( mixed x509cert, int purpose [, array cainfo [, string untrustedfile]] )
Returns TRUE if the certificate can be used for the intended purpose, FALSE if it cannot, or -1 on error.
openssl_x509_checkpurpose() examines the certificate specified by x509cert to see if it can be used for the purpose specified by purpose.
cainfo should be an array of trusted CA files/dirs as described in Certificate Verification. It defaults to an
untrustedfile, if specified, is the name of a PEM encoded file holding certificates that can be used to help verify the certificate, although no trust in placed in the
certificates that come from that file.
Table 1. openssl_x509_checkpurpose() purposes
||Can the certificate be used for the client side of an SSL connection?
||Can the certificate be used for the server side of an SSL connection?
||Can the cert be used for Netscape SSL server?
||Can the cert be used to sign S/MIME email?
||Can the cert be used to encrypt S/MIME email?
||Can the cert be used to sign a certificate revocation list (CRL)?
||Can the cert be used for Any/All purposes?
These options are not bitfields - you may specify one only!