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Henry Case 2021-03-12 12:03:27 +00:00
parent 070a06bf62
commit 8f2a3f5f87
1 changed files with 24 additions and 5 deletions
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src/sign/dilithium/dilithium2/clean/rounding.c
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@ -66,20 +66,39 @@ int32_t PQCLEAN_DILITHIUM2_CLEAN_decompose(int32_t *a0, int32_t a) {
*a0 = r; *a0 = r;
} }
// CASE: r-r0 = q-1 => r1=0, r0 = r0-1
// OLD // OLD
a1 = (a + 127) >> 7; a1 = (a + 127) >> 7;
a1 = (a1 * 11275 + (1 << 23)) >> 24; a1 = (a1 * 11275 + (1 << 23)) >> 24;
a1 ^= ((43 - a1) >> 31) & a1; a1 ^= ((43 - a1) >> 31) & a1;
// TODO: ten sam trick co w barrett // CASE: r-r0 = q-1 => r1=0, r0 = r0-1
int32_t a2 = ((uint64_t)a-*a0)/(2*GAMMA2); uint64_t a2 = (uint64_t)a - *a0;
if (a2 == (Q-1)) {
a2 = 0;
*a0--;
}
// divide (r-r0)/alpha
// int32_t a2 = ((uint64_t)a-*a0)/(2*GAMMA2);
if ( (a2 >= (2*GAMMA2))) {
a2 = (a2*u) >> 36;
// a2 is divisible by ALPHA=(2*GAMMA2) and hence
// it will always be off by one.
a2++;
}
//if (!a1) a2 = a1;
//*a0 = a - a1 * 2 * GAMMA2; //*a0 = a - a1 * 2 * GAMMA2;
//*a0 -= (((Q - 1) / 2 - *a0) >> 31) & Q; //*a0 -= (((Q - 1) / 2 - *a0) >> 31) & Q;
printf("(%d, %d,\n)", a1, a2); if (a1 != (int32_t)a2)
return a1; printf("OZAPTF: (A1=%d, A2=%d, A=%d R=%d)\n",
a1, (int32_t)a2, a, (a-(*a0)));
// printf("OZAPTF: %d %d %d\n", a, *a0, (a-*a0));
return a2;
} }
/************************************************* /*************************************************