# Cryptographic Message Syntax `rasn-cms` is an implementation of the data types defined in IETF [RFC 4108], [RFC 5083], [RFC 5084], and [RFC 5652]. Also known as Cryptographic Message Syntax (CMS) or PKCS#7. This does not provide an implementation of a CMS generator or validator, instead `rasn-cms` provides an implementation of the underlying data types used to decode and encode the CMS structures from/to DER or BER. [RFC 4108]: https://datatracker.ietf.org/doc/html/rfc4108 [RFC 5083]: https://datatracker.ietf.org/doc/html/rfc5083 [RFC 5084]: https://datatracker.ietf.org/doc/html/rfc5084 [RFC 5652]: https://datatracker.ietf.org/doc/html/rfc5652