Prepare removal accessors for Jprojective coordinates

That the BN-driven EC code uses Jacobian projective coordinates as an
optimization is an implementation detail. As such this should never have
leaked out of the library as part of the public API. No consumer should
ever care and if they do they're doing it wrong. The only port that cares
is one of those stupid little perl modules that expose all the things and
transform terrible OpenSSL regress tests into similarly horrible Perl.

In practice, only affine coordinates matter (perhaps in compressed form).

This prunes two more function pointers from EC_GROUP and prepares the
removal of the field_set_to_one() method which is now only used in
ec_points_make_affine().

ok jsing sthen

3 files changed, 16 insertions, 150 deletions

diff --git a/src/lib/libcrypto/ec/ec_lib.c b/src/lib/libcrypto/ec/ec_lib.c
index d961ad0ee4..03c6f3aa90 100644
--- a/src/lib/libcrypto/ec/ec_lib.c
+++ b/src/lib/libcrypto/ec/ec_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_lib.c,v 1.94 2025/01/05 16:07:08 tb Exp $ */
+/* $OpenBSD: ec_lib.c,v 1.95 2025/01/06 10:56:46 tb Exp $ */
 /*
  * Originally written by Bodo Moeller for the OpenSSL project.
  */
@@ -908,78 +908,11 @@ EC_POINT_set_to_infinity(const EC_GROUP *group, EC_POINT *point)
 LCRYPTO_ALIAS(EC_POINT_set_to_infinity);
 
 int
-EC_POINT_set_Jprojective_coordinates(const EC_GROUP *group, EC_POINT *point,
-    const BIGNUM *x, const BIGNUM *y, const BIGNUM *z, BN_CTX *ctx_in)
-{
-        BN_CTX *ctx;
-        int ret = 0;
-
-        if ((ctx = ctx_in) == NULL)
-                ctx = BN_CTX_new();
-        if (ctx == NULL)
-                goto err;
-
-        if (group->meth->point_set_Jprojective_coordinates == NULL) {
-                ECerror(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
-                goto err;
-        }
-        if (group->meth != point->meth) {
-                ECerror(EC_R_INCOMPATIBLE_OBJECTS);
-                goto err;
-        }
-        if (!group->meth->point_set_Jprojective_coordinates(group, point,
-            x, y, z, ctx))
-                goto err;
-
-        if (EC_POINT_is_on_curve(group, point, ctx) <= 0) {
-                ECerror(EC_R_POINT_IS_NOT_ON_CURVE);
-                goto err;
-        }
-
-        ret = 1;
-
- err:
-        if (ctx != ctx_in)
-                BN_CTX_free(ctx);
-
-        return ret;
-}
-
-int
-EC_POINT_get_Jprojective_coordinates(const EC_GROUP *group,
-    const EC_POINT *point, BIGNUM *x, BIGNUM *y, BIGNUM *z, BN_CTX *ctx_in)
-{
-        BN_CTX *ctx;
-        int ret = 0;
-
-        if ((ctx = ctx_in) == NULL)
-                ctx = BN_CTX_new();
-        if (ctx == NULL)
-                goto err;
-
-        if (group->meth->point_get_Jprojective_coordinates == NULL) {
-                ECerror(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
-                goto err;
-        }
-        if (group->meth != point->meth) {
-                ECerror(EC_R_INCOMPATIBLE_OBJECTS);
-                goto err;
-        }
-        ret = group->meth->point_get_Jprojective_coordinates(group, point,
-            x, y, z, ctx);
-
- err:
-        if (ctx != ctx_in)
-                BN_CTX_free(ctx);
-
-        return ret;
-}
-
-int
 EC_POINT_set_Jprojective_coordinates_GFp(const EC_GROUP *group, EC_POINT *point,
     const BIGNUM *x, const BIGNUM *y, const BIGNUM *z, BN_CTX *ctx)
 {
-        return EC_POINT_set_Jprojective_coordinates(group, point, x, y, z, ctx);
+        ECerror(ERR_R_DISABLED);
+        return 0;
 }
 LCRYPTO_ALIAS(EC_POINT_set_Jprojective_coordinates_GFp);
 
