EC_GROUP *EC_GROUP_new_from_ecparameters(const ECPARAMETERS *params)
{
int ok = 0, tmp;
- EC_GROUP *ret = NULL;
+ EC_GROUP *ret = NULL, *dup = NULL;
BIGNUM *p = NULL, *a = NULL, *b = NULL;
EC_POINT *point = NULL;
long field_bits;
+ int curve_name = NID_undef;
+ BN_CTX *ctx = NULL;
if (!params->fieldID || !params->fieldID->fieldType ||
!params->fieldID->p.ptr) {
goto err;
}
+ /*
+ * Check if the explicit parameters group just created matches one of the
+ * built-in curves.
+ *
+ * We create a copy of the group just built, so that we can remove optional
+ * fields for the lookup: we do this to avoid the possibility that one of
+ * the optional parameters is used to force the library into using a less
+ * performant and less secure EC_METHOD instead of the specialized one.
+ * In any case, `seed` is not really used in any computation, while a
+ * cofactor different from the one in the built-in table is just
+ * mathematically wrong anyway and should not be used.
+ */
+ if ((ctx = BN_CTX_new()) == NULL) {
+ ECerr(EC_F_EC_GROUP_NEW_FROM_ECPARAMETERS, ERR_R_BN_LIB);
+ goto err;
+ }
+ if ((dup = EC_GROUP_dup(ret)) == NULL
+ || EC_GROUP_set_seed(dup, NULL, 0) != 1
+ || !EC_GROUP_set_generator(dup, point, a, NULL)) {
+ ECerr(EC_F_EC_GROUP_NEW_FROM_ECPARAMETERS, ERR_R_EC_LIB);
+ goto err;
+ }
+ if ((curve_name = ec_curve_nid_from_params(dup, ctx)) != NID_undef) {
+ /*
+ * The input explicit parameters successfully matched one of the
+ * built-in curves: often for built-in curves we have specialized
+ * methods with better performance and hardening.
+ *
+ * In this case we replace the `EC_GROUP` created through explicit
+ * parameters with one created from a named group.
+ */
+ EC_GROUP *named_group = NULL;
+
+#ifndef OPENSSL_NO_EC_NISTP_64_GCC_128
+ /*
+ * NID_wap_wsg_idm_ecid_wtls12 and NID_secp224r1 are both aliases for
+ * the same curve, we prefer the SECP nid when matching explicit
+ * parameters as that is associated with a specialized EC_METHOD.
+ */
+ if (curve_name == NID_wap_wsg_idm_ecid_wtls12)
+ curve_name = NID_secp224r1;
+#endif /* !def(OPENSSL_NO_EC_NISTP_64_GCC_128) */
+
+ if ((named_group = EC_GROUP_new_by_curve_name(curve_name)) == NULL) {
+ ECerr(EC_F_EC_GROUP_NEW_FROM_ECPARAMETERS, ERR_R_EC_LIB);
+ goto err;
+ }
+ EC_GROUP_free(ret);
+ ret = named_group;
+
+ /*
+ * Set the flag so that EC_GROUPs created from explicit parameters are
+ * serialized using explicit parameters by default.
+ */
+ EC_GROUP_set_asn1_flag(ret, OPENSSL_EC_EXPLICIT_CURVE);
+ }
+
ok = 1;
err:
if (!ok) {
- EC_GROUP_clear_free(ret);
+ EC_GROUP_free(ret);
ret = NULL;
}
+ EC_GROUP_free(dup);
BN_free(p);
BN_free(a);
BN_free(b);
EC_POINT_free(point);
- return (ret);
+
+ BN_CTX_free(ctx);
+
+ return ret;
}
EC_GROUP *EC_GROUP_new_from_ecpkparameters(const ECPKPARAMETERS *params)
}
if (a) {
- EC_GROUP_clear_free(*a);
+ EC_GROUP_free(*a);
*a = group;
}
ret = *a;
if (priv_key->parameters) {
- EC_GROUP_clear_free(ret->group);
+ EC_GROUP_free(ret->group);
ret->group = EC_GROUP_new_from_ecpkparameters(priv_key->parameters);
}
}
return NID_undef;
}
+
+static ossl_inline
+int ec_group_get_curve(const EC_GROUP *group, BIGNUM *p, BIGNUM *a,
+ BIGNUM *b, BN_CTX *ctx)
+{
+ int field_nid;
+
+ field_nid = EC_METHOD_get_field_type(EC_GROUP_method_of(group));
+
+#ifndef OPENSSL_NO_EC2M
+ if (field_nid == NID_X9_62_characteristic_two_field) {
+ return EC_GROUP_get_curve_GF2m(group, p, a, b, ctx);
+ } else
+#endif /* !def(OPENSSL_NO_EC2M) */
+ if (field_nid == NID_X9_62_prime_field) {
+ return EC_GROUP_get_curve_GFp(group, p, a, b, ctx);
+ } else {
+ /* this should never happen */
+ return 0;
+ }
+}
+
+static ossl_inline
+int ec_point_get_affine_coordinates(const EC_GROUP *group,
+ const EC_POINT *point, BIGNUM *x,
+ BIGNUM *y, BN_CTX *ctx)
+{
+ int field_nid;
+
+ field_nid = EC_METHOD_get_field_type(EC_GROUP_method_of(group));
+
+#ifndef OPENSSL_NO_EC2M
+ if (field_nid == NID_X9_62_characteristic_two_field) {
+ return EC_POINT_get_affine_coordinates_GFp(group, point, x, y, ctx);
+ } else
+#endif /* !def(OPENSSL_NO_EC2M) */
+ if (field_nid == NID_X9_62_prime_field) {
+ return EC_POINT_get_affine_coordinates_GF2m(group, point, x, y, ctx);
+ } else {
+ /* this should never happen */
+ return 0;
+ }
+}
+
+#define NUM_BN_FIELDS 6
+/*
+ * Validates EC domain parameter data for known named curves.
