@deftypefun {int} {gnutls_x509_crl_get_crt_serial} (gnutls_x509_crl_t @var{crl}, unsigned @var{indx}, unsigned char * @var{serial}, size_t * @var{serial_size}, time_t * @var{t})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{indx}: the index of the certificate to extract (starting from 0)

@var{serial}: where the serial number will be copied

@var{serial_size}: initially holds the size of serial

@var{t}: if non null, will hold the time this certificate was revoked

This function will retrieve the serial number of the specified, by
the index, revoked certificate.

Note that this function will have performance issues in large sequences
of revoked certificates. In that case use @code{gnutls_x509_crl_iter_crt_serial()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun