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RFC 5753

Use of Elliptic Curve Cryptography (ECC) Algorithms in Cryptographic Message Syntax (CMS)

Pages: 61
Informational
Errata
Obsoletes:  3278
Part 2 of 3 – Pages 11 to 33
First   Prev   Next

Top   ToC   RFC5753 - Page 11   prevText

4. AuthenticatedData and AuthEnvelopedData Using ECC

This section describes how to use ECC algorithms with the CMS AuthenticatedData format. AuthenticatedData lacks non-repudiation, and so in some instances is preferable to SignedData. (For example, the sending agent might not want the message to be authenticated when forwarded.) This section also describes how to use ECC algorithms with the CMS AuthEnvelopedData format [CMS-AUTHENV]. AuthEnvelopedData supports authentication and encryption, and in some instances is preferable to signing and then encrypting data. For both AuthenticatedData and AuthEnvelopedData, data origin authentication with 1-Pass ECMQV can only be provided when there is one and only one recipient. When there are multiple recipients, an attack is possible where one recipient modifies the content without other recipients noticing [BON]. A sending agent who is concerned with such an attack SHOULD use a separate AuthenticatedData or AuthEnvelopedData for each recipient. Using an algorithm with the sender static key pair allows for knowledge of the message creator; this means that authentication can, in some circumstances, be obtained for AuthEnvelopedData and AuthenticatedData. This means that 1-Pass ECMQV can be a common algorithm for EnvelopedData, AuthenticatedData, and AuthEnvelopedData while ECDH can only be used in EnvelopedData.

4.1. AuthenticatedData Using 1-Pass ECMQV

This section describes how to use the 1-Pass ECMQV key agreement algorithm with AuthenticatedData. ECMQV is method C(1, 2, ECC MQV) from [SP800-56A]. When using ECMQV with AuthenticatedData, the fields of AuthenticatedData are as in [CMS], but with the following restrictions: - macAlgorithm MUST contain the algorithm identifier of the message authentication code (MAC) algorithm (see Section 7.1.7), which MUST be one of the following: hmac-SHA1, id-hmacWITHSHA224, id- hmacWITHSHA256, id-hmacWITHSHA384, or id-hmacWITHSHA512. - digestAlgorithm MUST contain the algorithm identifier of the hash algorithm (see Section 7.1.1), which MUST be one of the following: id-sha1, id-sha224, id-sha256, id-sha384, or id-sha512.
Top   ToC   RFC5753 - Page 12
   As 1-Pass ECMQV is a key agreement algorithm, the RecipientInfo kari
   choice is used in the AuthenticatedData.  When using 1-Pass ECMQV,
   the AuthenticatedData originatorInfo field MAY include the
   certificate(s) for the EC public key(s) used in the formation of the
   pairwise key.  ECC certificates are discussed in Section 5.

4.1.1. Fields of the KeyAgreeRecipientInfo

The AuthenticatedData KeyAgreeRecipientInfo fields are used in the same manner as the fields for the corresponding EnvelopedData KeyAgreeRecipientInfo fields of Section 3.2.1 of this document.

4.1.2. Actions of the Sending Agent

The sending agent uses the same actions as for EnvelopedData with 1-Pass ECMQV, as specified in Section 3.2.2 of this document. In a single message, if there are multiple layers for a recipient, then the ephemeral public key can be reused by the originator for that recipient in each of the different layers.

4.1.3. Actions of the Receiving Agent

The receiving agent uses the same actions as for EnvelopedData with 1-Pass ECMQV, as specified in Section 3.2.3 of this document.

4.2. AuthEnvelopedData Using 1-Pass ECMQV

This section describes how to use the 1-Pass ECMQV key agreement algorithm with AuthEnvelopedData. ECMQV is method C(1, 2, ECC MQV) from [SP800-56A]. When using ECMQV with AuthEnvelopedData, the fields of AuthEnvelopedData are as in [CMS-AUTHENV]. As 1-Pass ECMQV is a key agreement algorithm, the RecipientInfo kari choice is used. When using 1-Pass ECMQV, the AuthEnvelopedData originatorInfo field MAY include the certificate(s) for the EC public key used in the formation of the pairwise key. ECC certificates are discussed in Section 5.

4.2.1. Fields of the KeyAgreeRecipientInfo

The AuthEnvelopedData KeyAgreeRecipientInfo fields are used in the same manner as the fields for the corresponding EnvelopedData KeyAgreeRecipientInfo fields of Section 3.2.1 of this document.
Top   ToC   RFC5753 - Page 13

4.2.2. Actions of the Sending Agent

The sending agent uses the same actions as for EnvelopedData with 1-Pass ECMQV, as specified in Section 3.2.2 of this document. In a single message, if there are multiple layers for a recipient, then the ephemeral public key can be reused by the originator for that recipient in each of the different layers.

4.2.3. Actions of the Receiving Agent

The receiving agent uses the same actions as for EnvelopedData with 1-Pass ECMQV, as specified in Section 3.2.3 of this document.

