Internet-Draft CMP Algorithms June 2022
Brockhaus, et al. Expires 4 December 2022 [Page]
Workgroup:
LAMPS Working Group
Internet-Draft:
draft-ietf-lamps-cmp-algorithms-15
Updates:
4210 (if approved)
Published:
Intended Status:
Standards Track
Expires:
Authors:
H. Brockhaus, Ed.
Siemens
H. Aschauer
Siemens
M. Ounsworth
Entrust
J. Gray
Entrust

Certificate Management Protocol (CMP) Algorithms

Abstract

This document describes the conventions for using several cryptographic algorithms with the Certificate Management Protocol (CMP). CMP is used to enroll and further manage the lifecycle of X.509 certificates. This document also updates the algorithm use profile from RFC 4210 Appendix D.2.

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 4 December 2022.

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Table of Contents

1. Introduction

RFC 4210 Appendix D.2 [RFC4210] contains a set of algorithms, mandatory to be supported by conforming implementations. These algorithms were appropriate at the time CMP was released, but as cryptographic algorithms weaken over time, some of them should not be used anymore. In general, new attacks are emerging due to research cryptoanalysis or increase in computing power. New algorithms were introduced that are more resistant to today's attacks.

This document lists current cryptographic algorithms usable with CMP to offer an easier way maintaining the list of suitable algorithms over time.

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.

In the following sections ASN.1 values and types are used to indicate where algorithm identifier and output values are provided. These ASN.1 values and types are defined in CMP [RFC4210], CRMF [RFC4211], CMP Updates [I-D.ietf-lamps-cmp-updates], or CMS [RFC5652].

2. Message Digest Algorithms

This section provides references to object identifiers and conventions to be employed by CMP implementations that support SHA2 or SHAKE message digest algorithms.

Digest algorithm identifiers are located in:

Digest values are located in:

In addition, digest values are input to signature algorithms.

2.1. SHA2

The SHA2 algorithm family is defined in FIPS Pub 180-4 [NIST.FIPS.180-4].

The message digest algorithms SHA-224, SHA-256, SHA-384, and SHA-512 are identified by the following OIDs:

   id-sha224 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16)
      us(840) organization(1) gov(101) csor(3) nistalgorithm(4)
      hashalgs(2) 4 }
   id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16)
      us(840) organization(1) gov(101) csor(3) nistalgorithm(4)
      hashalgs(2) 1 }
   id-sha384 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16)
      us(840) organization(1) gov(101) csor(3) nistalgorithm(4)
      hashalgs(2) 2 }
   id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16)
      us(840) organization(1) gov(101) csor(3) nistalgorithm(4)
      hashalgs(2) 3 }

Specific conventions to be considered are specified in RFC 5754 Section 2 [RFC5754].

2.2. SHAKE

The SHA-3 family of hash functions is defined in FIPS Pub 202 [NIST.FIPS.202] and includes fixed output length variants SHA3-224, SHA3-256, SHA3-384, and SHA3-512, as well as extendable-output functions (SHAKEs) SHAKE128 and SHAKE256. Currently, SHAKE128 and SHAKE256 are the only members of the SHA3-family which are specified for use in X.509 certificates [RFC8692] and CMS [RFC8702] as one-way hash function for use with RSASSA-PSS and ECDSA.

SHAKE is an extendable-output function and FIPS Pub 202 [NIST.FIPS.202] prohibits using SHAKE as general-purpose hash function. When SHAKE is used in CMP as a message digest algorithm, the output length MUST be 256 bits for SHAKE128 and 512 bits for SHAKE256.

The message digest algorithms SHAKE128 and SHAKE256 are identified by the following OIDs:

   id-shake128 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16)
      us(840) organization(1) gov(101) csor(3) nistAlgorithm(4)
      hashalgs(2) 11 }
   id-shake256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16)
      us(840) organization(1) gov(101) csor(3) nistAlgorithm(4)
      hashalgs(2) 12 }

Specific conventions to be considered are specified in RFC 8702 Section 3.1 [RFC8702].

3. Signature Algorithms

This section provides references to object identifiers and conventions to be employed by CMP implementations that support RSA, ECDSA, or EdDSA signature algorithms.

The signature algorithm is referred to as MSG_SIG_ALG in Section 7.2, RFC 4210 Appendix D and E [RFC4210], and in the Lightweight CMP Profile [I-D.ietf-lamps-lightweight-cmp-profile].

Signature algorithm identifiers are located in:

Signature values are located in:

3.1. RSA

The RSA (RSASSA-PSS and PKCS#1 version 1.5) signature algorithm is defined in RFC 8017 [RFC8017].

The algorithm identifier for RSASAA-PSS signatures used with SHA2 message digest algorithms is identified by the following OID:

   id-RSASSA-PSS OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 10 }

Specific conventions to be considered are specified in RFC 4056 [RFC4056].

The signature algorithm RSASSA-PSS used with SHAKE message digest algorithms are identified by the following OIDs:

   id-RSASSA-PSS-SHAKE128  OBJECT IDENTIFIER  ::=  { iso(1)
      identified-organization(3) dod(6) internet(1) security(5)
      mechanisms(5) pkix(7) algorithms(6) 30 }
   id-RSASSA-PSS-SHAKE256  OBJECT IDENTIFIER  ::=  { iso(1)
      identified-organization(3) dod(6) internet(1) security(5)
      mechanisms(5) pkix(7) algorithms(6) 31 }

Specific conventions to be considered are specified in RFC 8702 Section 3.2.1 [RFC8702].

