( mixed x509cert [, bool shortnames] )
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.