5. Certificates Using ECC

Internet X.509 certificates [PKI] can be used in conjunction with this specification to distribute agents' public keys. The use of ECC algorithms and keys within X.509 certificates is specified in [PKI-ALG].

6. SMIMECapabilities Attribute and ECC

A sending agent MAY announce to receiving agents that it supports one or more of the ECC algorithms specified in this document by using the SMIMECapabilities signed attribute [MSG] in either a signed message or a certificate [CERTCAP]. The SMIMECapabilities attribute value indicates support for one of the ECDSA signature algorithms in a SEQUENCE with the capabilityID field containing the object identifier ecdsa-with-SHA1 with NULL parameters and ecdsa-with-SHA* (where * is 224, 256, 384, or 512) with absent parameters. The DER encodings are: ecdsa-with-SHA1: 30 0b 06 07 2a 86 48 ce 3d 04 01 05 00 ecdsa-with-SHA224: 30 0a 06 08 2a 86 48 ce 3d 04 03 01 ecdsa-with-SHA256: 30 0a 06 08 2a 86 48 ce 3d 04 03 02 ecdsa-with-SHA384: 30 0a 06 08 2a 86 48 ce 3d 04 03 03 ecdsa-with-SHA512: 30 0a 06 08 2a 86 48 ce 3d 04 03 04 NOTE: The SMIMECapabilities attribute indicates that parameters for ECDSA with SHA-1 are NULL; however, the parameters are absent when used to generate a digital signature.
Top   ToC   RFC5753 - Page 14
   The SMIMECapabilities attribute value indicates support for

      a)  the standard ECDH key agreement algorithm,
      b)  the cofactor ECDH key agreement algorithm, or
      c)  the 1-Pass ECMQV key agreement algorithm and

   is a SEQUENCE with the capabilityID field containing the object
   identifier

      a)  dhSinglePass-stdDH-sha*kdf-scheme,
      b)  dhSinglePass-cofactorDH-sha*kdf-scheme, or
      c)  mqvSinglePass-sha*kdf-scheme

   respectively (where * is 1, 224, 256, 384, or 512) with the
   parameters present.  The parameters indicate the supported key-
   encryption algorithm with the KeyWrapAlgorithm algorithm identifier.

   The DER encodings that indicate capabilities are as follows (KA is
   key agreement, KDF is key derivation function, and Wrap is key wrap
   algorithm):

      KA=ECDH standard KDF=SHA-1 Wrap=Triple-DES

        30 1c 06 09 2b 81 05 10 86 48 3f 00 02 30 0f 06 0b 2a 86 48 86
        f7 0d 01 09 10 03 06 05 00

      KA=ECDH standard KDF=SHA-224 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0B 00 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECDH standard KDF=SHA-256 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0B 01 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECDH standard KDF=SHA-384 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0B 02 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECDH standard KDF=SHA-512 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0B 03 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06
Top   ToC   RFC5753 - Page 15
      KA=ECDH standard KDF=SHA-1 Wrap=AES-128

        30 18 06 09 2b 81 05 10 86 48 3f 00 02 30 0b 06 09 60 86 48 01
        65 03 04 01 05

      KA=ECDH standard KDF=SHA-224 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0B 00 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECDH standard KDF=SHA-256 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0B 01 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECDH standard KDF=SHA-384 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0B 02 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECDH standard KDF=SHA-512 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0B 03 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECDH standard KDF=SHA-1 Wrap=AES-192

        30 18 06 09 2b 81 05 10 86 48 3f 00 02 30 0b 06 09 60 86 48 01
        65 03 04 01 19

      KA=ECDH standard KDF=SHA-224 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0B 00 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECDH standard KDF=SHA-256 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0B 01 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECDH standard KDF=SHA-384 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0B 02 30 0b 06 09 60 86 48 01 65 03 04
        01 19
Top   ToC   RFC5753 - Page 16
      KA=ECDH standard KDF=SHA-512 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0B 03 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECDH standard KDF=SHA-1 Wrap=AES-256

        30 18 06 09 2b 81 05 10 86 48 3f 00 02 30 0b 06 09 60 86 48 01
        65 03 04 01 2D

      KA=ECDH standard KDF=SHA-224 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0B 00 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

      KA=ECDH standard KDF=SHA-256 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0B 01 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

      KA=ECDH standard KDF=SHA-384 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0B 02 30 0b 06 09 60 86 48 01 65 03 04
        01 2D 05 00

      KA=ECDH standard KDF=SHA-512 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0B 03 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

      KA=ECDH cofactor KDF=SHA-1 Wrap=Triple-DES

        30 1c 06 09 2b 81 05 10 86 48 3f 00 03 30 0f 06 0b 2a 86 48 86
        f7 0d 01 09 10 03 06 05 00