The signature algorithm PKCS#1 version 1.5 used with SHA2 message digest algorithms is identified by the following OIDs:

   sha224WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1)
      member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 14 }
   sha256WithRSAEncryption  OBJECT IDENTIFIER  ::=  { iso(1)
      member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 11 }
   sha384WithRSAEncryption  OBJECT IDENTIFIER  ::=  { iso(1)
      member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 12 }
   sha512WithRSAEncryption  OBJECT IDENTIFIER  ::=  { iso(1)
      member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 13 }

Specific conventions to be considered are specified in RFC 5754 Section 3.2 [RFC5754].

3.2. ECDSA

The ECDSA signature algorithm is defined in FIPS Pub 186-4 [NIST.FIPS.186-4].

The signature algorithm ECDSA used with SHA2 message digest algorithms is identified by the following OIDs:

   ecdsa-with-SHA224 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 1 }
   ecdsa-with-SHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 2 }
   ecdsa-with-SHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 3 }
   ecdsa-with-SHA512 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 4 }

As specified in RFC 5480 [RFC5480] the NIST-recommended SECP curves are identified by the following OIDs:

   secp192r1 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
       us(840) ansi-X9-62(10045) curves(3) prime(1) 1 }
   secp224r1 OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) curve(0) 33 }
   secp256r1 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
       us(840) ansi-X9-62(10045) curves(3) prime(1) 7 }
   secp384r1 OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) curve(0) 34 }
   secp521r1 OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) curve(0) 35 }

Specific conventions to be considered are specified in RFC 5754 Section 3.3 [RFC5754].

The signature algorithm ECDSA used with SHAKE message digest algorithms are identified by the following OIDs:

   id-ecdsa-with-shake128 OBJECT IDENTIFIER  ::=  { iso(1)
      identified-organization(3) dod(6) internet(1) security(5)
      mechanisms(5) pkix(7) algorithms(6) 32 }
   id-ecdsa-with-shake256 OBJECT IDENTIFIER  ::=  { iso(1)
      identified-organization(3) dod(6) internet(1) security(5)
      mechanisms(5) pkix(7) algorithms(6) 33 }

Specific conventions to be considered are specified in RFC 8702 Section 3.2.2 [RFC8702].

3.3. EdDSA

The EdDSA signature algorithm is defined in RFC 8032 Section 3.3 [RFC8032] and FIPS Pub 186-5 (Draft) [NIST.FIPS.186-5].

The signature algorithm Ed25519 that MUST be used with SHA-512 message digest algorithms is identified by the following OIDs:

   id-Ed25519 OBJECT IDENTIFIER  ::=  { iso(1)
      identified-organization(3) thawte(101) 112 }

The signature algorithm Ed448 that MUST be used with SHAKE256 message digest algorithms is identified by the following OIDs:

   id-Ed448 OBJECT IDENTIFIER  ::=  { iso(1)
      identified-organization(3) thawte(101) 113 }

Specific conventions to be considered are specified in RFC 8419 [RFC8419].

Note: The hash algorithm used to calculate the certHash in certConf messages MUST be SHA512 if the certificate to be confirmed has been signed using Ed25519 and SHAKE256 with d=512 if signed using Ed448.

4. Key Management Algorithms

CMP utilizes the following general key management techniques: key agreement, key transport, and passwords.

CRMF [RFC4211] and CMP Updates [I-D.ietf-lamps-cmp-updates] promotes the use of CMS [RFC5652] EnvelopedData by deprecating the use of EncryptedValue.

4.1. Key Agreement Algorithms

The key agreement algorithm is referred to as PROT_ENC_ALG in RFC 4210 Appendix D and E [RFC4210] and as KM_KA_ALG in the Lightweight CMP Profile [I-D.ietf-lamps-lightweight-cmp-profile], as well as in Section 7.

Key agreement algorithms are only used in CMP when using CMS [RFC5652] EnvelopedData together with the key agreement key management technique. When a key agreement algorithm is used, a key-encryption algorithm (Section 4.3) is needed next to the content-encryption algorithm (Section 5).

Key agreement algorithm identifiers are located in:

  • keyEncryptionAlgorithm field of KeyAgreeRecipientInfo

Key wrap algorithm identifiers are located in:

  • KeyWrapAlgorithm parameters within keyEncryptionAlgorithm field of KeyAgreeRecipientInfo

Wrapped content-encryption keys are located in:

  • encryptedKey field of RecipientEncryptedKeys

4.1.1. Diffie-Hellman

Diffie-Hellman key agreement is defined in RFC 2631 [RFC2631] and SHALL be used in the ephemeral-static as specified in RFC 3370 [RFC3370]. Static-static variants SHALL NOT be used.

The Diffie-Hellman key agreement algorithm is identified by the following OID:

   id-alg-ESDH OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 5 }

Specific conventions to be considered are specified in RFC 3370 Section 4.1 [RFC3370].

4.1.2. ECDH

Elliptic Curve Diffie-Hellman (ECDH) key agreement is defined in RFC 5753 [RFC5753] and SHALL be used in the ephemeral-static variant as specified in RFC 5753 [RFC5753] or the 1-Pass ECMQV variant as specified in RFC 5753 [RFC5753]. Static-static variants SHALL NOT be used.

