MUST be 512 bits according to RFC 7091 [RFC7091].

5.3.  Digest Sizes

   The size of a GOST R 34.11-2012 digest conforming to this
   specification MUST be 256 bits according to RFC 6986 [RFC6986].

6.  Implementation Considerations

   The support of this cryptographic suite in DNSSEC-aware systems is
   OPTIONAL.  According to RFC 6840 [RFC6840], Section 5.2, systems that
   do not support these algorithms MUST ignore the RRSIG, DNSKEY, and DS
   resource records associated with the GOST R 34.10-2012 digital
   signature algorithm.

7.  IANA Considerations

   The following entry has been added to the IANA registry for "DNS
   Security Algorithm Numbers":

   +========+=============+============+=========+========+===========+
   | Number | Description | Mnemonic   | Zone    | Trans. | Reference |
   |        |             |            | Signing | Sec.   |           |
   +========+=============+============+=========+========+===========+
   | 23     | GOST R      | ECC-GOST12 | Y       | *      | RFC 9558  |
   |        | 34.10-2012  |            |         |        |           |
   +--------+-------------+------------+---------+--------+-----------+

                                 Table 1

   The following entry has been added to the IANA registry for "Digest
   Algorithms" in the "Delegation Signer (DS) Resource Record (RR) Type
   Digest Algorithms" registry group:

           +=======+===================+==========+===========+
           | Value | Description       | Status   | Reference |
           +=======+===================+==========+===========+
           | 5     | GOST R 34.11-2012 | OPTIONAL | RFC 9558  |
           +-------+-------------------+----------+-----------+

                                 Table 2

8.  Security Considerations

   It is recommended to use a dual KSK algorithm signed zone until GOST-
   aware DNSSEC software becomes more widespread, unless GOST-only
   cryptography is to be used.  Otherwise, GOST-signed zones may be
   considered unsigned by the DNSSEC software currently in use.

   Like all algorithms, it is possible that a significant flaw could be
   discovered with GOST R 34.11-2012.  In that case, deployments should
   roll over to another algorithm.  See RFC 7583 [RFC7583] on the timing
   of such changes.

9.  References

9.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3110]  Eastlake 3rd, D., "RSA/SHA-1 SIGs and RSA KEYs in the
              Domain Name System (DNS)", RFC 3110, DOI 10.17487/RFC3110,
              May 2001, <https://www.rfc-editor.org/info/rfc3110>.

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements",
              RFC 4033, DOI 10.17487/RFC4033, March 2005,
              <https://www.rfc-editor.org/info/rfc4033>.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, DOI 10.17487/RFC4034, March 2005,
              <https://www.rfc-editor.org/info/rfc4034>.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
              <https://www.rfc-editor.org/info/rfc4035>.

   [RFC6840]  Weiler, S., Ed. and D. Blacka, Ed., "Clarifications and
              Implementation Notes for DNS Security (DNSSEC)", RFC 6840,
              DOI 10.17487/RFC6840, February 2013,
              <https://www.rfc-editor.org/info/rfc6840>.

   [RFC6986]  Dolmatov, V., Ed. and A. Degtyarev, "GOST R 34.11-2012:
              Hash Function", RFC 6986, DOI 10.17487/RFC6986, August
              2013, <https://www.rfc-editor.org/info/rfc6986>.

   [RFC7091]  Dolmatov, V., Ed. and A. Degtyarev, "GOST R 34.10-2012:
              Digital Signature Algorithm", RFC 7091,
              DOI 10.17487/RFC7091, December 2013,
              <https://www.rfc-editor.org/info/rfc7091>.

   [RFC7583]  Morris, S., Ihren, J., Dickinson, J., and W. Mekking,
              "DNSSEC Key Rollover Timing Considerations", RFC 7583,
              DOI 10.17487/RFC7583, October 2015,
              <https://www.rfc-editor.org/info/rfc7583>.

   [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,
              <https://www.rfc-editor.org/info/rfc7836>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

9.2.  Informative References

   [RFC4509]  Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer
              (DS) Resource Records (RRs)", RFC 4509,
              DOI 10.17487/RFC4509, May 2006,
              <https://www.rfc-editor.org/info/rfc4509>.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
              <https://www.rfc-editor.org/info/rfc5280>.

   [RFC5933]  Dolmatov, V., Ed., Chuprina, A., and I. Ustinov, "Use of
              GOST Signature Algorithms in DNSKEY and RRSIG Resource
              Records for DNSSEC", RFC 5933, DOI 10.17487/RFC5933, July
              2010, <https://www.rfc-editor.org/info/rfc5933>.

   [RFC5958]  Turner, S., "Asymmetric Key Packages", RFC 5958,
              DOI 10.17487/RFC5958, August 2010,
              <https://www.rfc-editor.org/info/rfc5958>.

   [RFC9215]  Baryshkov, D., Ed., Nikolaev, V., and A. Chelpanov, "Using
              GOST R 34.10-2012 and GOST R 34.11-2012 Algorithms with
              the Internet X.509 Public Key Infrastructure", RFC 9215,
              DOI 10.17487/RFC9215, March 2022,
              <https://www.rfc-editor.org/info/rfc9215>.

Acknowledgments

   This document is a minor extension to RFC 4034 [RFC4034].  Also, we
   tried to follow the documents RFC 3110 [RFC3110], RFC 4509 [RFC4509],
   and RFC 5933 [RFC5933] for consistency.  The authors of and
   contributors to these documents are gratefully acknowledged for their
   hard work.

   The following people provided additional feedback, text, and valuable
   assistance: Alexander Venedyukhin, Michael StJohns, Valery Smyslov,
   Tim Wicinski, and Stéphane Bortzmeyer.

Authors' Addresses

   Boris Makarenko
   The Technical center of Internet, LLC
   8 marta St., 1, Bldg. 12
   Moscow
   127083
   Russian Federation
   Email: bmakarenko@tcinet.ru


   Vasily Dolmatov (editor)
   JSC "NPK Kryptonite"
   Spartakovskaya Sq., 14, Bldg. 2
   Moscow
   105082
   Russian Federation
   Email: vdolmatov@gmail.com
