S/MIME WG Sean Turner, IECA Intended Status: Standard Track Expires:~~October 29, 2008~~March 10, 2009Using SHA2 Algorithms with Cryptographic Message Syntax~~draft-ietf-smime-sha2-05.txt~~draft-ietf-smime-sha2-06.txtStatus of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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~~October 29,~~March 10,2008. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract This document describes the conventions for using the Secure Hash Algorithm (SHA) message digest algorithms (SHA-224, SHA-256, SHA-384, SHA-512) with the Cryptographic Message Syntax (CMS). It also describes the conventions for using these algorithms with CMS and the Digital Signature Algorithm (DSA), Rivest Shamir Adleman (RSA), and Elliptic Curve DSA (ECDSA) signature algorithms. Conventions used in this document 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 [RFC2119]. Table of Contents 1. Introduction...................................................2 2. Message Digest Algorithms......................................3 2.1. SHA-224...................................................4 2.2. SHA-256...................................................4 2.3. SHA-384...................................................4 2.4. SHA-512...................................................4 3. Signature Algorithms...........................................5 3.1. DSA.......................................................5 3.2. RSA.......................................................6 3.3. ECDSA.....................................................6 4. Security Considerations........................................7 5. IANA Considerations............................................7 6. References.....................................................7 6.1. Normative References......................................7 6.2. Informative References....................................8 1. Introduction This document specifies the algorithm identifiers and specifies parameters for the message digest algorithms SHA-224, SHA-256, SHA- 384, and SHA-512 for use with the Cryptographic Message Syntax (CMS) [RFC3852]. The message digest algorithms are defined in [SHS] and reference code is provided in [RFC4634]. This document also specifies the algorithm identifiers and parameters for use of SHA-224, SHA-256, SHA-384, and SHA-512 with DSA [DSS], RSA [RFC2313], and ECDSA [X9.62]. This document does not define new identifiers; they are taken from [RFC3874], [RFC4055], [ECCADD], and [RFC3278]. Additionally, the parameters follow the conventions specified therein. Therefore, there is no Abstract Syntax Notation One (ASN.1) module included in this document. Note that [RFC4231] specifies the conventions for the message authentication code (MAC) algorithms: HMAC with SHA-224, HMAC with SHA-256, HMAC with SHA-384, and HMAC with SHA-512. In CMS, the various algorithm identifiers use the AlgorithmIdentifier syntax, which is included here for convenience: AlgorithmIdentifier ::= SEQUENCE { algorithm OBJECT IDENTIFIER, parameters ANY DEFINED BY algorithm OPTIONAL } 2. Message Digest Algorithms Digest algorithm identifiers are located in the SignedData digestAlgorithms field, the SignerInfo digestAlgorithm field, the DigestedData digestAlgorithm field, and the AuthenticatedData digestAlgorithm field. Digest values are located in the DigestedData digest field and the Message Digest authenticated attribute. In addition, digest values are input to signature algorithms. The digest algorithm identifiers use the AlgorithmIdentifier syntax elaborated upon in Section 1. The algorithm field is discussed in Sections 2.1-2.4 for each message digest algorithm. There are two possible encodings for the SHA AlgorithmIdentifier parameters field. The two alternatives arise from the fact that when the 1988 syntax for AlgorithmIdentifier was translated into the 1997 syntax, the OPTIONAL associated with the AlgorithmIdentifier parameters got lost. Later the OPTIONAL was recovered via a defect report, but by then many people thought that algorithm parameters were mandatory. Because of this history some implementations encode parameters as a NULL element and others omit them entirely. The correct encoding is to omit the parameters field; however, implementations MUST also handle a SHA AlgorithmIdentifier parameters field which contains a NULL. The AlgorithmIdentifier parameters field is OPTIONAL. If present, the parameters field MUST contain a NULL. Implementations MUST accept SHA2 AlgorithmIdentifiers with absent parameters. Implementations MUST accept SHA2 AlgorithmIdentifiers with NULL parameters. Implementations SHOULD generate SHA2 AlgorithmIdentifiers with absent parameters. 2.1. SHA-224 The SHA-224 message digest algorithm is defined in [SHS]. The algorithm identifier for SHA-224 is: id-sha224 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) csor(3) nistalgorithm(4) hashalgs(2) 4 } The parameters are as specified in Section 2. 2.2. SHA-256 The SHA-256 message digest algorithm is defined in [SHS]. The algorithm identifier for SHA-256 is: id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) csor(3) nistalgorithm(4) hashalgs(2) 1 } The parameters are as specified in Section 2. 2.3. SHA-384 The SHA-384 message digest algorithm is defined in [SHS]. The algorithm identifier for SHA-384 is: id-sha384 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) csor(3) nistalgorithm(4) hashalgs(2) 2 } The parameters are as specified in Section 2. 2.4. SHA-512 The SHA-512 message digest algorithm is defined in [SHS]. The algorithm identifier for SHA-512 is: id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) csor(3) nistalgorithm(4) hashalgs(2) 3 } The parameters are as specified in Section 2. 3. Signature Algorithms This section specifies the conventions employed by CMS implementations that support DSA, RSA, and ECDSA with SHA2 algorithms. Signature algorithm identifiers are located in the SignerInfo signatureAlgorithm field of SignedData. Also, signature algorithm identifiers are located in the SignerInfo signatureAlgorithm field of countersignature attributes. Signature values are located in the SignerInfo signature field of SignedData. Also, signature values are located in the SignerInfo signature field of countersignature attributes. 