/* Hash all multi precision integers of the key PK with the given
message digest context MD. */
static int
hash_mpibuf (cdk_pubkey_t pk, digest_hd_st * md, int usefpr)
{
byte buf[MAX_MPI_BYTES]; /* FIXME: do not use hardcoded length. */
size_t nbytes;
size_t i, npkey;
int err;
/* We have to differ between two modes for v3 keys. To form the
fingerprint, we hash the MPI values without the length prefix.
But if we calculate the hash for verifying/signing we use all data. */
npkey = cdk_pk_get_npkey (pk->pubkey_algo);
for (i = 0; i < npkey; i++)
{
nbytes = MAX_MPI_BYTES;
err = _gnutls_mpi_print_pgp (pk->mpi[i], buf, &nbytes);
if (err < 0)
return map_gnutls_error (err);
if (!usefpr || pk->version == 4)
_gnutls_hash (md, buf, nbytes);
else /* without the prefix. */
_gnutls_hash (md, buf + 2, nbytes - 2);
}
return 0;
}
static u16 checksum_mpi(bigint_t m)
{
byte buf[MAX_MPI_BYTES + 2];
size_t nread;
unsigned int i;
u16 chksum = 0;
if (!m)
return 0;
nread = DIM(buf);
if (_gnutls_mpi_print_pgp(m, buf, &nread) < 0)
return 0;
for (i = 0; i < nread; i++)
chksum += buf[i];
return chksum;
}
static int
write_mpi (cdk_stream_t out, bigint_t m)
{
byte buf[MAX_MPI_BYTES + 2];
size_t nbits, nread;
int err;
if (!out || !m)
return CDK_Inv_Value;
nbits = _gnutls_mpi_get_nbits (m);
if (nbits > MAX_MPI_BITS || nbits < 1)
return CDK_MPI_Error;
nread = MAX_MPI_BYTES + 2;
err = _gnutls_mpi_print_pgp (m, buf, &nread);
if (err < 0)
return map_gnutls_error (err);
return stream_write (out, buf, nread);
}