      KA=ECDH cofactor KDF=SHA-224 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0E 00 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECDH cofactor KDF=SHA-256 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0E 01 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06
Top   ToC   RFC5753 - Page 17
      KA=ECDH cofactor KDF=SHA-384 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0E 02 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECDH cofactor KDF=SHA-512 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0E 03 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECDH cofactor KDF=SHA-1 Wrap=AES-128

        30 18 06 09 2b 81 05 10 86 48 3f 00 03 30 0b 06 09 60 86 48 01
        65 03 04 01 05

      KA=ECDH cofactor KDF=SHA-224 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0E 00 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECDH cofactor KDF=SHA-256 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0E 01 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECDH cofactor KDF=SHA-384 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0E 02 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECDH cofactor KDF=SHA-512 Wrap=AES-128

        30 17 06 06 2b 81 04 01 0E 03 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECDH cofactor KDF=SHA-1 Wrap=AES-192

        30 18 06 09 2b 81 05 10 86 48 3f 00 03 30 0b 06 09 60 86 48 01
        65 03 04 01 19

      KA=ECDH cofactor KDF=SHA-224 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0E 00 30 0b 06 09 60 86 48 01 65 03 04
        01 19
Top   ToC   RFC5753 - Page 18
      KA=ECDH cofactor KDF=SHA-256 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0E 01 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECDH cofactor KDF=SHA-384 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0E 02 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECDH cofactor KDF=SHA-512 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0E 03 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECDH cofactor KDF=SHA-1 Wrap=AES-256

        30 15 06 09 2b 81 05 10 86 48 3f 00 03 30 0b 06 09 60 86 48 01
        65 03 04 01 2D

      KA=ECDH cofactor KDF=SHA-224 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0E 00 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

      KA=ECDH cofactor KDF=SHA-256 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0E 01 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

      KA=ECDH cofactor KDF=SHA-384 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0E 02 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

      KA=ECDH cofactor KDF=SHA-512 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0E 03 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

      KA=ECMQV 1-Pass KDF=SHA-1 Wrap=Triple-DES

        30 1c 06 09 2b 81 05 10 86 48 3f 00 10 30 0f 06 0b 2a 86 48 86
        f7 0d 01 09 10 03 06 05 00
Top   ToC   RFC5753 - Page 19
      KA=ECMQV 1-Pass KDF=SHA-224 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0F 00 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECMQV 1-Pass KDF=SHA-256 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0F 01 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECMQV 1-Pass KDF=SHA-384 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0F 02 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECMQV 1-Pass KDF=SHA-512 Wrap=Triple-DES

        30 17 06 06 2b 81 04 01 0F 03 30 0d 06 0b 2a 86 48 86 f7 0d 01
        09 10 03 06

      KA=ECMQV 1-Pass KDF=SHA-1 Wrap=AES-128

        30 18 06 09 2b 81 05 10 86 48 3f 00 10 30 0b 06 09 60 86 48 01
        65 03 04 01 05

      KA=ECMQV 1-Pass KDF=SHA-224 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0F 00 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECMQV 1-Pass KDF=SHA-256 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0F 01 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECMQV 1-Pass KDF=SHA-384 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0F 02 30 0b 06 09 60 86 48 01 65 03 04
        01 05

      KA=ECMQV 1-Pass KDF=SHA-512 Wrap=AES-128

        30 15 06 06 2b 81 04 01 0F 03 30 0b 06 09 60 86 48 01 65 03 04
        01 05
Top   ToC   RFC5753 - Page 20
      KA=ECMQV 1-Pass KDF=SHA-1 Wrap=AES-192

        30 18 06 09 2b 81 05 10 86 48 3f 00 10 30 0b 06 09 60 86 48 01
        65 03 04 01 19

      KA=ECMQV 1-Pass KDF=SHA-224 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0F 00 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECMQV 1-Pass KDF=SHA-256 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0F 01 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECMQV 1-Pass KDF=SHA-384 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0F 02 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECMQV 1-Pass KDF=SHA-512 Wrap=AES-192

        30 15 06 06 2b 81 04 01 0F 03 30 0b 06 09 60 86 48 01 65 03 04
        01 19

      KA=ECMQV 1-Pass KDF=SHA-1 Wrap=AES-256

        30 18 06 09 2b 81 05 10 86 48 3f 00 10 30 0b 06 09 60 86 48 01
        65 03 04 01 2D

      KA=ECMQV 1-Pass KDF=SHA-224 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0F 00 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

      KA=ECMQV 1-Pass KDF=SHA-256 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0F 01 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

      KA=ECMQV 1-Pass KDF=SHA-384 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0F 02 30 0b 06 09 60 86 48 01 65 03 04
        01 2D
Top   ToC   RFC5753 - Page 21
      KA=ECMQV 1-Pass KDF=SHA-512 Wrap=AES-256

        30 15 06 06 2b 81 04 01 0F 03 30 0b 06 09 60 86 48 01 65 03 04
        01 2D

   NOTE: The S/MIME Capabilities for the supported AES content-
   encryption key sizes are defined in [CMS-AES].