@@ -987,7 +920,8 @@ int
 EC_POINT_get_Jprojective_coordinates_GFp(const EC_GROUP *group,
     const EC_POINT *point, BIGNUM *x, BIGNUM *y, BIGNUM *z, BN_CTX *ctx)
 {
-        return EC_POINT_get_Jprojective_coordinates(group, point, x, y, z, ctx);
+        ECerror(ERR_R_DISABLED);
+        return 0;
 }
 LCRYPTO_ALIAS(EC_POINT_get_Jprojective_coordinates_GFp);
 
diff --git a/src/lib/libcrypto/ec/ec_local.h b/src/lib/libcrypto/ec/ec_local.h
index 0d734351de..2bddaddd8a 100644
--- a/src/lib/libcrypto/ec/ec_local.h
+++ b/src/lib/libcrypto/ec/ec_local.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_local.h,v 1.46 2025/01/05 16:07:08 tb Exp $ */
+/* $OpenBSD: ec_local.h,v 1.47 2025/01/06 10:56:46 tb Exp $ */
 /*
  * Originally written by Bodo Moeller for the OpenSSL project.
  */
@@ -99,10 +99,6 @@ struct ec_method_st {
         int (*group_order_bits)(const EC_GROUP *);
         int (*group_check_discriminant)(const EC_GROUP *, BN_CTX *);
 
-        int (*point_set_Jprojective_coordinates)(const EC_GROUP *, EC_POINT *,
-            const BIGNUM *x, const BIGNUM *y, const BIGNUM *z, BN_CTX *);
-        int (*point_get_Jprojective_coordinates)(const EC_GROUP *,
-            const EC_POINT *, BIGNUM *x, BIGNUM *y, BIGNUM *z, BN_CTX *);
         int (*point_set_affine_coordinates)(const EC_GROUP *, EC_POINT *,
             const BIGNUM *x, const BIGNUM *y, BN_CTX *);
         int (*point_get_affine_coordinates)(const EC_GROUP *, const EC_POINT *,
@@ -277,11 +273,6 @@ int ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
 int ecdh_KDF_X9_63(unsigned char *out, size_t outlen, const unsigned char *Z,
     size_t Zlen, const unsigned char *sinfo, size_t sinfolen, const EVP_MD *md);
 
-int EC_POINT_set_Jprojective_coordinates(const EC_GROUP *group, EC_POINT *p,
-    const BIGNUM *x, const BIGNUM *y, const BIGNUM *z, BN_CTX *ctx);
-int EC_POINT_get_Jprojective_coordinates(const EC_GROUP *group,
-    const EC_POINT *p, BIGNUM *x, BIGNUM *y, BIGNUM *z, BN_CTX *ctx);
-
 int ec_group_is_builtin_curve(const EC_GROUP *group, int *out_nid);
 int ec_group_get_field_type(const EC_GROUP *group);
 
diff --git a/src/lib/libcrypto/ec/ecp_methods.c b/src/lib/libcrypto/ec/ecp_methods.c
index b2ecc7e17a..7bdeb351da 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 1.18 2025/01/05 16:07:08 tb Exp $ */
+/* $OpenBSD: ecp_methods.c,v 1.19 2025/01/06 10:56:46 tb 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.
@@ -124,23 +124,6 @@ ec_encode_scalar(const EC_GROUP *group, BIGNUM *bn, const BIGNUM *x, BN_CTX *ctx
 }
 
 static int
-ec_encode_z_coordinate(const EC_GROUP *group, BIGNUM *bn, int *is_one,
-    const BIGNUM *z, BN_CTX *ctx)
-{
-        if (!BN_nnmod(bn, z, group->p, ctx))
-                return 0;
-
-        *is_one = BN_is_one(bn);
-        if (*is_one && group->meth->field_set_to_one != NULL)
-                return group->meth->field_set_to_one(group, bn, ctx);
-
-        if (group->meth->field_encode != NULL)
-                return group->meth->field_encode(group, bn, bn, ctx);
-
-        return 1;
-}
-
-static int
 ec_group_set_curve(EC_GROUP *group,
     const BIGNUM *p, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
 {
@@ -262,48 +245,23 @@ ec_group_check_discriminant(const EC_GROUP *group, BN_CTX *ctx)
 }
 
 static int
-ec_set_Jprojective_coordinates(const EC_GROUP *group, EC_POINT *point,
-    const BIGNUM *x, const BIGNUM *y, const BIGNUM *z, BN_CTX *ctx)
+ec_point_set_affine_coordinates(const EC_GROUP *group, EC_POINT *point,
+    const BIGNUM *x, const BIGNUM *y, BN_CTX *ctx)
 {
         int ret = 0;
 
