-
- /* rh := X^3 */
- if (!group->meth->field_sqr(group, tmp1, &point->X, ctx)) goto err;
- if (!group->meth->field_mul(group, rh, tmp1, &point->X, ctx)) goto err;
-
- /* rh := rh + a*X^2 */
- if (!group->meth->field_mul(group, tmp1, tmp1, &group->a, ctx)) goto err;
- if (!BN_GF2m_add(rh, rh, tmp1)) goto err;
-
- /* rh := rh + b */
- if (!BN_GF2m_add(rh, rh, &group->b)) goto err;
-
- /* lh := Y^2 */
- if (!group->meth->field_sqr(group, lh, &point->Y, ctx)) goto err;
-
- /* lh := lh + x*y */
- if (!group->meth->field_mul(group, tmp1, &point->X, &point->Y, ctx)) goto err;
- if (!BN_GF2m_add(lh, lh, tmp1)) goto err;
-
- ret = (0 == BN_GF2m_cmp(lh, rh));
-
+ if (!BN_GF2m_add(lh, &point->X, &group->a)) goto err;
+ if (!field_mul(group, lh, lh, &point->X, ctx)) goto err;
+ if (!BN_GF2m_add(lh, lh, &point->Y)) goto err;
+ if (!field_mul(group, lh, lh, &point->X, ctx)) goto err;
+ if (!BN_GF2m_add(lh, lh, &group->b)) goto err;
+ if (!field_sqr(group, y2, &point->Y, ctx)) goto err;
+ if (!BN_GF2m_add(lh, lh, y2)) goto err;
+ ret = BN_is_zero(lh);