Abstract out verify logic for fe_sqr

bitcoin-core · May 11, 2023 · 6ab3508 · 6ab3508
1 parent 4c25f6e
commit 6ab3508
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Showing 4 changed files with 20 additions and 22 deletions.
diff --git a/src/field.h b/src/field.h
@@ -91,6 +91,7 @@ static const secp256k1_fe secp256k1_const_beta = SECP256K1_FE_CONST(
 #  define secp256k1_fe_mul_int secp256k1_fe_impl_mul_int
 #  define secp256k1_fe_add secp256k1_fe_impl_add
 #  define secp256k1_fe_mul secp256k1_fe_impl_mul
+#  define secp256k1_fe_sqr secp256k1_fe_impl_sqr
 #endif /* !defined(VERIFY) */
 
 /** Normalize a field element.
@@ -236,8 +237,13 @@ static void secp256k1_fe_add(secp256k1_fe *r, const secp256k1_fe *a);
  */
 static void secp256k1_fe_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b);
 
-/** Sets a field element to be the square of another. Requires the input's magnitude to be at most 8.
- *  The output magnitude is 1 (but not guaranteed to be normalized). */
+/** Square a field element.
+ *
+ * On input, a must be a valid field element; r does not need to be initialized. The magnitude
+ * of a must not exceed 8.
+ * Performs {r = a**2}
+ * On output, r will have magnitude 1, but won't be normalized.
+ */
 static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a);
 
 /** If a has a square root, it is computed in r and 1 is returned. If a does not

diff --git a/src/field_10x26_impl.h b/src/field_10x26_impl.h
@@ -1031,17 +1031,8 @@ SECP256K1_INLINE static void secp256k1_fe_impl_mul(secp256k1_fe *r, const secp25
     secp256k1_fe_mul_inner(r->n, a->n, b->n);
 }
 
-static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->magnitude <= 8);
-    secp256k1_fe_verify(a);
-#endif
+SECP256K1_INLINE static void secp256k1_fe_impl_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
     secp256k1_fe_sqr_inner(r->n, a->n);
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
 static SECP256K1_INLINE void secp256k1_fe_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag) {

diff --git a/src/field_5x52_impl.h b/src/field_5x52_impl.h
@@ -365,17 +365,8 @@ SECP256K1_INLINE static void secp256k1_fe_impl_mul(secp256k1_fe *r, const secp25
     secp256k1_fe_mul_inner(r->n, a->n, b->n);
 }
 
-static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->magnitude <= 8);
-    secp256k1_fe_verify(a);
-#endif
+SECP256K1_INLINE static void secp256k1_fe_impl_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
     secp256k1_fe_sqr_inner(r->n, a->n);
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
 static SECP256K1_INLINE void secp256k1_fe_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag) {

diff --git a/src/field_impl.h b/src/field_impl.h
@@ -300,6 +300,16 @@ SECP256K1_INLINE static void secp256k1_fe_mul(secp256k1_fe *r, const secp256k1_f
     r->normalized = 0;
     secp256k1_fe_verify(r);
 }
+
+static void secp256k1_fe_impl_sqr(secp256k1_fe *r, const secp256k1_fe *a);
+SECP256K1_INLINE static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
+    secp256k1_fe_verify(a);
+    VERIFY_CHECK(a->magnitude <= 8);
+    secp256k1_fe_impl_sqr(r, a);
+    r->magnitude = 1;
+    r->normalized = 0;
+    secp256k1_fe_verify(r);
+}
 #endif /* defined(VERIFY) */
 
 #endif /* SECP256K1_FIELD_IMPL_H */