A null terminated string with the PEM header (eg. CERTIFICATE)
const gnutls_datum_t * b64_data
contain the encoded data
unsigned char * result
the place where decoded data will be copied
size_t * result_size
holds the size of the result
DESCRIPTION
This function will decode the given encoded data. If the header
given is non null this function will search for "-----BEGIN header"
and decode only this part. Otherwise it will decode the first PEM
packet found.
RETURNS
On success GNUTLS_E_SUCCESS (0) is returned,
GNUTLS_E_SHORT_MEMORY_BUFFER is returned if the buffer given is
not long enough, or 0 on success.