X509Data

X509Data is a data structure defined in the ASN.1 (Abstract Syntax Notation One) standard, commonly used in public key infrastructure (PKI) and digital security protocols. It serves as a container for X.509 certificates and certificate revocation lists (CRLs), allowing them to be encoded in a standardized binary or text format. The structure is widely employed in cryptographic systems, including SSL/TLS, S/MIME, and PKCS (Public Key Cryptography Standards) frameworks.

An X509Data object can encapsulate one or more X.509 certificates, each containing public key information, issuer details, subject identification, validity periods, and digital signatures. It may also include CRLs, which list revoked certificates to ensure their continued validity can be verified. The ASN.1 definition of X509Data allows flexibility in how certificates and CRLs are organized, making it adaptable for various security applications.

In practice, X509Data is often serialized using Base64 encoding for transport over text-based protocols, such as HTTP or SMTP. This encoding ensures compatibility with systems that rely on ASCII-based communication. The structure is particularly useful in scenarios where certificates or CRLs need to be embedded within other data formats, such as XML or JSON, to facilitate secure authentication and verification processes.

X509Data is standardized under ITU-T X.509 and is referenced in multiple security protocols, including RFC 5280 (Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List Profile). Its role in PKI ensures reliable identity verification and secure communication across distributed systems.