Abstract out verify logic for fe_inv{,_var}

This commit is contained in:
Pieter Wuille
2022-01-28 19:20:51 -05:00
parent 3167646072
commit d5aa2f0358
4 changed files with 43 additions and 51 deletions

View File

@@ -492,22 +492,12 @@ static void secp256k1_fe_from_signed62(secp256k1_fe *r, const secp256k1_modinv64
r->n[2] = (a1 >> 42 | a2 << 20) & M52;
r->n[3] = (a2 >> 32 | a3 << 30) & M52;
r->n[4] = (a3 >> 22 | a4 << 40);
#ifdef VERIFY
r->magnitude = 1;
r->normalized = 1;
secp256k1_fe_verify(r);
#endif
}
static void secp256k1_fe_to_signed62(secp256k1_modinv64_signed62 *r, const secp256k1_fe *a) {
const uint64_t M62 = UINT64_MAX >> 2;
const uint64_t a0 = a->n[0], a1 = a->n[1], a2 = a->n[2], a3 = a->n[3], a4 = a->n[4];
#ifdef VERIFY
VERIFY_CHECK(a->normalized);
#endif
r->v[0] = (a0 | a1 << 52) & M62;
r->v[1] = (a1 >> 10 | a2 << 42) & M62;
r->v[2] = (a2 >> 20 | a3 << 32) & M62;
@@ -520,34 +510,24 @@ static const secp256k1_modinv64_modinfo secp256k1_const_modinfo_fe = {
0x27C7F6E22DDACACFLL
};
static void secp256k1_fe_inv(secp256k1_fe *r, const secp256k1_fe *x) {
secp256k1_fe tmp;
static void secp256k1_fe_impl_inv(secp256k1_fe *r, const secp256k1_fe *x) {
secp256k1_fe tmp = *x;
secp256k1_modinv64_signed62 s;
tmp = *x;
secp256k1_fe_normalize(&tmp);
secp256k1_fe_to_signed62(&s, &tmp);
secp256k1_modinv64(&s, &secp256k1_const_modinfo_fe);
secp256k1_fe_from_signed62(r, &s);
#ifdef VERIFY
VERIFY_CHECK(secp256k1_fe_normalizes_to_zero(r) == secp256k1_fe_normalizes_to_zero(&tmp));
#endif
}
static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *x) {
secp256k1_fe tmp;
static void secp256k1_fe_impl_inv_var(secp256k1_fe *r, const secp256k1_fe *x) {
secp256k1_fe tmp = *x;
secp256k1_modinv64_signed62 s;
tmp = *x;
secp256k1_fe_normalize_var(&tmp);
secp256k1_fe_to_signed62(&s, &tmp);
secp256k1_modinv64_var(&s, &secp256k1_const_modinfo_fe);
secp256k1_fe_from_signed62(r, &s);
#ifdef VERIFY
VERIFY_CHECK(secp256k1_fe_normalizes_to_zero(r) == secp256k1_fe_normalizes_to_zero(&tmp));
#endif
}
static int secp256k1_fe_is_square_var(const secp256k1_fe *x) {