The ECDH key agreement algorithm used together with NIST-recommended SECP curves are identified by the following OIDs:

   dhSinglePass-stdDH-sha224kdf-scheme OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) schemes(1) 11(11) 0 }
   dhSinglePass-stdDH-sha256kdf-scheme OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) schemes(1) 11(11) 1 }
   dhSinglePass-stdDH-sha384kdf-scheme OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) schemes(1) 11(11) 2 }
   dhSinglePass-stdDH-sha512kdf-scheme OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) schemes(1) 11(11) 3 }
   dhSinglePass-cofactorDH-sha224kdf-scheme OBJECT IDENTIFIER ::= {
       iso(1) identified-organization(3) certicom(132) schemes(1)
       14(14) 0 }
   dhSinglePass-cofactorDH-sha256kdf-scheme OBJECT IDENTIFIER ::= {
       iso(1) identified-organization(3) certicom(132) schemes(1)
       14(14) 1 }
   dhSinglePass-cofactorDH-sha384kdf-scheme OBJECT IDENTIFIER ::= {
       iso(1) identified-organization(3) certicom(132) schemes(1)
       14(14) 2 }
   dhSinglePass-cofactorDH-sha512kdf-scheme OBJECT IDENTIFIER ::= {
       iso(1) identified-organization(3) certicom(132) schemes(1)
       14(14) 3 }
   mqvSinglePass-sha224kdf-scheme OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) schemes(1) 15(15) 0 }
   mqvSinglePass-sha256kdf-scheme OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) schemes(1) 15(15) 1 }
   mqvSinglePass-sha384kdf-scheme OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) schemes(1) 15(15) 2 }
   mqvSinglePass-sha512kdf-scheme OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) schemes(1) 15(15) 3 }

As specified in RFC 5480 [RFC5480] the NIST-recommended SECP curves are identified by the following OIDs:

   secp192r1 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
       us(840) ansi-X9-62(10045) curves(3) prime(1) 1 }
   secp224r1 OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) curve(0) 33 }
   secp256r1 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
       us(840) ansi-X9-62(10045) curves(3) prime(1) 7 }
   secp384r1 OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) curve(0) 34 }
   secp521r1 OBJECT IDENTIFIER ::= { iso(1)
       identified-organization(3) certicom(132) curve(0) 35 }

Specific conventions to be considered are specified in RFC 5753 [RFC5753].

The ECDH key agreement algorithm used together with curve25519 or curve448 are identified by the following OIDs:

   id-X25519 OBJECT IDENTIFIER ::= { iso(1)
      identified-organization(3) thawte(101) 110 }
   id-X448 OBJECT IDENTIFIER ::= { iso(1)
      identified-organization(3) thawte(101) 111 }

Specific conventions to be considered are specified in RFC 8418 [RFC8418].

4.2. Key Transport Algorithms

The key transport algorithm is also referred to as PROT_ENC_ALG in RFC 4210 Appendix D and E [RFC4210] and as KM_KL_ALG in the Lightweight CMP Profile [I-D.ietf-lamps-lightweight-cmp-profile], as well as in Section 7.

Key transport algorithms are only used in CMP when using CMS [RFC5652] EnvelopedData together with the key transport key management technique.

Key transport algorithm identifiers are located in:

  • keyEncryptionAlgorithm field of KeyTransRecipientInfo

Key transport encrypted content-encryption keys are located in:

  • encryptedKey field of KeyTransRecipientInfo

4.2.1. RSA

The RSA key transport algorithm is the RSA encryption scheme defined in RFC 8017 [RFC8017].

The algorithm identifier for RSA (PKCS #1 v1.5) is:

   rsaEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 1 }

The algorithm identifier for RSAES-OAEP is:

   id-RSAES-OAEP  OBJECT IDENTIFIER  ::=  { iso(1) member-body(2)
      us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 7 }

Further conventions to be considered for PKCS #1 v1.5 are specified in RFC 3370 Section 4.2.1 [RFC3370] and for RSAES-OAEP in RFC 3560 [RFC3560].

4.3. Symmetric Key-Encryption Algorithms

The symmetric key-encryption algorithm is also referred to as KM_KW_ALG in Section 7.2 and in the Lightweight CMP Profile [I-D.ietf-lamps-lightweight-cmp-profile].

As symmetric key-encryption key management technique is not used by CMP, the symmetric key-encryption algorithm is only needed when using the key agreement or password-based key management technique with CMS [RFC5652] EnvelopedData.

Key wrap algorithm identifiers are located in:

  • parameters field of the KeyEncryptionAlgorithmIdentifier of KeyAgreeRecipientInfo and PasswordRecipientInfo

Wrapped content-encryption keys are located in:

  • encryptedKey field of RecipientEncryptedKeys (for key agreement) and PasswordRecipientInfo (for password-based key management)

4.3.1. AES Key Wrap

The AES encryption algorithm is defined in FIPS Pub 197 [NIST.FIPS.197] and the key wrapping is defined in RFC 3394 [RFC3394].

AES key encryption has the algorithm identifier:

   id-aes128-wrap OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) aes(1) 5 }
   id-aes192-wrap OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) aes(1) 25 }
   id-aes256-wrap OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) aes(1) 45 }

The underlying encryption functions for the key wrap and content-encryption algorithms (as specified in Section 5) and the key sizes for the two algorithms MUST be the same (e.g., AES-128 key wrap algorithm with AES-128 content-encryption algorithm), see also RFC 8551 [RFC8551].

Further conventions to be considered for AES key wrap are specified in RFC 3394 Section 2.2 [RFC3394] and RFC 3565 Section 2.3.2 [RFC3565].

4.4. Key Derivation Algorithms

The key derivation algorithm is also referred to as KM_KD_ALG in Section 7.2 and in the Lightweight CMP Profile [I-D.ietf-lamps-lightweight-cmp-profile].

