Cryptographic Message Syntax
{{Short description|International standard}}
{{third-party |date=April 2024}}
The Cryptographic Message Syntax (CMS) is the IETF's standard for cryptographically protected messages. It can be used by cryptographic schemes and protocols to digitally sign, digest, authenticate or encrypt any form of digital data.
CMS is based on the syntax of PKCS #7, which in turn is based on the Privacy-Enhanced Mail standard. The newest version of CMS ({{As of|2024|lc=on}}) is specified in {{IETF RFC|5652}} (but also see {{IETF RFC|5911}} for updated ASN.1 modules conforming to ASN.1 2002 and {{IETF RFC|8933}} and {{IETF RFC|9629}} for updates to the standard).
The architecture of CMS is built around certificate-based key management, such as the profile defined by the PKIX working group. CMS is used as the key cryptographic component of many other cryptographic standards, such as S/MIME, PKCS #12 and the {{IETF RFC|3161}} digital timestamping protocol.
OpenSSL is open source software that can encrypt, decrypt, sign and verify, compress and uncompress CMS documents, using the openssl-cms command.
Norms and Standards
Cryptographic Message Syntax (CMS) is regularly updated to address evolving security needs and emerging cryptographic algorithms.
- {{IETF RFC|8933}} (Update to the Cryptographic Message Syntax (CMS) for Algorithm Identifier Protection)
- {{IETF RFC|5652}} (Cryptographic Message Syntax (CMS), in use)
- {{IETF RFC|3852}} (Cryptographic Message Syntax (CMS), obsolete)
- {{IETF RFC|3369}} (Cryptographic Message Syntax (CMS), obsolete)
- {{IETF RFC|2630}} (Cryptographic Message Syntax, obsolete)
- {{IETF RFC|6268}} (New ASN.1 Modules for Cryptographic Message Syntax (CMS) and S/MIME, in use)
- {{IETF RFC|5911}} (New ASN.1 Modules for Cryptographic Message Syntax (CMS) and S/MIME, updated)
- {{IETF RFC|5753}} (Using Elliptic Curve Cryptography with CMS, in use)
- {{IETF RFC|3278}} (Use of Elliptic Curve Cryptography (ECC) Algorithms in Cryptographic Message Syntax (CMS), obsolete)
- {{IETF RFC|5084}} (Using AES-CCM and AES-GCM Authenticated Encryption in the Cryptographic Message Syntax (CMS), in use)
- {{IETF RFC|9629}} (Using Key Encapsulation Mechanism (KEM) Algorithms in the Cryptographic Message Syntax (CMS), in use)