+ * This can be used when a curve is loaded explicitly (without a curve
+ * name) or to validate that domain parameters have not been modified.
+ *
+ * Returns: The nid associated with the found named curve, or NID_undef
+ * if not found. If there was an error it returns -1.
+ */
+int ec_curve_nid_from_params(const EC_GROUP *group, BN_CTX *ctx)
+{
+ int ret = -1, nid, len, field_type, param_len;
+ size_t i, seed_len;
+ const unsigned char *seed, *params_seed, *params;
+ unsigned char *param_bytes = NULL;
+ const EC_CURVE_DATA *data;
+ const EC_POINT *generator = NULL;
+ const EC_METHOD *meth;
+ const BIGNUM *cofactor = NULL;
+ /* An array of BIGNUMs for (p, a, b, x, y, order) */
+ BIGNUM *bn[NUM_BN_FIELDS] = {NULL, NULL, NULL, NULL, NULL, NULL};
+
+ meth = EC_GROUP_method_of(group);
+ if (meth == NULL)
+ return -1;
+ /* Use the optional named curve nid as a search field */
+ nid = EC_GROUP_get_curve_name(group);
+ field_type = EC_METHOD_get_field_type(meth);
+ seed_len = EC_GROUP_get_seed_len(group);
+ seed = EC_GROUP_get0_seed(group);
+ cofactor = EC_GROUP_get0_cofactor(group);
+
+ BN_CTX_start(ctx);
+
+ /*
+ * The built-in curves contains data fields (p, a, b, x, y, order) that are
+ * all zero-padded to be the same size. The size of the padding is
+ * determined by either the number of bytes in the field modulus (p) or the
+ * EC group order, whichever is larger.
+ */
+ param_len = BN_num_bytes(group->order);
+ len = BN_num_bytes(group->field);
+ if (len > param_len)
+ param_len = len;
+
+ /* Allocate space to store the padded data for (p, a, b, x, y, order) */
+ param_bytes = OPENSSL_malloc(param_len * NUM_BN_FIELDS);
+ if (param_bytes == NULL)
+ goto end;
+
+ /* Create the bignums */
+ for (i = 0; i < NUM_BN_FIELDS; ++i) {
+ if ((bn[i] = BN_CTX_get(ctx)) == NULL)
+ goto end;
+ }
+ /*
+ * Fill in the bn array with the same values as the internal curves
+ * i.e. the values are p, a, b, x, y, order.
+ */
+ /* Get p, a & b */
+ if (!(ec_group_get_curve(group, bn[0], bn[1], bn[2], ctx)
+ && ((generator = EC_GROUP_get0_generator(group)) != NULL)
+ /* Get x & y */
+ && ec_point_get_affine_coordinates(group, generator, bn[3], bn[4], ctx)
+ /* Get order */
+ && EC_GROUP_get_order(group, bn[5], ctx)))
+ goto end;
+
+ /*
+ * Convert the bignum array to bytes that are joined together to form
+ * a single buffer that contains data for all fields.
+ * (p, a, b, x, y, order) are all zero padded to be the same size.
+ */
+ for (i = 0; i < NUM_BN_FIELDS; ++i) {
+ if (BN_bn2binpad(bn[i], ¶m_bytes[i*param_len], param_len) <= 0)
+ goto end;
+ }
+
+ for (i = 0; i < curve_list_length; i++) {
+ const ec_list_element curve = curve_list[i];
+
+ data = curve.data;
+ /* Get the raw order byte data */
+ params_seed = (const unsigned char *)(data + 1); /* skip header */
+ params = params_seed + data->seed_len;
+
+ /* Look for unique fields in the fixed curve data */
+ if (data->field_type == field_type
+ && param_len == data->param_len
+ && (nid <= 0 || nid == curve.nid)
+ /* check the optional cofactor (ignore if its zero) */
+ && (BN_is_zero(cofactor)
+ || BN_is_word(cofactor, (const BN_ULONG)curve.data->cofactor))
+ /* Check the optional seed (ignore if its not set) */
+ && (data->seed_len == 0 || seed_len == 0
+ || ((size_t)data->seed_len == seed_len
+ && memcmp(params_seed, seed, seed_len) == 0))
+ /* Check that the groups params match the built-in curve params */
+ && memcmp(param_bytes, params, param_len * NUM_BN_FIELDS)
+ == 0) {
+ ret = curve.nid;
+ goto end;
+ }
+ }
+ /* Gets here if the group was not found */
+ ret = NID_undef;
+end:
+ OPENSSL_free(param_bytes);
+ BN_CTX_end(ctx);
+ return ret;
+}
projects / oweals / openssl.git / commitdiff