Key derivation algorithms are only used in CMP when using CMS [RFC5652] EnvelopedData together with password-based key management technique.

Key derivation algorithm identifiers are located in:

  • keyDerivationAlgorithm field of PasswordRecipientInfo

When using the password-based key management technique with EnvelopedData as specified in CMP Updates together with message authentication code (MAC)-based PKIProtection, the salt for the password-based MAC and KDF must be chosen independently to ensure usage of independent symmetric keys.

4.4.1. PBKDF2

The password-based key derivation function 2 (PBKDF2) is defined in RFC 8018 [RFC8018].

Password-based key derivation function 2 has the algorithm identifier:

   id-PBKDF2 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
      rsadsi(113549) pkcs(1) pkcs-5(5) 12 }

Further conventions to be considered for PBKDF2 are specified in RFC 3370 Section 4.4.1 [RFC3370] and RFC 8018 Section 5.2 [RFC8018].

5. Content Encryption Algorithms

The content encryption algorithm is also referred to as PROT_SYM_ALG in Section 7, RFC 4210 Appendix D and E [RFC4210], and the Lightweight CMP Profile [I-D.ietf-lamps-lightweight-cmp-profile].

Content encryption algorithms are only used in CMP when using CMS [RFC5652] EnvelopedData to transport a signed private key package in case of central key generation or key archiving, a certificate to facilitate implicit proof-of-possession, or a revocation passphrase in encrypted form.

Content encryption algorithm identifiers are located in:

Encrypted content is located in:

5.1. AES-CBC

The AES encryption algorithm is defined in FIPS Pub 197 [NIST.FIPS.197].

AES-CBC content encryption has the algorithm identifier:

   id-aes128-CBC OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) aes(1) 2 }
   id-aes192-CBC OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) aes(1)22 }
   id-aes256-CBC OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) aes(1)42 }

Specific conventions to be considered for AES-CBC content encryption are specified in RFC 3565 [RFC3565].

6. Message Authentication Code Algorithms

The message authentication code (MAC) is either used for shared secret-based CMP message protection or together with the password-based key derivation function (PBKDF2).

The message authentication code algorithm is also referred to as MSG_MAC_ALG in Section 7, RFC 4210 Appendix D and E [RFC4210], and the Lightweight CMP Profile [I-D.ietf-lamps-lightweight-cmp-profile].

6.1. Password-Based MAC

Password-based message authentication code (MAC) algorithms combine the derivation of a symmetric key from a password or other shared secret information and a symmetric key-based MAC function as specified in Section 6.2 using this derived key.

Message authentication code algorithm identifiers are located in:

  • protectionAlg field of PKIHeader

Message authentication code values are located in:

  • PKIProtection field of PKIMessage

6.1.1. PasswordBasedMac

The PasswordBasedMac algorithm is defined in RFC 4210 Section 5.1.3.1 [RFC4210], RFC 4211 Section 4.4 [RFC4211], and Algorithm Requirements Update to the Internet X.509 Public Key Infrastructure Certificate Request Message Format (CRMF) [RFC9045].

The PasswordBasedMac algorithm is identified by the following OID:

   id-PasswordBasedMac OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) nt(113533) nsn(7) algorithms(66) 13 }

Further conventions to be considered for password-based MAC are specified in RFC 4210 Section 5.1.3.1 [RFC4210], RFC 4211 Section 4.4 [RFC4211], and Algorithm Requirements Update to the Internet X.509 Public Key Infrastructure Certificate Request Message Format (CRMF) [RFC9045].

6.1.2. PBMAC1

The Password-Based Message Authentication Code 1 (PBMAC1) is defined in RFC 8018 [RFC8018]. PBMAC1 combines a password-based key derivation function like PBKDF2 (Section 4.4.1) with an underlying symmetric key-based message authentication scheme.

PBMAC1 has the following OID:

   id-PBMAC1 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
      rsadsi(113549) pkcs(1) pkcs-5(5) 14 }

Specific conventions to be considered for PBMAC1 are specified in RFC 8018 Section 7.1 and A.5 [RFC8018].

6.2. Symmetric Key-Based MAC

Symmetric key-based message authentication code (MAC) algorithms are used for deriving the symmetric encryption key when using PBKDF2 as described in Section 4.4.1 as well as with Password-based MAC as described in Section 6.1.

Message authentication code algorithm identifiers are located in:

  • protectionAlg field of PKIHeader
  • messageAuthScheme field of PBMAC1
  • mac field of PBMParameter
  • prf field of PBKDF2-params

Message authentication code values are located in:

  • PKIProtection field of PKIMessage

6.2.1. SHA2-Based HMAC

The HMAC algorithm is defined in RFC 2104 [RFC2104] and FIPS Pub 198-1 [NIST.FIPS.198-1].

The HMAC algorithm used with SHA2 message digest algorithms is identified by the following OIDs:

   id-hmacWithSHA224 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) rsadsi(113549) digestAlgorithm(2) 8 }
   id-hmacWithSHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) rsadsi(113549) digestAlgorithm(2) 9 }
   id-hmacWithSHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) rsadsi(113549) digestAlgorithm(2) 10 }
   id-hmacWithSHA512 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) rsadsi(113549) digestAlgorithm(2) 11 }

Specific conventions to be considered for SHA2-based HMAC are specified in RFC 4231 Section 3.1 [RFC4231].

6.2.2. AES-GMAC

The AES-GMAC algorithm is defined in FIPS Pub 197 [NIST.FIPS.197] and NIST SP 800-38d [NIST.SP.800-38d].

