cfb615781
Denys Vlasenko
2021-11-28
Subject
tls: P256: simplify sp_256_mont_inv_8 (no need for a temporary)
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Commit Diff GitHub →
networking/tls_sp_c32.c+4 -6
| @@ -938,7 +938,7 @@ static void sp_256_mont_sqr_8(sp_digit* r, const sp_digit* a | |
| /* Invert the number, in Montgomery form, modulo the modulus (prime) of the | |
| * P256 curve. (r = 1 / a mod m) | |
| * | |
| - | * r Inverse result. |
| + | * r Inverse result. Must not coincide with a. |
| * a Number to invert. | |
| */ | |
| #if 0 | |
| @@ -952,17 +952,15 @@ static void sp_256_mont_sqr_8(sp_digit* r, const sp_digit* a | |
| #endif | |
| static void sp_256_mont_inv_8(sp_digit* r, sp_digit* a) | |
| { | |
| - | sp_digit t[8]; |
| int i; | |
| - | memcpy(t, a, sizeof(sp_digit) * 8); |
| + | memcpy(r, a, sizeof(sp_digit) * 8); |
| for (i = 254; i >= 0; i--) { | |
| - | sp_256_mont_sqr_8(t, t /*, p256_mod, p256_mp_mod*/); |
| + | sp_256_mont_sqr_8(r, r /*, p256_mod, p256_mp_mod*/); |
| /*if (p256_mod_2[i / 32] & ((sp_digit)1 << (i % 32)))*/ | |
| if (i >= 224 || i == 192 || (i <= 95 && i != 1)) | |
| - | sp_256_mont_mul_8(t, t, a /*, p256_mod, p256_mp_mod*/); |
| + | sp_256_mont_mul_8(r, r, a /*, p256_mod, p256_mp_mod*/); |
| } | |
| - | memcpy(r, t, sizeof(sp_digit) * 8); |
| } | |
| /* Multiply a number by Montogmery normalizer mod modulus (prime). | |