(PHP 4 >= 4.0.6, PHP 5)
openssl_x509_parse — Parse an X509 certificate and return the information as an array
openssl_x509_parse() returns information about the supplied x509cert, including fields such as subject name, issuer name, purposes, valid from and valid to dates etc.
shortnames controls how the data is indexed in the array - if shortnames is TRUE (the default) then fields will be indexed with the short name form, otherwise, the long name form will be used - e.g.: CN is the shortname form of commonName.
The structure of the returned data is (deliberately) not yet documented, as it is still subject to change.