int gnutls_x509_crt_set_version(gnutls_x509_crt_t crt, unsigned int version);
a certificate of type gnutls_x509_crt_t
unsigned int version
holds the version number. For X.509v1 certificates must be 1.
This function will set the version of the certificate. This must
be one for X.509 version 1, and so on. Plain certificates without
extensions must have version set to one.
To create well-formed certificates, you must specify version 3 if
you use any certificate extensions. Extensions are created by
functions such as gnutls_x509_crt_set_subject_alt_name()
On success, GNUTLS_E_SUCCESS is returned, otherwise a
negative error value.