line 146

ecc-eddsa.c

/* Make sure that the opaque MPI VALUE is in compact EdDSA format.
   This function updates MPI if needed.  */
gpg_err_code_t
_gcry_ecc_eddsa_ensure_compact (gcry_mpi_t value, unsigned int nbits)
{
  gpg_err_code_t rc;
  const unsigned char *buf;
  unsigned int rawmpilen;
  gcry_mpi_t x, y;
  unsigned char *enc;
  unsigned int enclen;

  if (!mpi_is_opaque (value))
    return GPG_ERR_INV_OBJ;
  buf = mpi_get_opaque (value, &rawmpilen);
  if (!buf)
    return GPG_ERR_INV_OBJ;
  rawmpilen = (rawmpilen + 7)/8;

  if (rawmpilen > 1 && (rawmpilen%2))
    {
      if (buf[0] == 0x04)
        {
          /* Buffer is in SEC1 uncompressed format.  Extract y and
             compress.  */
          rc = _gcry_mpi_scan (&x, GCRYMPI_FMT_STD,
                               buf+1, (rawmpilen-1)/2, NULL);