Note: AES-GMAC MUST NOT be used twice with the same parameter set, especially the same nonce. Therefore, it MUST NOT be used together with PBKDF2. When using it with PBMAC1 it MUST be ensured that AES-GMAC is only used as message authentication scheme and not for the key derivation function PBKDF2.

The AES-GMAC algorithm is identified by the following OIDs:

   id-aes128-GMAC OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) aes(1) 9 }
   id-aes192-GMAC OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) aes(1) 29 }
   id-aes256-GMAC OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) aes(1) 49 }

Specific conventions to be considered for AES-GMAC are specified in RFC 9044 [RFC9044].

6.2.3. SHAKE-Based KMAC

The KMAC algorithm is defined in RFC 8702 [RFC8702] and FIPS SP 800-185 [NIST.SP.800-185].

The SHAKE-based KMAC algorithm is identified by the following OIDs:

   id-KmacWithSHAKE128 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) 2 19 }
   id-KmacWithSHAKE256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
      country(16) us(840) organization(1) gov(101) csor(3)
      nistAlgorithm(4) 2 20 }

Specific conventions to be considered for KMAC with SHAKE are specified in RFC 8702 Section 3.4 [RFC8702].

7. Algorithm Use Profiles

This section provides profiles of algorithms and respective conventions for different application use cases.

Recommendations like NIST SP 800-57 Recommendation for Key Management Table 2 [NIST.SP.800-57pt1r5] and ECRYPT Algorithms, Key Size and Protocols Report (2018) Section 4.6 [ECRYPT.CSA.D5.4] provide general information on current cryptographic algorithms.

The overall cryptographic strength of a CMP deployment will depend on several factors, including:

The following table shows the algorithms listed in this document sorted by their bits of security. If an implementation intends to enroll and manage certificate for keys of a specific security, it SHALL implement and use algorithms of at least that strength for the respective PKI management operation. If one row does not provide a suitable algorithm, the implementer MUST choose one offering more bits of security.

Table 1: Cryptographic Algorithms Sorted by their Bits of Security
Bits of Secu-
rity		 RSA or DH Elliptic Curve Hash Function or XOF with Specified Output Length (d) Symmetric Encryption
112 RSA2048,
DH(2048)		 ECDSA/ECDH (secp224r1) SHA224
128 RSA3072,
DH(3072)		 ECDSA/ECDH (secp256r1),
Ed25519/X25519 (Curve25519)		 SHA256,
SHAKE128(d=256)		 AES-128
192 ECDSA/ECDH (secp384r1) SHA384 AES-192
224 Ed448/X448 (Curve448)
256 ECDSA/ECDH (secp521r1) SHA512,
SHAKE256(d=512)		 AES-256

The following table shows the cryptographic algorithms sorted by their usage in CMP and with more details.

Table 2: Cryptographic Algorithms Sorted by their Bits of Security and Usage by CMP
Bits of
Security		 Key Types to Be Certified CMP Protection Key Management Technique Key-Wrap and Symmetric Encryption
MSG_SIG_ALG, MSG_MAC_ALG PROT_ENC_ALG or KM_KA_ALG, KM_KT_ALG, KM_KD_ALG PROT_SYM_ALG,
SYM_PENC_ALG
or
KM_KW_ALG
112 RSA2048,
secp224r1		 RSASSA-PSS (2048, SHA224 or SHAKE128 (d=256)),
RSAEncryption (2048, SHA224),
ECDSA (secp224r1, SHA224 or SHAKE128 (d=256)),
PBMAC1 (HMAC-SHA224)		 DH(2048),
RSAES-OAEP (2048, SHA224),
RSAEncryption (2048, SHA224),
ECDH (secp224r1, SHA224),
PBKDF2 (HMAC-SHA224)
128 RSA3072,
secp256r1,
Curve25519		 RSASSA-PSS (3072, SHA256 or SHAKE128 (d=256)),
RSAEncryption (3072, SHA256),
ECDSA (secp256r1, SHA256 or SHAKE128 (d=256)),
Ed25519 (SHA512),
PBMAC1 (HMAC-SHA256)		 DH(3072),
RSAES-OAEP (3072, SHA256),
RSAEncryption (3072, SHA256),
ECDH (secp256r1, SHA256),
X25519,
PBKDF2 (HMAC-SHA256)		 AES-128
192 secp384r1 ECDSA (secp384r1, SHA384),
PBMAC1 (HMAC-SHA384)		 ECDH (secp384r1, SHA384),
PBKDF2 (HMAC-SHA384)		 AES-192
224 Curve448 Ed448 (SHAKE256) X448
256 secp521r1 ECDSA (secp521r1, SHA512 or SHAKE256 (d=512)),
PBMAC1 (HMAC-SHA512)		 ECDH (secp521r1, SHA512),
PBKDF2 (HMAC-SHA512)		 AES-256

To avoid consuming too many computational resources it is recommended to choose a set of algorithms offering roughly the same level of security. Below are provided several algorithm profiles which are balanced, assuming the implementer chooses MAC secrets and/or certificate profiles of at least equivalent strength.

7.1. Algorithm Profile for RFC 4210 PKI Management Message Profiles

The following table updates the definitions of algorithms used within PKI Management Message Profiles as defined in CMP Appendix D.2 [RFC4210].

