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| author | Niels Möller <nisse@lysator.liu.se> | 2021-10-26 18:00:07 +0200 |
|---|---|---|
| committer | Niels Möller <nisse@lysator.liu.se> | 2021-10-26 18:00:07 +0200 |
| commit | 652bdc79d991d4755141624fc37f7270e38fdaf1 (patch) | |
| tree | 76392cdcb78eda46f56ae6462770c1f41c33bfc8 /ecc-curve25519.c | |
| parent | 26b0f47b458767ec5a3a4d7980498b03a4e8ded7 (diff) | |
| download | nettle-652bdc79d991d4755141624fc37f7270e38fdaf1.tar.gz | |
New function ecc_mod_zero_p.
* ecc-mod-arith.c (ecc_mod_zero_p): New function.
* ecc-curve25519.c (ecc_curve25519_zero_p): Use it.
* ecc-curve448.c (ecc_curve448_zero_p): Deleted, usage replaced
with ecc_mod_zero_p.
* testsuite/ecc-modinv-test.c (mod_eq_p): Rewritten to use
ecc_mod_zero_p, and require that one input is canonically reduced.
(zero_p): Deleted, usage replaced with ecc_mod_zero_p.
Diffstat (limited to 'ecc-curve25519.c')
| -rw-r--r-- | ecc-curve25519.c | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/ecc-curve25519.c b/ecc-curve25519.c index 3a85f07e..a1d68afd 100644 --- a/ecc-curve25519.c +++ b/ecc-curve25519.c @@ -170,20 +170,17 @@ ecc_curve25519_inv (const struct ecc_modulo *p, ecc_mod_mul (p, rp, ap, rp, scratch); } -/* First, do a canonical reduction, then check if zero */ static int ecc_curve25519_zero_p (const struct ecc_modulo *p, mp_limb_t *xp) { - mp_limb_t cy; +/* First, reduce to < 2p. */ #if PHIGH_BITS > 0 mp_limb_t hi = xp[ECC_LIMB_SIZE-1]; xp[ECC_LIMB_SIZE-1] = (hi & (GMP_NUMB_MASK >> PHIGH_BITS)) + sec_add_1 (xp, xp, ECC_LIMB_SIZE - 1, 19 * (hi >> (GMP_NUMB_BITS - PHIGH_BITS))); #endif - cy = mpn_sub_n (xp, xp, p->m, ECC_LIMB_SIZE); - mpn_cnd_add_n (cy, xp, xp, p->m, ECC_LIMB_SIZE); - return sec_zero_p (xp, ECC_LIMB_SIZE); + return ecc_mod_zero_p (p, xp); } /* Compute x such that x^2 = u/v (mod p). Returns one on success, zero |