Explicitly pass group generator to mul_double_nonct() from EC_POINT_mul().

EC_POINT_mul() has a complex multi-use interface - there are effectively
three different ways it will behave, depending on which arguments are NULL.
In the case where we compute g_scalar * generator + p_scalar * point, the
mul_double_nonct() function pointer is called, however only g_scalar,
p_scalar and point are passed - it is expected that the lower level
implementation (in this case ec_wnaf_mul()) will use the generator from
the group.

Change mul_double_nonct(), ec_mul_double_nonct() and ec_wnaf_mul() so that
they take scalar1, point1, scalar2 and point2. This removes all knowledge
of g_scalar and the generator from the multiplication code, keeping it
limited to EC_POINT_mul(). While here also consistently pass scalar then
point, rather than a mix of scalar/point and point/scalar.

ok tb@

1 files changed, 5 insertions, 4 deletions

diff --git a/src/lib/libcrypto/ec/ecp_methods.c b/src/lib/libcrypto/ec/ecp_methods.c
index 544c2be4d4..ced85ceb1e 100644
--- a/src/lib/libcrypto/ec/ecp_methods.c
+++ b/src/lib/libcrypto/ec/ecp_methods.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ecp_methods.c,v 1.44 2025/03/09 15:33:35 tb Exp $ */
+/* $OpenBSD: ecp_methods.c,v 1.45 2025/03/24 13:07:04 jsing Exp $ */
 /* Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
  * for the OpenSSL project.
  * Includes code written by Bodo Moeller for the OpenSSL project.
@@ -1194,10 +1194,11 @@ ec_mul_single_ct(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
 }
 
 static int
-ec_mul_double_nonct(const EC_GROUP *group, EC_POINT *r, const BIGNUM *g_scalar,
-    const BIGNUM *p_scalar, const EC_POINT *point, BN_CTX *ctx)
+ec_mul_double_nonct(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar1,
+    const EC_POINT *point1, const BIGNUM *scalar2, const EC_POINT *point2,
+    BN_CTX *ctx)
 {
-        return ec_wnaf_mul(group, r, g_scalar, point, p_scalar, ctx);
+        return ec_wnaf_mul(group, r, scalar1, point1, scalar2, point2, ctx);
 }
 
 static int