   NOTE: The S/MIME Capabilities for the supported MAC algorithms are
   defined in [CMS-ASN].

7. ASN.1 Syntax

The ASN.1 syntax [X.680], [X.681], [X.682], [X.683] used in this document is gathered in this section for reference purposes.

7.1. Algorithm Identifiers

This section provides the object identifiers for the algorithms used in this document along with any associated parameters.

7.1.1. Digest Algorithms

Digest algorithm object identifiers are used in the SignedData digestAlgorithms and digestAlgorithm fields and the AuthenticatedData digestAlgorithm field. The digest algorithms used in this document are SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512. The object identifiers and parameters associated with these algorithms are found in [CMS-ALG] and [CMS-SHA2].

7.1.2. Originator Public Key

The KeyAgreeRecipientInfo originator field uses the following object identifier to indicate an elliptic curve public key: id-ecPublicKey OBJECT IDENTIFIER ::= { ansi-x9-62 keyType(2) 1 } where ansi-x9-62 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) 10045 } When the object identifier id-ecPublicKey is used here with an algorithm identifier, the associated parameters MUST be either absent or ECParameters. Implementations MUST accept id-ecPublicKey with absent and ECParameters parameters. If ECParameters is present, its
Top   ToC   RFC5753 - Page 22
   value MUST match the recipient's ECParameters.  Implementations
   SHOULD generate absent parameters for the id-ecPublicKey object
   identifier in the KeyAgreeRecipientInfo originator field.

   [CMS-ECC] indicated the parameters were NULL.  Support for this
   legacy form is OPTIONAL.

7.1.3. Signature Algorithms

Signature algorithm identifiers are used in the SignedData signatureAlgorithm and signature fields. The signature algorithms used in this document are ECDSA with SHA-1, ECDSA with SHA-224, ECDSA with SHA-256, ECDSA with SHA-384, and ECDSA with SHA-512. The object identifiers and parameters associated with these algorithms are found in [PKI-ALG]. [CMS-ECC] indicated the parameters were NULL. Support for this legacy form is OPTIONAL.

7.1.4. Key Agreement Algorithms

Key agreement algorithms are used in EnvelopedData, AuthenticatedData, and AuthEnvelopedData in the KeyAgreeRecipientInfo keyEncryptionAlgorithm field. The following object identifiers indicate the key agreement algorithms used in this document [SP800-56A], [SEC1]: dhSinglePass-stdDH-sha1kdf-scheme OBJECT IDENTIFIER ::= { x9-63-scheme 2 } dhSinglePass-stdDH-sha224kdf-scheme OBJECT IDENTIFIER ::= { secg-scheme 11 0 } dhSinglePass-stdDH-sha256kdf-scheme OBJECT IDENTIFIER ::= { secg-scheme 11 1 } dhSinglePass-stdDH-sha384kdf-scheme OBJECT IDENTIFIER ::= { secg-scheme 11 2 } dhSinglePass-stdDH-sha512kdf-scheme OBJECT IDENTIFIER ::= { secg-scheme 11 3 } dhSinglePass-cofactorDH-sha1kdf-scheme OBJECT IDENTIFIER ::= { x9-63-scheme 3 } dhSinglePass-cofactorDH-sha224kdf-scheme OBJECT IDENTIFIER ::= { secg-scheme 14 0 }
Top   ToC   RFC5753 - Page 23
      dhSinglePass-cofactorDH-sha256kdf-scheme OBJECT IDENTIFIER ::= {
        secg-scheme 14 1 }

      dhSinglePass-cofactorDH-sha384kdf-scheme OBJECT IDENTIFIER ::= {
        secg-scheme 14 2 }

      dhSinglePass-cofactorDH-sha512kdf-scheme OBJECT IDENTIFIER ::= {
        secg-scheme 14 3 }

      mqvSinglePass-sha1kdf-scheme OBJECT IDENTIFIER ::= {
        x9-63-scheme 16 }

      mqvSinglePass-sha224kdf-scheme OBJECT IDENTIFIER ::= {
        secg-scheme 15 0 }

      mqvSinglePass-sha256kdf-scheme OBJECT IDENTIFIER ::= {
        secg-scheme 15 1 }

      mqvSinglePass-sha384kdf-scheme OBJECT IDENTIFIER ::= {
        secg-scheme 15 2 }

      mqvSinglePass-sha512kdf-scheme OBJECT IDENTIFIER ::= {
        secg-scheme 15 3 }

   where

      x9-63-scheme OBJECT IDENTIFIER ::= {
        iso(1) identified-organization(3) tc68(133) country(16)
        x9(840) x9-63(63) schemes(0) }

   and

      secg-scheme OBJECT IDENTIFIER ::= {
        iso(1) identified-organization(3) certicom(132) schemes(1) }

   When the object identifiers are used here within an algorithm
   identifier, the associated parameters field contains KeyWrapAlgorithm
   to indicate the key wrap algorithm and any associated parameters.

