There is a set of de facto cryptographic message standards called Public Key Cryptography Standards (PKCS) which were originally
developed and are still maintained by RSA Laboratories. See the
RSA website for more information.
The standards that are most relevant to PKI are:
- PKCS #7, Cryptographic Message Syntax Standard. A general syntax for data to which cryptography can be applied, such as digital
signatures and encryption. It also provides a syntax for disseminating certificates or certificate revocation lists (CRLs).
- PKCS #10, Certification Request Syntax Standard. Provides a format for a request for a certificate.
- PKCS #12, Personal Information Exchange Syntax Standard. Primarily provides a format for storing keys or a certificate in
a file.