Are there other digital certificate formats than X.509? Hi I am a little new to security, but in researching digital certificates it seems the only format people describe is X.509.

Are there other formats? If so what are they and where can I find information on them?
Although x.509 is the standard for PKIs with CAs, different certificate formats have been defined for the other 2 major PKI approaches:


SPKI has defined its own certificate
format , still (forever?) in
draft status.
Web-of-Trust models usually use the OpenPGP certificate format defined in RFC2440


RFC4212 "Alternative Certificate Formats for the Public-Key Infrastructure Using X.509 (PKIX) Certificate Management Protocols" may also be of interest.