7.1.5. Key Wrap Algorithms

Key wrap algorithms are used as part of the parameters in the key agreement algorithm. The key wrap algorithms used in this document are Triple-DES, AES-128, AES-192, and AES-256. The object identifiers and parameters for these algorithms are found in [CMS-ALG] and [CMS-AES].
Top   ToC   RFC5753 - Page 24

7.1.6. Content Encryption Algorithms

Content encryption algorithms are used in EnvelopedData and AuthEnvelopedData in the EncryptedContentInfo contentEncryptionAlgorithm field. The content encryption algorithms used with EnvelopedData in this document are 3-Key Triple DES in CBC mode, AES-128 in CBC mode, AES-192 in CBC mode, and AES-256 in CBC mode. The object identifiers and parameters associated with these algorithms are found in [CMS-ALG] and [CMS-AES]. The content encryption algorithms used with AuthEnvelopedData in this document are AES-128 in CCM mode, AES-192 in CCM mode, AES-256 in CCM mode, AES-128 in GCM mode, AES-192 in GCM mode, and AES-256 in GCM mode. The object identifiers and parameters associated with these algorithms are found in [CMS-AESCG].

7.1.7. Message Authentication Code Algorithms

Message authentication code algorithms are used in AuthenticatedData in the macAlgorithm field. The message authentication code algorithms used in this document are HMAC with SHA-1, HMAC with SHA-224, HMAC with SHA-256, HMAC with SHA-384, and HMAC with SHA-512. The object identifiers and parameters associated with these algorithms are found in [CMS-ALG] and [HMAC-SHA2]. NOTE: [HMAC-SHA2] defines the object identifiers for HMAC with SHA-224, HMAC with SHA-256, HMAC with SHA-384, and HMAC with SHA-512, but there is no ASN.1 module from which to import these object identifiers. Therefore, the object identifiers for these algorithms are included in the ASN.1 modules defined in Appendix A.

7.1.8. Key Derivation Algorithm

The KDF used in this document is as specified in Section 3.6.1 of [SEC1]. The hash algorithm is identified in the key agreement algorithm. For example, dhSinglePass-stdDH-sha256kdf-scheme uses the KDF from [SEC1] but uses SHA-256 instead of SHA-1.

7.2. Other Syntax

The following additional syntax is used here. When using ECDSA with SignedData, ECDSA signatures are encoded using the type: ECDSA-Sig-Value ::= SEQUENCE { r INTEGER, s INTEGER }
Top   ToC   RFC5753 - Page 25
   ECDSA-Sig-Value is specified in [PKI-ALG].  Within CMS, ECDSA-Sig-
   Value is DER-encoded and placed within a signature field of
   SignedData.

   When using ECDH and ECMQV with EnvelopedData, AuthenticatedData, and
   AuthEnvelopedData, ephemeral and static public keys are encoded using
   the type ECPoint.  Implementations MUST support uncompressed keys,
   MAY support compressed keys, and MUST NOT support hybrid keys.

      ECPoint ::= OCTET STRING

   When using ECMQV with EnvelopedData, AuthenticatedData, and
   AuthEnvelopedData, the sending agent's ephemeral public key and
   additional keying material are encoded using the type:

      MQVuserKeyingMaterial ::= SEQUENCE {
        ephemeralPublicKey      OriginatorPublicKey,
        addedukm            [0] EXPLICIT UserKeyingMaterial OPTIONAL  }

   The ECPoint syntax is used to represent the ephemeral public key and
   is placed in the ephemeralPublicKey publicKey field.  The additional
   user keying material is placed in the addedukm field.  Then the
   MQVuserKeyingMaterial value is DER-encoded and placed within the ukm
   field of EnvelopedData, AuthenticatedData, or AuthEnvelopedData.

   When using ECDH or ECMQV with EnvelopedData, AuthenticatedData, or
   AuthEnvelopedData, the key-encryption keys are derived by using the
   type:

      ECC-CMS-SharedInfo ::= SEQUENCE {
        keyInfo         AlgorithmIdentifier,
        entityUInfo [0] EXPLICIT OCTET STRING OPTIONAL,
        suppPubInfo [2] EXPLICIT OCTET STRING  }

   The fields of ECC-CMS-SharedInfo are as follows:

      keyInfo contains the object identifier of the key-encryption
      algorithm (used to wrap the CEK) and associated parameters.  In
      this specification, 3DES wrap has NULL parameters while the AES
      wraps have absent parameters.

      entityUInfo optionally contains additional keying material
      supplied by the sending agent.  When used with ECDH and CMS, the
      entityUInfo field contains the octet string ukm.  When used with
      ECMQV and CMS, the entityUInfo contains the octet string addedukm
      (encoded in MQVuserKeyingMaterial).
Top   ToC   RFC5753 - Page 26
      suppPubInfo contains the length of the generated KEK, in bits,
      represented as a 32-bit number, as in [CMS-DH] and [CMS-AES].
      (For example, for AES-256 it would be 00 00 01 00.)

