Restore EC_GROUP_new_by_curve_name and EC_GROUP_set_generator.
Having a different API for this case than upstream is more trouble than is
worth it. This is sad since the new API avoids incomplete EC_GROUPs at least,
but I don't believe supporting this pair of functions will be significantly
more complex than supporting EC_GROUP_new_arbitrary even when we have static
EC_GROUPs.
For now, keep both sets of APIs around, but we'll be able to remove the scar
tissue once Conscrypt's complex dependencies are resolved.
Make the restored EC_GROUP_set_generator somewhat simpler than before by
removing the ability to call it multiple times and with some parameters set to
NULL. Keep the test.
Change-Id: I64e3f6a742678411904cb15c0ad15d56cdae4a73
Reviewed-on: https://boringssl-review.googlesource.com/7432
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/include/openssl/ec.h b/include/openssl/ec.h
index 23196fa..143aa96 100644
--- a/include/openssl/ec.h
+++ b/include/openssl/ec.h
@@ -289,13 +289,37 @@
/* Deprecated functions. */
-/* EC_GROUP_new_arbitrary creates a new, arbitrary elliptic curve group based on
- * the equation y² = x³ + a·x + b. The generator is set to (gx, gy) which must
- * have the given order and cofactor. It returns the new group or NULL on error.
+/* EC_GROUP_new_curve_GFp creates a new, arbitrary elliptic curve group based
+ * on the equation y² = x³ + a·x + b. It returns the new group or NULL on
+ * error.
+ *
+ * This new group has no generator. It is an error to use a generator-less group
+ * with any functions except for |EC_GROUP_free|, |EC_POINT_new|,
+ * |EC_POINT_set_affine_coordinates_GFp|, and |EC_GROUP_set_generator|.
*
* |EC_GROUP|s returned by this function will always compare as unequal via
* |EC_GROUP_cmp| (even to themselves). |EC_GROUP_get_curve_name| will always
- * return |NID_undef|. */
+ * return |NID_undef|.
+ *
+ * Avoid using arbitrary curves and use |EC_GROUP_new_by_curve_name| instead. */
+OPENSSL_EXPORT EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p,
+ const BIGNUM *a,
+ const BIGNUM *b, BN_CTX *ctx);
+
+/* EC_GROUP_set_generator sets the generator for |group| to |generator|, which
+ * must have the given order and cofactor. It may only be used with |EC_GROUP|
+ * objects returned by |EC_GROUP_new_curve_GFp| and may only be used once on
+ * each group. */
+OPENSSL_EXPORT int EC_GROUP_set_generator(EC_GROUP *group,
+ const EC_POINT *generator,
+ const BIGNUM *order,
+ const BIGNUM *cofactor);
+
+/* EC_GROUP_new_arbitrary calls |EC_GROUP_new_curve_GFp| and
+ * |EC_GROUP_set_generator|.
+ *
+ * TODO(davidben): Remove this once
+ * https://android-review.googlesource.com/#/c/207990/ has cycled in. */
OPENSSL_EXPORT EC_GROUP *EC_GROUP_new_arbitrary(
const BIGNUM *p, const BIGNUM *a, const BIGNUM *b, const BIGNUM *gx,
const BIGNUM *gy, const BIGNUM *order, const BIGNUM *cofactor);