The columns in the table are:

Name: An identifier used for message profiles

Use: Description of where and for what the algorithm is used

Mandatory: Algorithms which MUST be supported by conforming implementations

Optional: Algorithms which are OPTIONAL to support

Deprecated: Algorithms from RFC 4210 [RFC4210] which SHOULD NOT be used any more

Table 3: Algorithms Used Within RFC 4210 Appendix D.2
Name Use Manda-
tory		 Optional Deprecated
MSG_SIG_ALG protection of PKI messages using signature RSA ECDSA, EdDSA DSA, combinations with MD5 and SHA-1
MSG_MAC_ALG protection of PKI messages using MACing PBMAC1 PasswordBasedMac, HMAC, KMAC X9.9
SYM_PENC_ALG symmetric encryption of an end entity's private key where symmetric key is distributed out-of-band AES-wrap 3-DES(3-key-EDE, CBC Mode), RC5, CAST-128
PROT_ENC_ALG asymmetric algorithm used for encryption of (symmetric keys for encryption of) private keys transported in PKIMessages DH ECDH, RSA
PROT_SYM_ALG symmetric encryption algorithm used for encryption of private key bits (a key of this type is encrypted using PROT_ENC_ALG) AES-CBC 3-DES(3-key-EDE, CBC Mode), RC5, CAST-128

Mandatory Algorithm Identifiers and Specifications:

RSA: sha256WithRSAEncryption with 2048 bit, see Section 3.1

PasswordBasedMac: id-PasswordBasedMac, see Section 6.1 (with id-sha256 as the owf parameter, see Section 2.1 and id-hmacWithSHA256 as the mac parameter, see Section 6.2.1)

PBMAC1: id-PBMAC1, see Section 6.1.2 (with id-PBKDF2 as the key derivation function, see Section 4.4.1 and id-hmacWithSHA256 as message authentication scheme, see Section 6.2.1). It is RECOMMENDED to prefer the usage of PBMAC1 instead of PasswordBasedMac.

DH: id-alg-ESDH, see Section 4.1.1

AES-wrap: id-aes128-wrap, see Section 4.3.1

AES-CBC: id-aes128-CBC, see Section 5.1

7.2. Algorithm Profile for Lightweight CMP Profile

The following table contains definitions of algorithms which MAY be supported by implementations of the Lightweight CMP Profile [I-D.ietf-lamps-lightweight-cmp-profile].

As the set of algorithms to be used for implementations of the Lightweight CMP Profile heavily depends on the PKI management operations implemented, the certificates used for messages protection, and the certificates to be managed, this document will not specify a specific set that is mandatory to support for conforming implementations.

The columns in the table are:

Name: An identifier used for message profiles

Use: Description of where and for what the algorithm is used

Examples: Lists the algorithms as described in this document. The list of algorithms depends on the set of PKI management operations to be implemented.

Note: It is RECOMMENDED to prefer the usage of PBMAC1 instead of PasswordBasedMac.

Table 4: Algorithms Used Within Lightweight CMP Profile
Name Use Examples
MSG_SIG_ALG protection of PKI messages using signature and for SignedData, e.g., a private key transported in PKIMessages RSA, ECDSA, EdDSA
MSG_MAC_ALG protection of PKI messages using MACing PasswordBasedMac (see Section 9), PBMAC1, HMAC, KMAC
KM_KA_ALG asymmetric key agreement algorithm used for agreement of a symmetric key for use with KM_KW_ALG DH, ECDH
KM_KT_ALG asymmetric key encryption algorithm used for transport of a symmetric key for PROT_SYM_ALG RSA
KM_KD_ALG symmetric key derivation algorithm used for derivation of a symmetric key for use with KM_KW_ALG PBKDF2
KM_KW_ALG algorithm to wrap a symmetric key for PROT_SYM_ALG AES-wrap
PROT_SYM_ALG symmetric content encryption algorithm used for encryption of EnvelopedData, e.g., a private key transported in PKIMessages AES-CBC

8. IANA Considerations

This document does not request changes to the IANA registry.

9. Security Considerations

This document lists many cryptographic algorithms usable with CMP to offer implementer a more up-to-date choice. Finally, the algorithms to be supported also heavily depend on the certificates and PKI management operations utilized in the target environment. The algorithm with the lowest security strength and the entropy of shared secret information define the security of the overall solution, see Section 7.

When using MAC-based message protection the use of PBMAC1 is preferable to that of PasswordBasedMac. First, PBMAC1 is a well-known scrutinized algorithm, which is not true for PasswordBasedMac. Second, the PasswordBasedMac algorithm as specified in RFC 4211 Section 4.4 [RFC4211] is essentially PBKDF1 (as defined in RFC 8018 Section 5.1 [RFC8018]) with an HMAC step at the end. Here we update to use the PBKDF2-HMAC construct defined as PBMAC1 in [RFC8018]. PBKDF2 is superior to PBKDF1 in an improved internal construct for iterated hashing, and in removing PBKDF1's limitation of only being able to derive keys up to the size of the underlying hash function. Additionally, PBKDF1 is not recommended for new applications as stated in Section 5.1 of RFC 8018 [RFC8018] and no longer an approved algorithm by most standards bodies, and therefore presents difficulties to implementer who are submitting their CMP implementations for certification, hence moving to a PBKDF2-based mechanism. This change is in alignment with [RFC9045] which updates [RFC4211] to allow the use of PBMAC1 in CRMF.

AES-GMAC MUST NOT be used as the pseudo random function in PBKDF2; the use of AES-GMAC more than once with the same key and the same nonce will break the security.

In Section 7 of this document there is also an update to the Appendix D.2 of RFC 4210 [RFC4210] and a set of algorithms that MAY be supported when implementing the Lightweight CMP Profile [I-D.ietf-lamps-lightweight-cmp-profile].