3.1. DSA [RFC3370] section 3.1 specifies the conventions for DSA with SHA1 public key algorithm identifiers, parameters, public keys, and signature values. DSA with SHA2 algorithms uses the same conventions for these public key algorithm identifiers, parameters, public keys, and signature values. DSA MAY be used with SHA-224 and SHA-256. DSA has not been specified with SHA-384 and SHA-512. SHA-384 and SHA-512 are not supported because the maximum bit length of p (specified as L) is 3072 for DSA. For consistent cryptographic strength, SHA-384 would be used with DSA where L is 7068, and SHA-512 would be used with DSA where L is 15360. The algorithm identifier for DSA with SHA-224 signature values is: id-dsa-with-sha224 OBJECT IDENTIFIER ::= { joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101) csor(3) algorithms(4) id-dsa-with-sha2(3) 1 } The algorithm identifier for DSA with SHA-256 signature values is: id-dsa-with-sha256 OBJECT IDENTIFIER ::= { joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101) csor(3) algorithms(4) id-dsa-with-sha2(3) 2 } When either of these algorithm identifiers is used, the AlgorithmIdentifier parameters field MUST be absent. 3.2. RSA [RFC3370] section 3.2 specifies the conventions for RSA with SHA-1 (PKCS #1 v1.5) public key algorithm identifiers, parameters, public keys, and signature values. RSA with SHA2 algorithms uses the same conventions for these public key algorithm identifiers, parameters, public keys, and signature values. RSA (PKCS #1 v1.5) MAY be used with SHA-224, SHA-256, SHA-384, or SHA-512. The object identifier for RSA with SHA-224 signature values is: sha224WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 14 } The object identifier for RSA with SHA-256 signature values is: sha256WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 11 } The object identifier for RSA with SHA-384 signature values is: sha384WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 12 } The object identifier for RSA with SHA-512 signature values is: sha512WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 13 } When any of these four object identifiers appears within an AlgorithmIdentifier, the parameters MUST be NULL. Implementations MUST accept the parameters being absent as well as present. 3.3. ECDSA [RFC3278] section 2.1 specifies the conventions for ECDSA with SHA1 public key algorithm identifiers, parameters, public keys, and signature values. ECDSA with SHA2 algorithms uses the same conventions for these public key algorithm identifiers, parameters, public keys, and signature values, except that the digestAlgorithm MUST include the corresponding message digest algorithm identifier, and not the sha-1 object identifier. ECDSA MAY be used with SHA-224, SHA-256, SHA-384, or SHA-512. The algorithm identifier for ECDSA with SHA-224 signature values is: ecdsa-with-SHA224 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 1 } The algorithm identifier for ECDSA with SHA-256 signature values is: ecdsa-with-SHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 2 } The algorithm identifier for ECDSA with SHA-384 signature values is: ecdsa-with-SHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 3 } The algorithm identifier for ECDSA with SHA-512 signature values is: ecdsa-with-SHA512 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 4 } When any of these four object identifiers appears within an AlgorithmIdentifier, the parameters MUSTomit the parameters field. That is, the AlgorithmIdentifier SHALLbe~~NULL.~~a SEQUENCE of one component: the OID ecdsa-with-SHA224, ecdsa-with-SHA256, ecdsa-with-SHA384 or ecdsa-with-SHA512.4. Security Considerations The security considerations in [RFC3278], [RFC3370], [RFC3874], [RFC4055], and [ECCADD] apply. No new security considerations are introduced as a result of this specification. 5. IANA Considerations None: All identifiers are already registered. Please remove this section prior to publication as an RFC. 6. References 6.1. Normative References [ECCADD] Dang, S., Santesson, S., Moriarty, K., and Brown, "Internet X.509 Public Key Infrastructure: Additional Algorithms and Identifiers for DSA and ECDSA", work-in- progress. [DSS]~~Federal Information Processing~~National Institute ofStandardsand Technology (NIST), FIPSPublication~~(FIPS PUB) 186-2,~~186-2:Digital Signature Standard, January 2000. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119. March 1997. [RFC2313] Kaliski, B., "PKCS #1: RSA Encryption Version 1.5", RFC 2313, March 1998. [RFC3278] Blake-Wilson, S., Brown, D., and P. Lambert, "Use of Elliptic Curve Cryptography (ECC) Algorithms in Cryptographic Message Syntax (CMS)", RFC 3278, April 2002. [RFC3370] Housley, R., "Cryptographic Message Syntax (CMS) Algorithms", RFC 3370, August 2002. [RFC3852] Housley, R., "The Cryptographic Message Syntax (CMS)", RFC 3852. July 2004. [RFC3874] Housley, R., "A 224-bit One Way Hash Function: SHA-224", RFC 3874. September 2004. [RFC4055] Schaad, J., Kaliski, B., and R. Housley, "Additional Algorithms and Identifiers for RSA Cryptography for use in the Internet Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 4055. June 2005. [SHS] National Institute of Standards and Technology (NIST), FIPS Publication 180-2: Secure Hash Standard, August 2002. [X9.62] X9.62-2005, "Public Key Cryptography for the Financial Services Industry: The Elliptic Curve Digital Signature Standard (ECDSA)", November, 2005. 6.2. Informative References [RFC4231] Nystrom, A. "Identifiers and Test Vectors for HMAC-SHA- 224, HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512", RFC4231. December 2005. [RFC4634] Eastlake, D., and T. Hansen, "US Secure Hash Algorithms (SHA and HMAC-SHA)", RFC 4634, July 2006. Author's Addresses Sean Turner IECA, Inc. 3057 Nutley Street, Suite 106 Fairfax, VA 22031 USA EMail: turners@ieca.com Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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