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Fix for constant time (step 1)

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NIIBE Yutaka
2014-01-21 13:25:30 +09:00
parent 3bb3c6e9d8
commit 007eada502
1 changed files with 6 additions and 4 deletions
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10
src/mod.c
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@@ -105,8 +105,7 @@ mod_reduce (bn256 *X, const bn512 *A, const bn256 *B, const bn256 *MU_lower)
q_big->word[0] = A->word[0];
bn256_mul (tmp, q, B);
if (carry)
tmp->word[8] += B->word[0];
tmp->word[8] += carry * B->word[0];
tmp->word[15] = tmp->word[14] = tmp->word[13] = tmp->word[12]
= tmp->word[11] = tmp->word[10] = tmp->word[9] = 0;
@@ -123,8 +122,11 @@ mod_reduce (bn256 *X, const bn512 *A, const bn256 *B, const bn256 *MU_lower)
carry -= borrow_next;
}
if (bn256_is_ge (X, B))
bn256_sub (X, X, B);
borrow = bn256_sub (q, X, B);
if (borrow)
memcpy (q, X, sizeof (bn256));
else
memcpy (X, q, sizeof (bn256));
}
/**