It is recognized that there may be older CMP implementations in use that conform to the algorithm use profile from Appendix D.2 of RFC 4210 [RFC4210]. For example, the use of AES is now mandatory for PROT_SYM_ALG but in RFC 4210 [RFC4210] 3-DES was mandatory. Therefore, it is expected that many CMP systems may already support the recommended algorithms in this specification. In such systems the weakened algorithms should be disabled from further use. If critical systems cannot be immediately updated to conform to the recommended algorithm use profile, it is recommended a plan to migrate the infrastructure to conforming profiles be adopted as soon as possible.

Symmetric key-based MAC algorithms as described in Section 6.2 MAY be used as MSG_MAC_ALG. The implementer MUST choose a suitable PRF and ensure that the key has sufficient entropy to match the overall security level of the algorithm profile. These considerations are outside the scope of the profile.

10. Acknowledgements

Thanks to Russ Housley for supporting this draft with submitting [RFC9044] and [RFC9045].

May thanks also to all reviewers like Serge Mister, Mark Ferreira, Yuefei Lu, Tomas Gustavsson, Lijun Liao, David von Oheimb and Steffen Fries for their input and feedback to this document. Apologies to all not mentioned reviewers and supporters.

11. Normative References

[I-D.ietf-lamps-cmp-updates]
Brockhaus, H., Oheimb, D. V., and J. Gray, "Certificate Management Protocol (CMP) Updates", Work in Progress, Internet-Draft, draft-ietf-lamps-cmp-updates-20, , <https://datatracker.ietf.org/doc/html/draft-ietf-lamps-cmp-updates-20>.
[I-D.ietf-lamps-lightweight-cmp-profile]
Brockhaus, H., Oheimb, D. V., and S. Fries, "Lightweight Certificate Management Protocol (CMP) Profile", Work in Progress, Internet-Draft, draft-ietf-lamps-lightweight-cmp-profile-12, , <https://datatracker.ietf.org/doc/html/draft-ietf-lamps-lightweight-cmp-profile-12>.
[NIST.FIPS.180-4]
Dang, Quynh H., "Secure Hash Standard", NIST NIST FIPS 180-4, DOI 10.6028/NIST.FIPS.180-4, , <https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf>.
[NIST.FIPS.186-4]
National Institute of Standards and Technology (NIST), "Digital Signature Standard (DSS)", NIST NIST FIPS 186-4, DOI 10.6028/NIST.FIPS.186-4, , <https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf>.
[NIST.FIPS.186-5]
National Institute of Standards and Technology (NIST), "FIPS Pub 186-5 (Draft): Digital Signature Standard (DSS)", , <https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-5-draft.pdf>.
[NIST.FIPS.197]
National Institute of Standards and Technology (NIST), "Advanced encryption standard (AES)", NIST NIST FIPS 197, DOI 10.6028/NIST.FIPS.197, , <https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.197.pdf>.
[NIST.FIPS.198-1]
National Institute of Standards and Technology (NIST), "The Keyed-Hash Message Authentication Code (HMAC)", NIST NIST FIPS 198-1, DOI 10.6028/NIST.FIPS.198-1, , <https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.198-1.pdf>.
[NIST.FIPS.202]
Dworkin, Morris J., "SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions", NIST NIST FIPS 202, DOI 10.6028/NIST.FIPS.202, , <https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf>.
[NIST.SP.800-185]
Kelsey, John., Change, Shu-jen., and Ray. Perlner, "SHA-3 derived functions: cSHAKE, KMAC, TupleHash and ParallelHash", NIST NIST SP 800-185, DOI 10.6028/NIST.SP.800-185, , <https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-185.pdf>.
[NIST.SP.800-38d]
Dworkin, M J., "Recommendation for block cipher modes of operation :GaloisCounter Mode (GCM) and GMAC", NIST NIST SP 800-38d, DOI 10.6028/NIST.SP.800-38d, , <https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf>.
[RFC2104]
Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-Hashing for Message Authentication", RFC 2104, DOI 10.17487/RFC2104, , <https://www.rfc-editor.org/info/rfc2104>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC2631]
Rescorla, E., "Diffie-Hellman Key Agreement Method", RFC 2631, DOI 10.17487/RFC2631, , <https://www.rfc-editor.org/info/rfc2631>.
[RFC3370]
Housley, R., "Cryptographic Message Syntax (CMS) Algorithms", RFC 3370, DOI 10.17487/RFC3370, , <https://www.rfc-editor.org/info/rfc3370>.
[RFC3394]
Schaad, J. and R. Housley, "Advanced Encryption Standard (AES) Key Wrap Algorithm", RFC 3394, DOI 10.17487/RFC3394, , <https://www.rfc-editor.org/info/rfc3394>.
[RFC3560]
Housley, R., "Use of the RSAES-OAEP Key Transport Algorithm in Cryptographic Message Syntax (CMS)", RFC 3560, DOI 10.17487/RFC3560, , <https://www.rfc-editor.org/info/rfc3560>.
[RFC3565]
Schaad, J., "Use of the Advanced Encryption Standard (AES) Encryption Algorithm in Cryptographic Message Syntax (CMS)", RFC 3565, DOI 10.17487/RFC3565, , <https://www.rfc-editor.org/info/rfc3565>.
[RFC4056]
Schaad, J., "Use of the RSASSA-PSS Signature Algorithm in Cryptographic Message Syntax (CMS)", RFC 4056, DOI 10.17487/RFC4056, , <https://www.rfc-editor.org/info/rfc4056>.
[RFC4210]
Adams, C., Farrell, S., Kause, T., and T. Mononen, "Internet X.509 Public Key Infrastructure Certificate Management Protocol (CMP)", RFC 4210, DOI 10.17487/RFC4210, , <https://www.rfc-editor.org/info/rfc4210>.
[RFC4211]
Schaad, J., "Internet X.509 Public Key Infrastructure Certificate Request Message Format (CRMF)", RFC 4211, DOI 10.17487/RFC4211, , <https://www.rfc-editor.org/info/rfc4211>.
[RFC4231]
Nystrom, M., "Identifiers and Test Vectors for HMAC-SHA-224, HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512", RFC 4231, DOI 10.17487/RFC4231, , <https://www.rfc-editor.org/info/rfc4231>.
[RFC5480]
Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk, "Elliptic Curve Cryptography Subject Public Key Information", RFC 5480, DOI 10.17487/RFC5480, , <https://www.rfc-editor.org/info/rfc5480>.
[RFC5652]
Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, RFC 5652, DOI 10.17487/RFC5652, , <https://www.rfc-editor.org/info/rfc5652>.
[RFC5753]
Turner, S. and D. Brown, "Use of Elliptic Curve Cryptography (ECC) Algorithms in Cryptographic Message Syntax (CMS)", RFC 5753, DOI 10.17487/RFC5753, , <https://www.rfc-editor.org/info/rfc5753>.
[RFC5754]
Turner, S., "Using SHA2 Algorithms with Cryptographic Message Syntax", RFC 5754, DOI 10.17487/RFC5754, , <https://www.rfc-editor.org/info/rfc5754>.
[RFC8017]
Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch, "PKCS #1: RSA Cryptography Specifications Version 2.2", RFC 8017, DOI 10.17487/RFC8017, , <https://www.rfc-editor.org/info/rfc8017>.
[RFC8018]
Moriarty, K., Ed., Kaliski, B., and A. Rusch, "PKCS #5: Password-Based Cryptography Specification Version 2.1", RFC 8018, DOI 10.17487/RFC8018, , <https://www.rfc-editor.org/info/rfc8018>.
[RFC8032]
Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital Signature Algorithm (EdDSA)", RFC 8032, DOI 10.17487/RFC8032, , <https://www.rfc-editor.org/info/rfc8032>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[RFC8418]
Housley, R., "Use of the Elliptic Curve Diffie-Hellman Key Agreement Algorithm with X25519 and X448 in the Cryptographic Message Syntax (CMS)", RFC 8418, DOI 10.17487/RFC8418, , <https://www.rfc-editor.org/info/rfc8418>.
[RFC8419]
Housley, R., "Use of Edwards-Curve Digital Signature Algorithm (EdDSA) Signatures in the Cryptographic Message Syntax (CMS)", RFC 8419, DOI 10.17487/RFC8419, , <https://www.rfc-editor.org/info/rfc8419>.
[RFC8702]
Kampanakis, P. and Q. Dang, "Use of the SHAKE One-Way Hash Functions in the Cryptographic Message Syntax (CMS)", RFC 8702, DOI 10.17487/RFC8702, , <https://www.rfc-editor.org/info/rfc8702>.
[RFC9044]
Housley, R., "Using the AES-GMAC Algorithm with the Cryptographic Message Syntax (CMS)", RFC 9044, DOI 10.17487/RFC9044, , <https://www.rfc-editor.org/info/rfc9044>.
[RFC9045]
Housley, R., "Algorithm Requirements Update to the Internet X.509 Public Key Infrastructure Certificate Request Message Format (CRMF)", RFC 9045, DOI 10.17487/RFC9045, , <https://www.rfc-editor.org/info/rfc9045>.