-        /*
-         * Setting individual coordinates allows the creation of bad points.
-         * EC_POINT_set_Jprojective_coordinates() checks at the API boundary.
-         */
-
-        if (x != NULL) {
-                if (!ec_encode_scalar(group, point->X, x, ctx))
-                        goto err;
-        }
-        if (y != NULL) {
-                if (!ec_encode_scalar(group, point->Y, y, ctx))
-                        goto err;
-        }
-        if (z != NULL) {
-                if (!ec_encode_z_coordinate(group, point->Z, &point->Z_is_one,
-                    z, ctx))
-                        goto err;
+        if (x == NULL || y == NULL) {
+                ECerror(ERR_R_PASSED_NULL_PARAMETER);
+                goto err;
         }
 
-        ret = 1;
-
- err:
-        return ret;
-}
-
-static int
-ec_get_Jprojective_coordinates(const EC_GROUP *group, const EC_POINT *point,
-    BIGNUM *x, BIGNUM *y, BIGNUM *z, BN_CTX *ctx)
-{
-        int ret = 0;
-
-        if (!ec_decode_scalar(group, x, point->X, ctx))
+        if (!ec_encode_scalar(group, point->X, x, ctx))
                 goto err;
-        if (!ec_decode_scalar(group, y, point->Y, ctx))
+        if (!ec_encode_scalar(group, point->Y, y, ctx))
                 goto err;
-        if (!ec_decode_scalar(group, z, point->Z, ctx))
+        if (!ec_encode_scalar(group, point->Z, BN_value_one(), ctx))
                 goto err;
+        point->Z_is_one = 1;
 
         ret = 1;
 
@@ -312,19 +270,6 @@ ec_get_Jprojective_coordinates(const EC_GROUP *group, const EC_POINT *point,
 }
 
 static int
-ec_point_set_affine_coordinates(const EC_GROUP *group, EC_POINT *point,
-    const BIGNUM *x, const BIGNUM *y, BN_CTX *ctx)
-{
-        if (x == NULL || y == NULL) {
-                /* unlike for projective coordinates, we do not tolerate this */
-                ECerror(ERR_R_PASSED_NULL_PARAMETER);
-                return 0;
-        }
-        return EC_POINT_set_Jprojective_coordinates(group, point, x, y,
-            BN_value_one(), ctx);
-}
-
-static int
 ec_point_get_affine_coordinates(const EC_GROUP *group, const EC_POINT *point,
     BIGNUM *x, BIGNUM *y, BN_CTX *ctx)
 {
@@ -1652,8 +1597,6 @@ static const EC_METHOD ec_GFp_simple_method = {
         .group_get_degree = ec_group_get_degree,
         .group_order_bits = ec_group_simple_order_bits,
         .group_check_discriminant = ec_group_check_discriminant,
-        .point_set_Jprojective_coordinates = ec_set_Jprojective_coordinates,
-        .point_get_Jprojective_coordinates = ec_get_Jprojective_coordinates,
         .point_set_affine_coordinates = ec_point_set_affine_coordinates,
         .point_get_affine_coordinates = ec_point_get_affine_coordinates,
         .point_set_compressed_coordinates = ec_set_compressed_coordinates,
@@ -1687,8 +1630,6 @@ static const EC_METHOD ec_GFp_mont_method = {
         .group_get_degree = ec_group_get_degree,
         .group_order_bits = ec_group_simple_order_bits,
         .group_check_discriminant = ec_group_check_discriminant,
-        .point_set_Jprojective_coordinates = ec_set_Jprojective_coordinates,
-        .point_get_Jprojective_coordinates = ec_get_Jprojective_coordinates,
         .point_set_affine_coordinates = ec_point_set_affine_coordinates,
         .point_get_affine_coordinates = ec_point_get_affine_coordinates,
         .point_set_compressed_coordinates = ec_set_compressed_coordinates,