feedc0de/wolfssl
1
0
Fork 0
forked from wolfSSL/wolfssl
Code Pull Requests Activity

ECDSA sign: cleanup comments and variables

Browse Source 
Remove mod at end as mulmod does this.
Change mp_add to mp_addmod_ct to keep the size of numbers to less than
order for mp_mulmod.
This commit is contained in:
Sean Parkinson
2021-01-27 09:39:11 +10:00
parent 9c34ecc130
commit c739b4d474
1 changed files with 21 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

39
wolfcrypt/src/ecc.c
View File

@ -5544,43 +5544,46 @@ int wc_ecc_sign_hash_ex(const byte* in, word32 inlen, WC_RNG* rng,
if (err != MP_OKAY) break;
if (mp_iszero(r) == MP_NO) {
mp_int* ep = &pubkey->k;
mp_int* kp = &pubkey->k;
mp_int* x = &key->k;
/* find s = (e + xr)/k
= b.(e/k.b + x.r/k.b) */
/* k = k.b */
err = mp_mulmod(&pubkey->k, b, curve->order, &pubkey->k);
/* k' = k.b */
err = mp_mulmod(&pubkey->k, b, curve->order, kp);
if (err != MP_OKAY) break;
/* k = 1/k.b */
err = mp_invmod(&pubkey->k, curve->order, &pubkey->k);
/* k' = 1/k.b
= 1/k' */
err = mp_invmod(kp, curve->order, kp);
if (err != MP_OKAY) break;
/* s = x.r */
err = mp_mulmod(&key->k, r, curve->order, s);
err = mp_mulmod(x, r, curve->order, s);
if (err != MP_OKAY) break;
/* s = x.r/k.b */
err = mp_mulmod(&pubkey->k, s, curve->order, s);
/* s = x.r/k.b
= k'.s */
err = mp_mulmod(kp, s, curve->order, s);
if (err != MP_OKAY) break;
/* e = e/k.b */
err = mp_mulmod(&pubkey->k, e, curve->order, &pubkey->k);
/* e' = e/k.b
= e.k' */
err = mp_mulmod(kp, e, curve->order, ep);
if (err != MP_OKAY) break;
/* s = e/k.b + x.r/k.b
= (e + x.r)/k.b */
err = mp_add(&pubkey->k, s, s);
/* s = e/k.b + x.r/k.b = (e + x.r)/k.b
= e' + s */
err = mp_addmod_ct(ep, s, curve->order, s);
if (err != MP_OKAY) break;
/* s = b.(e + x.r)/k.b
= (e + x.r)/k */
/* s = b.(e + x.r)/k.b = (e + x.r)/k
= b.s */
err = mp_mulmod(s, b, curve->order, s);
if (err != MP_OKAY) break;
/* s = (e + xr)/k */
err = mp_mod(s, curve->order, s);
if (err != MP_OKAY) break;
if (mp_iszero(s) == MP_NO) {
/* sign successful */
break;