12. Informative References

[ECRYPT.CSA.D5.4]
University of Bristol, "Algorithms, Key Size and Protocols Report (2018)", , <https://www.ecrypt.eu.org/csa/documents/D5.4-FinalAlgKeySizeProt.pdf>.
[NIST.SP.800-57pt1r5]
Barker, Elaine., "Recommendation for key management:part 1 - general", NIST NIST SP 800-57pt1r5, DOI 10.6028/NIST.SP.800-57pt1r5, , <https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-57pt1r5.pdf>.
[RFC8551]
Schaad, J., Ramsdell, B., and S. Turner, "Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 4.0 Message Specification", RFC 8551, DOI 10.17487/RFC8551, , <https://www.rfc-editor.org/info/rfc8551>.
[RFC8692]
Kampanakis, P. and Q. Dang, "Internet X.509 Public Key Infrastructure: Additional Algorithm Identifiers for RSASSA-PSS and ECDSA Using SHAKEs", RFC 8692, DOI 10.17487/RFC8692, , <https://www.rfc-editor.org/info/rfc8692>.

Appendix A. History of Changes

Note: This appendix will be deleted in the final version of the document.

From version 14 -> 15:

From version 13 -> 14:

From version 12 -> 13:

From version 11 -> 12:

From version 10 -> 11:

From version 09 -> 10:

From version 08 -> 09:

From version 07 -> 08:

From version 06 -> 07:

From version 05 -> 06:

From version 04 -> 05:

From version 03 -> 04:

From version 02 -> 03:

From version 01 -> 02:

From version 00 -> 01:

Authors' Addresses

Hendrik Brockhaus (editor)
Siemens AG
Hans Aschauer
Siemens AG
Mike Ounsworth
Entrust
John Gray
Entrust