   Within CMS, ECC-CMS-SharedInfo is DER-encoded and used as input to
   the key derivation function, as specified in Section 3.6.1 of [SEC1].

   NOTE: ECC-CMS-SharedInfo differs from the OtherInfo specified in
   [CMS-DH].  Here, a counter value is not included in the keyInfo field
   because the key derivation function specified in Section 3.6.1 of
   [SEC1] ensures that sufficient keying data is provided.

8. Recommended Algorithms and Elliptic Curves

It is RECOMMENDED that implementations of this specification support SignedData and EnvelopedData. Support for AuthenticatedData and AuthEnvelopedData is OPTIONAL. In order to encourage interoperability, implementations SHOULD use the elliptic curve domain parameters specified by [PKI-ALG]. Implementations that support SignedData with ECDSA: - MUST support ECDSA with SHA-256; and - MAY support ECDSA with SHA-1, ECDSA with SHA-224, ECDSA with SHA-384, and ECDSA with SHA-512; other digital signature algorithms MAY also be supported. When using ECDSA, to promote interoperability it is RECOMMENDED that the P-192, P-224, and P-256 curves be used with SHA-256; the P-384 curve be used with SHA-384; and the P-521 curve be used with SHA-512. If EnvelopedData is supported, then ephemeral-static ECDH standard primitive MUST be supported. Support for ephemeral-static ECDH co- factor is OPTIONAL, and support for 1-Pass ECMQV is also OPTIONAL. Implementations that support EnvelopedData with the ephemeral-static ECDH standard primitive: - MUST support the dhSinglePass-stdDH-sha256kdf-scheme key agreement algorithm, the id-aes128-wrap key wrap algorithm, and the id-aes128-cbc content encryption algorithm; and
Top   ToC   RFC5753 - Page 27
      - MAY support the dhSinglePass-stdDH-sha1kdf-scheme, dhSinglePass-
        stdDH-sha224kdf-scheme, dhSinglePass-stdDH-sha384kdf-scheme, and
        dhSinglePass-stdDH-sha512kdf-scheme key agreement algorithms;
        the id-alg-CMS3DESwrap, id-aes192-wrap, and id-aes256-wrap key
        wrap algorithms; and the des-ede3-cbc, id-aes192-cbc, and id-
        aes256-cbc content encryption algorithms; other algorithms MAY
        also be supported.

   Implementations that support EnvelopedData with the ephemeral-static
   ECDH cofactor primitive:

      - MUST support the dhSinglePass-cofactorDH-sha256kdf-scheme key
        agreement algorithm, the id-aes128-wrap key wrap algorithm, and
        the id-aes128-cbc content encryption algorithm; and

      - MAY support the dhSinglePass-cofactorDH-sha1kdf-scheme,
        dhSinglePass-cofactorDH-sha224kdf-scheme, dhSinglePass-
        cofactorDH-sha384kdf-scheme, and dhSinglePass-cofactorDH-
        sha512kdf-scheme key agreement; the id-alg-CMS3DESwrap, id-
        aes192-wrap, and id-aes256-wrap key wrap algorithms; and the
        des-ede3-cbc, id-aes192-cbc, and id-aes256-cbc content
        encryption algorithms; other algorithms MAY also be supported.

   Implementations that support EnvelopedData with 1-Pass ECMQV:

      - MUST support the mqvSinglePass-sha256kdf-scheme key agreement
        algorithm, the id-aes128-wrap key wrap algorithm, and the id-
        aes128-cbc content encryption algorithm; and

      - MAY support the mqvSinglePass-sha1kdf-scheme, mqvSinglePass-
        sha224kdf-scheme, mqvSinglePass-sha384kdf-scheme, and
        mqvSinglePass-sha512kdf-scheme key agreement algorithms; the id-
        alg-CMS3DESwrap, id-aes192-wrap, and id-aes256-wrap key wrap
        algorithms; and the des-ede3-cbc, id-aes192-cbc, and id-
        aes256-cbc content encryption algorithms; other algorithms MAY
        also be supported.

   Implementations that support AuthenticatedData with 1-Pass ECMQV:

      - MUST support the mqvSinglePass-sha256kdf-scheme key agreement,
        the id-aes128-wrap key wrap, the id-sha256 message digest, and
        id-hmacWithSHA256 message authentication code algorithms; and

      - MAY support the mqvSinglePass-sha1kdf-scheme, mqvSinglePass-
        sha224kdf-scheme, mqvSinglePass-sha384kdf-scheme, mqvSinglePass-
        sha512kdf-scheme key agreement algorithms; the id-alg-
        CMS3DESwrap, id-aes192-wrap, and id-aes256-wrap key wrap
        algorithms; the id-sha1, id-sha224, id-sha384, and id-sha512,
Top   ToC   RFC5753 - Page 28
        message digest algorithms; and the hmac-SHA1, id-hmacWithSHA224,
        id-hmacWithSHA384, and id-hmacWithSHA512 message authentication
        code algorithms; other algorithms MAY also be supported.

