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

The Domain Name System (DNS) is the global hierarchical 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 , RFC 4034 , and RFC 4035 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 () and GOST R 34.11-2012 (), and specifies how to store DNSKEY data and how to produce RRSIG resource records with these algorithms. This document obsoletes RFC5933 . This document also marks the DNS Security Algorithm GOST R 34.10-2001 as obsolete. Familiarity with DNSSEC and with GOST signature and hash algorithms is assumed in this document.

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 when, and only when, they appear in all capitals, as shown here.

The format of the DNSKEY RR can be found in RFC 4034 . GOST R 34.10-2012 public keys are stored with the algorithm number TBA1. According to RFC 7091 , a 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 allows 2 variants of length of the output hash and signature and many variants of parameters of the digital signature, for the purpose of this document we use 256-bit variant of the digital signature algorithm, corresponding 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 in RFC 7836 .

At the time of this writing, existing GOST-aware cryptographic libraries are capable of reading GOST public keys via a generic X509 API if the key is encoded according to RFC 7091 , Section 2.3.2. To make this encoding from the wire format of a GOST public key with the parameters used in this document, prepend the 64 octets of key data with the following 32-byte sequence: 0x30 0x5e 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 0x43 0x00 0x04 0x40

Given a private key with the following value (the value of the Gost12Asn1 field is split here into two lines to simplify reading; in the private key file, it must be in one line):

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

where "data" is the wire format data of the resource record set that is signed, as specified in RFC 4034 . The signature is calculated from the hash according to the GOST R 34.10-2012 standard, and its wire format is compatible with RFC 7091 .

With the private key from this document, consisting of one MX record: example. 600 IN MX 10 mail.example. Setting the inception date to 2020-01-04 17:25:26 UTC and the expiration date to 2020-02-01 17:25:26 UTC, the following signature RR will be valid:

Note: The ECC-GOST12 signature algorithm uses random data, so the actual computed signature value will differ between signature calculations.

The GOST R 34.11-2012 digest algorithm is denoted in DS RRs by the digest type TBA2. The wire format of a digest value is compatible with RFC 6986 .

For Key Signing Key (KSK):

The DS RR will be:

The key size of GOST public keys conforming to this specification MUST be 512 bits.

The size of a GOST signature conforming to this specification MUST be 512 bits.

The size of a GOST digest conforming to this specification MUST be 256 bits.

DNSSEC-aware implementations MAY be able to support RRSIG and DNSKEY resource records created with the GOST algorithms as defined in this document.

This document updates RFC8624 . The paragraph describing the state of GOST algorithms in section 3.1 of RFC 8624 currently says: ECC-GOST (GOST R 34.10-2001) has been superseded by GOST R 34.10-2012 in [RFC7091]. GOST R 34.10-2012 hasn't been standardized for use in DNSSEC. That paragraph is now replaced with the following: ECC-GOST (GOST R 34.10-2001) has been superseded by GOST R 34.10-2012 in [RFC7091]. GOST R 34.10-2012 has been standardized for use in DNSSEC in RFC TBC.

Currently, the cryptographic resistance of the GOST R 34.10-2012 digital signature algorithm is estimated as 2**128 operations of multiple elliptic curve point computations on prime modulus of order 2**256. Currently, the cryptographic collision resistance of the GOST R 34.11-2012 hash algorithm is estimated as 2**128 operations of computations of a step hash function.

This document updates the IANA registry "DNS Security Algorithm Numbers". The following entries have been added to the registry:

The entry for the Algorithm "GOST R 34.10-2001", number 12 should be updated as such: Description field should be changed to "GOST R 34.10-2001 (deprecated, see TBA1" and Zone Signing field should be changed to "N". This document updates the RFC IANA registry "Delegation Signer (DS) Resource Record (RR) Type Digest Algorithms" by adding an entry for the GOST R 34.11-2012 algorithm:

The entry for Value 3, GOST R 34.11-94 should be updated to have its Status changed to '-'. This paragraph shoud be removed before the publication of RFC: For the purpose of example computations, the following values were used: TBA1 = 23, TBA2 = 5.

This document is a minor extension to RFC 4034 . Also, we tried to follow the documents RFC 3110 , RFC 4509 , and RFC 5933 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, Valery Smyslov, Tim Wicinski.