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field: remove secp256k1_fe_equal_var

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`fe_equal_var` hits a fast path only when the inputs are unequal, which is
uncommon among its callers (public key parsing, ECDSA verify).
This commit is contained in:
siv2r
2022-01-31 04:43:57 +05:30
parent bb4efd6404
commit 54058d16fe
7 changed files with 31 additions and 50 deletions
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15
src/field_impl.h
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@@ -31,19 +31,6 @@ SECP256K1_INLINE static int secp256k1_fe_equal(const secp256k1_fe *a, const secp
return secp256k1_fe_normalizes_to_zero(&na);
}
SECP256K1_INLINE static int secp256k1_fe_equal_var(const secp256k1_fe *a, const secp256k1_fe *b) {
secp256k1_fe na;
#ifdef VERIFY
secp256k1_fe_verify(a);
secp256k1_fe_verify(b);
secp256k1_fe_verify_magnitude(a, 1);
secp256k1_fe_verify_magnitude(b, 31);
#endif
secp256k1_fe_negate(&na, a, 1);
secp256k1_fe_add(&na, b);
return secp256k1_fe_normalizes_to_zero_var(&na);
}
static int secp256k1_fe_sqrt(secp256k1_fe * SECP256K1_RESTRICT r, const secp256k1_fe * SECP256K1_RESTRICT a) {
/** Given that p is congruent to 3 mod 4, we can compute the square root of
* a mod p as the (p+1)/4'th power of a.
@@ -151,7 +138,7 @@ static int secp256k1_fe_sqrt(secp256k1_fe * SECP256K1_RESTRICT r, const secp256k
if (!ret) {
secp256k1_fe_negate(&t1, &t1, 1);
secp256k1_fe_normalize_var(&t1);
VERIFY_CHECK(secp256k1_fe_equal_var(&t1, a));
VERIFY_CHECK(secp256k1_fe_equal(&t1, a));
}
#endif
return ret;