@deftypefun {int} {gnutls_x509_crt_set_serial} (gnutls_x509_crt_t @var{cert}, const void * @var{serial}, size_t @var{serial_size})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{serial}: The serial number

@var{serial_size}: Holds the size of the serial field.

This function will set the X.509 certificate's serial number.
While the serial number is an integer, it is often handled
as an opaque field by several CAs. For this reason this function
accepts any kind of data as a serial number. To be consistent
with the X.509/PKIX specifications the provided  @code{serial} should be 
a big-endian positive number (i.e. it's leftmost bit should be zero).

The size of the serial is restricted to 20 bytes maximum by RFC5280.
This function allows writing more than 20 bytes but the generated
certificates in that case may be rejected by other implementations.

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