   Implementations that support AuthEnvelopedData with 1-Pass ECMQV:

      - MUST support the mqvSinglePass-sha256kdf-scheme key agreement,
        the id-aes128-wrap key wrap, and the id-aes128-ccm
        authenticated-content encryption; and

      - MAY support the mqvSinglePass-sha1kdf-scheme, mqvSinglePass-
        sha224kdf-scheme, mqvSinglePass-sha384kdf-scheme, and
        mqvSinglePass-sha512kdf-scheme key agreement algorithms; the id-
        alg-CMS3DESwrap, id-aes192-wrap, and id-aes256-wrap key wrap
        algorithms; and the id-aes192-ccm, id-aes256-ccm, id-aes128-gcm,
        id-aes192-gcm, and id-aes256-ccm authenticated-content
        encryption algorithms; other algorithms MAY also be supported.

9. Security Considerations

Cryptographic algorithms will be broken or weakened over time. Implementers and users need to check that the cryptographic algorithms listed in this document continue to provide the expected level of security. The IETF from time to time may issue documents dealing with the current state of the art. Cryptographic algorithms rely on random numbers. See [RANDOM] for guidance on generation of random numbers. Receiving agents that validate signatures and sending agents that encrypt messages need to be cautious of cryptographic processing usage when validating signatures and encrypting messages using keys larger than those mandated in this specification. An attacker could send keys and/or certificates with keys that would result in excessive cryptographic processing, for example, keys larger than those mandated in this specification, which could swamp the processing element. Agents that use such keys without first validating the certificate to a trust anchor are advised to have some sort of cryptographic resource management system to prevent such attacks. Using secret keys of an appropriate size is crucial to the security of a Diffie-Hellman exchange. For elliptic curve groups, the size of the secret key must be equal to the size of n (the order of the group generated by the point g). Using larger secret keys provides absolutely no additional security, and using smaller secret keys is likely to result in dramatically less security. (See [SP800-56A] for more information on selecting secret keys.)
Top   ToC   RFC5753 - Page 29
   This specification is based on [CMS], [CMS-AES], [CMS-AESCG],
   [CMS-ALG], [CMS-AUTHENV], [CMS-DH], [CMS-SHA2], [FIPS180-3],
   [FIPS186-3], and [HMAC-SHA2], and the appropriate security
   considerations of those documents apply.

   In addition, implementers of AuthenticatedData and AuthEnvelopedData
   should be aware of the concerns expressed in [BON] when using
   AuthenticatedData and AuthEnvelopedData to send messages to more than
   one recipient.  Also, users of MQV should be aware of the
   vulnerability described in [K].

   When implementing EnvelopedData, AuthenticatedData, and
   AuthEnvelopedData, there are five algorithm-related choices that need
   to be made:

      1) What is the public key size?
      2) What is the KDF?
      3) What is the key wrap algorithm?
      4) What is the content encryption algorithm?
      5) What is the curve?

   Consideration must be given to the strength of the security provided
   by each of these choices.  Security algorithm strength is measured in
   bits, where bits is measured in equivalence to a symmetric cipher
   algorithm.  Thus, a strong symmetric cipher algorithm with a key of X
   bits is said to provide X bits of security.  For other algorithms,
   the key size is mapped to an equivalent symmetric cipher strength.
   It is recommended that the bits of security provided by each are
   roughly equivalent.  The following table provides comparable minimum
   bits of security [SP800-57] for the ECDH/ECMQV key sizes, KDFs, key
   wrapping algorithms, and content encryption algorithms.  It also
   lists curves [PKI-ALG] for the key sizes.
Top   ToC   RFC5753 - Page 30
   Minimum  | ECDH or  | Key        | Key      | Content     | Curves
   Bits of  | ECMQV    | Derivation | Wrap     | Encryption  |
   Security | Key Size | Function   | Alg.     | Alg.        |
   ---------+----------+------------+----------+-------------+----------
   80       | 160-223  | SHA-1      | 3DES     | 3DES CBC    | sect163k1
            |          | SHA-224    | AES-128  | AES-128 CBC | secp163r2
            |          | SHA-256    | AES-192  | AES-192 CBC | secp192r1
            |          | SHA-384    | AES-256  | AES-256 CBC |
            |          | SHA-512    |          |             |
   ---------+----------+------------+----------+-------------+---------
   112      | 224-255  | SHA-1      | 3DES     | 3DES CBC    | secp224r1
            |          | SHA-224    | AES-128  | AES-128 CBC | sect233k1
            |          | SHA-256    | AES-192  | AES-192 CBC | sect233r1
            |          | SHA-384    | AES-256  | AES-256 CBC |
            |          | SHA-512    |          |             |
   ---------+----------+------------+----------+-------------+---------
   128      | 256-383  | SHA-1      | AES-128  | AES-128 CBC | secp256r1
            |          | SHA-224    | AES-192  | AES-192 CBC | sect283k1
            |          | SHA-256    | AES-256  | AES-256 CBC | sect283r1
            |          | SHA-384    |          |             |
            |          | SHA-512    |          |             |
   ---------+----------+------------+----------+-------------+---------
   192      | 384-511  | SHA-224    | AES-192  | AES-192 CBC | secp384r1
            |          | SHA-256    | AES-256  | AES-256 CBC | sect409k1
            |          | SHA-384    |          |             | sect409r1
            |          | SHA-512    |          |             |
   ---------+----------+------------+----------+-------------+---------
   256      | 512+     | SHA-256    | AES-256  | AES-256 CBC | secp521r1
            |          | SHA-384    |          |             | sect571k1
            |          | SHA-512    |          |             | sect571r1
   ---------+----------+------------+----------+-------------+---------
Top   ToC   RFC5753 - Page 31
   To promote interoperability, the following choices are RECOMMENDED:

