Overview
ISO/IEC 24824-4:2021 specifies an updated Cryptographic Message Syntax (CMS) ASN.1 module and extensions that modernize CMS for current implementations. It enhances the CMS protocol (IETF RFC 5652) by adding signcryption techniques (from ISO/IEC 29150) and providing ASN.1 definitions that conform to the latest ASN.1 edition and work with all standardized ASN.1 encoding rules. The standard defines new types (for example, SigncryptedData) and modes for combining signing and encryption in a single, efficient operation.
Key topics and technical requirements
- ASN.1 module conformance: provides updated ASN.1 modules (see Annex A) compatible with the current ASN.1 syntax and with all standard encoding rules (BER/DER/CER/…).
- Signcryption support: introduces a SigncryptedData type and multiple signcryption modes:
- signcrypted-content
- signcrypted-attributes
- signcrypted-components
- signcrypted-envelope
- CMS content model: continues to use CMS content types (data, signedData, envelopedData, digestedData, encryptedData, authenticatedData) each identified by object identifiers (OIDs).
- Certificate and revocation handling: SigncryptedData structures may include certificate sets and CRLs to support recipient validation.
- Key management and quantum-aware options: includes clauses on other key management techniques (constructive key management, database encryption key management) and dedicated material on quantum safe SignedData signatures, timestamping, and tokenized parts.
- Reusable ASN.1 modules: annexes include reusable modules such as CMSSigncryption, CMSObjectIdentifiers, and various PKIX-related modules to integrate with PKI and protocol stacks.
Applications and who should use it
ISO/IEC 24824-4 is intended for implementers and architects who need standardized, interoperable message security:
- Security architects and PKI designers integrating CMS-based messaging (S/MIME, secure email, document exchange).
- Protocol and application developers implementing ASN.1-based CMS with signcryption to achieve simultaneous authentication, integrity and confidentiality.
- Product vendors of secure messaging, secure storage, and cryptographic libraries who require ASN.1 modules compatible with current encoding rules.
- Compliance and standards teams aligning products with international cryptographic message standards and future-proofing against post-quantum concerns.
Related standards
This standard is essential when you need a modern ASN.1-based CMS with integrated signcryption and broad encoding-rule compatibility for secure, interoperable message processing.