/* Store the MPI NEWVALUE into the context EC under NAME. */
gpg_err_code_t
_gcry_ecc_set_mpi (const char *name, gcry_mpi_t newvalue, mpi_ec_t ec)
{
gpg_err_code_t rc = 0;
if (!*name)
;
else if (!strcmp (name, "p"))
{
mpi_free (ec->p);
ec->p = mpi_copy (newvalue);
_gcry_mpi_ec_get_reset (ec);
}
else if (!strcmp (name, "a"))
{
mpi_free (ec->a);
ec->a = mpi_copy (newvalue);
_gcry_mpi_ec_get_reset (ec);
}
else if (!strcmp (name, "b"))
{
mpi_free (ec->b);
ec->b = mpi_copy (newvalue);
}
else if (!strcmp (name, "n"))
{
mpi_free (ec->n);
ec->n = mpi_copy (newvalue);
}
else if (!strcmp (name, "h"))
{
mpi_free (ec->h);
ec->h = mpi_copy (newvalue);
}
else if (*name == 'q' && (!name[1] || name[1] == '@'))
{
if (newvalue)
{
if (!ec->Q)
ec->Q = mpi_point_new (0);
if (ec->dialect == ECC_DIALECT_ED25519)
rc = _gcry_ecc_eddsa_decodepoint (newvalue, ec, ec->Q, NULL, NULL);
else
rc = _gcry_ecc_os2ec (ec->Q, newvalue);
}
if (rc || !newvalue)
{
_gcry_mpi_point_release (ec->Q);
ec->Q = NULL;
}
/* Note: We assume that Q matches d and thus do not reset d. */
}
else if (!strcmp (name, "d"))
{
mpi_free (ec->d);
ec->d = mpi_copy (newvalue);
if (ec->d)
{
/* We need to reset the public key because it may not
anymore match. */
_gcry_mpi_point_release (ec->Q);
ec->Q = NULL;
}
}
else
rc = GPG_ERR_UNKNOWN_NAME;
return rc;
}
/* Helper to extract a point from key parameters. If no parameter
with NAME is found, the functions tries to find a non-encoded point
by appending ".x", ".y" and ".z" to NAME. ".z" is in this case
optional and defaults to 1. EC is the context which at this point
may not be fully initialized. */
static gpg_err_code_t
point_from_keyparam (gcry_mpi_point_t *r_a,
gcry_sexp_t keyparam, const char *name, mpi_ec_t ec)
{
gcry_err_code_t rc;
gcry_sexp_t l1;
gcry_mpi_point_t point;
l1 = sexp_find_token (keyparam, name, 0);
if (l1)
{
gcry_mpi_t a;
a = sexp_nth_mpi (l1, 1, GCRYMPI_FMT_OPAQUE);
sexp_release (l1);
if (!a)
return GPG_ERR_INV_OBJ;
point = mpi_point_new (0);
if (ec && ec->dialect == ECC_DIALECT_ED25519)
rc = _gcry_ecc_eddsa_decodepoint (a, ec, point, NULL, NULL);
else
rc = _gcry_ecc_os2ec (point, a);
mpi_free (a);
if (rc)
{
mpi_point_release (point);
return rc;
}
}
else
{
char *tmpname;
gcry_mpi_t x = NULL;
gcry_mpi_t y = NULL;
gcry_mpi_t z = NULL;
tmpname = xtrymalloc (strlen (name) + 2 + 1);
if (!tmpname)
return gpg_err_code_from_syserror ();
strcpy (stpcpy (tmpname, name), ".x");
rc = mpi_from_keyparam (&x, keyparam, tmpname);
if (rc)
{
xfree (tmpname);
return rc;
}
strcpy (stpcpy (tmpname, name), ".y");
rc = mpi_from_keyparam (&y, keyparam, tmpname);
if (rc)
{
mpi_free (x);
xfree (tmpname);
return rc;
}
strcpy (stpcpy (tmpname, name), ".z");
rc = mpi_from_keyparam (&z, keyparam, tmpname);
if (rc)
{
mpi_free (y);
mpi_free (x);
xfree (tmpname);
return rc;
}
if (!z)
z = mpi_set_ui (NULL, 1);
if (x && y)
point = mpi_point_snatch_set (NULL, x, y, z);
else
{
mpi_free (x);
mpi_free (y);
mpi_free (z);
point = NULL;
}
xfree (tmpname);
}
if (point)
*r_a = point;
return 0;
}
