/* Create a new point option. NBITS gives the size in bits of one
coordinate; it is only used to pre-allocate some resources and
might also be passed as 0 to use a default value. */
mpi_point_t
gcry_mpi_point_new (unsigned int nbits)
{
mpi_point_t p;
(void)nbits; /* Currently not used. */
p = gcry_xmalloc (sizeof *p);
_gcry_mpi_point_init (p);
return p;
}
/*
* Return a copy of a curve object.
*/
elliptic_curve_t
_gcry_ecc_curve_copy (elliptic_curve_t E)
{
elliptic_curve_t R;
R.model = E.model;
R.dialect = E.dialect;
R.name = E.name;
R.p = mpi_copy (E.p);
R.a = mpi_copy (E.a);
R.b = mpi_copy (E.b);
_gcry_mpi_point_init (&R.G);
point_set (&R.G, &E.G);
R.n = mpi_copy (E.n);
return R;
}
/* Return the name matching the parameters in PKEY. This works only
with curves described by the Weierstrass equation. */
const char *
_gcry_ecc_get_curve (gcry_sexp_t keyparms, int iterator, unsigned int *r_nbits)
{
gpg_err_code_t rc;
const char *result = NULL;
elliptic_curve_t E;
gcry_mpi_t mpi_g = NULL;
gcry_mpi_t tmp = NULL;
int idx;
memset (&E, 0, sizeof E);
if (r_nbits)
*r_nbits = 0;
if (!keyparms)
{
idx = iterator;
if (idx >= 0 && idx < DIM (domain_parms))
{
result = domain_parms[idx].desc;
if (r_nbits)
*r_nbits = domain_parms[idx].nbits;
}
return result;
}
/*
* Extract the curve parameters..
*/
rc = gpg_err_code (sexp_extract_param (keyparms, NULL, "-pabgn",
&E.p, &E.a, &E.b, &mpi_g, &E.n,
NULL));
if (rc == GPG_ERR_NO_OBJ)
{
/* This might be the second use case of checking whether a
specific curve given by name is supported. */
gcry_sexp_t l1;
char *name;
l1 = sexp_find_token (keyparms, "curve", 5);
if (!l1)
goto leave; /* No curve name parameter. */
name = sexp_nth_string (l1, 1);
sexp_release (l1);
if (!name)
goto leave; /* Name missing or out of core. */
idx = find_domain_parms_idx (name);
xfree (name);
if (idx >= 0) /* Curve found. */
{
result = domain_parms[idx].desc;
if (r_nbits)
*r_nbits = domain_parms[idx].nbits;
}
return result;
}
if (rc)
goto leave;
if (mpi_g)
{
_gcry_mpi_point_init (&E.G);
if (_gcry_ecc_os2ec (&E.G, mpi_g))
goto leave;
}
for (idx = 0; domain_parms[idx].desc; idx++)
{
mpi_free (tmp);
tmp = scanval (domain_parms[idx].p);
if (!mpi_cmp (tmp, E.p))
{
mpi_free (tmp);
tmp = scanval (domain_parms[idx].a);
if (!mpi_cmp (tmp, E.a))
{
mpi_free (tmp);
tmp = scanval (domain_parms[idx].b);
if (!mpi_cmp (tmp, E.b))
{
mpi_free (tmp);
tmp = scanval (domain_parms[idx].n);
if (!mpi_cmp (tmp, E.n))
{
mpi_free (tmp);
tmp = scanval (domain_parms[idx].g_x);
if (!mpi_cmp (tmp, E.G.x))
{
mpi_free (tmp);
tmp = scanval (domain_parms[idx].g_y);
if (!mpi_cmp (tmp, E.G.y))
{
result = domain_parms[idx].desc;
if (r_nbits)
*r_nbits = domain_parms[idx].nbits;
goto leave;
}
}
}
}
}
}
}
leave:
_gcry_mpi_release (tmp);
_gcry_mpi_release (E.p);
_gcry_mpi_release (E.a);
_gcry_mpi_release (E.b);
_gcry_mpi_release (mpi_g);
_gcry_mpi_point_free_parts (&E.G);
_gcry_mpi_release (E.n);
return result;
}