   Minimum  | ECDH or  | Key        | Key      | Content     | Curve
   Bits of  | ECMQV    | Derivation | Wrap     | Encryption  |
   Security | Key Size | Function   | Alg.     | Alg.        |
   ---------+----------+------------+----------+-------------+----------
   80       | 192      | SHA-256    | 3DES     | 3DES CBC    | secp192r1
   ---------+----------+------------+----------+-------------+----------
   112      | 224      | SHA-256    | 3DES     | 3DES CBC    | secp224r1
   ---------+----------+------------+----------+-------------+----------
   128      | 256      | SHA-256    | AES-128  | AES-128 CBC | secp256r1
   ---------+----------+------------+----------+-------------+----------
   192      | 384      | SHA-384    | AES-256  | AES-256 CBC | secp384r1
   ---------+----------+------------+----------+-------------+----------
   256      | 512+     | SHA-512    | AES-256  | AES-256 CBC | secp521r1
   ---------+----------+------------+----------+-------------+----------

   When implementing SignedData, there are three algorithm-related
   choices that need to be made:

      1) What is the public key size?
      2) What is the hash algorithm?
      3) What is the curve?

   Consideration must be given to the bits of security provided by each
   of these choices.  Security is measured in bits, where a strong
   symmetric cipher with a key of X bits is said to provide X bits of
   security.  It is recommended that the bits of security provided by
   each choice are roughly equivalent.  The following table provides
   comparable minimum bits of security [SP800-57] for the ECDSA key
   sizes and message digest algorithms.  It also lists curves [PKI-ALG]
   for the key sizes.
Top   ToC   RFC5753 - Page 32
   Minimum  | ECDSA    | Message   | Curve
   Bits of  | Key Size | Digest    |
   Security |          | Algorithm |
   ---------+----------+-----------+-----------
   80       | 160-223  | SHA-1     | sect163k1
            |          | SHA-224   | secp163r2
            |          | SHA-256   | secp192r1
            |          | SHA-384   |
            |          | SHA-512   |
   ---------+----------+-----------+-----------
   112      | 224-255  | SHA-224   | secp224r1
            |          | SHA-256   | sect233k1
            |          | SHA-384   | sect233r1
            |          | SHA-512   |
   ---------+----------+-----------+-----------
   128      | 256-383  | SHA-256   | secp256r1
            |          | SHA-384   | sect283k1
            |          | SHA-512   | sect283r1
   ---------+----------+-----------+-----------
   192      | 384-511  | SHA-384   | secp384r1
            |          | SHA-512   | sect409k1
            |          |           | sect409r1
   ---------+----------+-----------+-----------
   256      | 512+     | SHA-512   | secp521r1
            |          |           | sect571k1
            |          |           | sect571r1
   ---------+----------+-----------+-----------

   To promote interoperability, the following choices are RECOMMENDED:

   Minimum  | ECDSA    | Message   | Curve
   Bits of  | Key Size | Digest    |
   Security |          | Algorithm |
   ---------+----------+-----------+-----------
   80       | 192      | SHA-256   | sect192r1
   ---------+----------+-----------+-----------
   112      | 224      | SHA-256   | secp224r1
   ---------+----------+-----------+-----------
   128      | 256      | SHA-256   | secp256r1
   ---------+----------+-----------+-----------
   192      | 384      | SHA-384   | secp384r1
   ---------+----------+-----------+-----------
   256      | 512+     | SHA-512   | secp521r1
   ---------+----------+-----------+-----------
Top   ToC   RFC5753 - Page 33

10. IANA Considerations

This document makes extensive use of object identifiers to register originator public key types and algorithms. The algorithm object identifiers are registered in the ANSI X9.62, ANSI X9.63, NIST, RSA, and SECG arcs. Additionally, object identifiers are used to identify the ASN.1 modules found in Appendix A (there are two). These are defined by the SMIME WG Registrar in an arc delegated by RSA to the SMIME Working Group: iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) modules(0). No action by IANA is necessary for this document or any anticipated updates.


(page 33 continued on part 3)

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