4f86c39515
* Update Dilithium * Alternative montgomery reduce to avoid i386 functest errors * Explicit casts for msvc * More casts; bump upstream version; fix metadata * another cast
93 lines
2.7 KiB
C
93 lines
2.7 KiB
C
#include "params.h"
|
|
#include "rounding.h"
|
|
#include <stdint.h>
|
|
|
|
/*************************************************
|
|
* Name: PQCLEAN_DILITHIUM3_CLEAN_power2round
|
|
*
|
|
* Description: For finite field element a, compute a0, a1 such that
|
|
* a mod^+ Q = a1*2^D + a0 with -2^{D-1} < a0 <= 2^{D-1}.
|
|
* Assumes a to be standard representative.
|
|
*
|
|
* Arguments: - int32_t a: input element
|
|
* - int32_t *a0: pointer to output element a0
|
|
*
|
|
* Returns a1.
|
|
**************************************************/
|
|
int32_t PQCLEAN_DILITHIUM3_CLEAN_power2round(int32_t *a0, int32_t a) {
|
|
int32_t a1;
|
|
|
|
a1 = (a + (1 << (D - 1)) - 1) >> D;
|
|
*a0 = a - (a1 << D);
|
|
return a1;
|
|
}
|
|
|
|
/*************************************************
|
|
* Name: PQCLEAN_DILITHIUM3_CLEAN_decompose
|
|
*
|
|
* Description: For finite field element a, compute high and low bits a0, a1 such
|
|
* that a mod^+ Q = a1*ALPHA + a0 with -ALPHA/2 < a0 <= ALPHA/2 except
|
|
* if a1 = (Q-1)/ALPHA where we set a1 = 0 and
|
|
* -ALPHA/2 <= a0 = a mod^+ Q - Q < 0. Assumes a to be standard
|
|
* representative.
|
|
*
|
|
* Arguments: - int32_t a: input element
|
|
* - int32_t *a0: pointer to output element a0
|
|
*
|
|
* Returns a1.
|
|
**************************************************/
|
|
int32_t PQCLEAN_DILITHIUM3_CLEAN_decompose(int32_t *a0, int32_t a) {
|
|
int32_t a1;
|
|
|
|
a1 = (a + 127) >> 7;
|
|
a1 = (a1 * 1025 + (1 << 21)) >> 22;
|
|
a1 &= 15;
|
|
|
|
*a0 = a - a1 * 2 * GAMMA2;
|
|
*a0 -= (((Q - 1) / 2 - *a0) >> 31) & Q;
|
|
return a1;
|
|
}
|
|
|
|
/*************************************************
|
|
* Name: PQCLEAN_DILITHIUM3_CLEAN_make_hint
|
|
*
|
|
* Description: Compute hint bit indicating whether the low bits of the
|
|
* input element overflow into the high bits.
|
|
*
|
|
* Arguments: - int32_t a0: low bits of input element
|
|
* - int32_t a1: high bits of input element
|
|
*
|
|
* Returns 1 if overflow.
|
|
**************************************************/
|
|
unsigned int PQCLEAN_DILITHIUM3_CLEAN_make_hint(int32_t a0, int32_t a1) {
|
|
if (a0 > GAMMA2 || a0 < -GAMMA2 || (a0 == -GAMMA2 && a1 != 0)) {
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*************************************************
|
|
* Name: PQCLEAN_DILITHIUM3_CLEAN_use_hint
|
|
*
|
|
* Description: Correct high bits according to hint.
|
|
*
|
|
* Arguments: - int32_t a: input element
|
|
* - unsigned int hint: hint bit
|
|
*
|
|
* Returns corrected high bits.
|
|
**************************************************/
|
|
int32_t PQCLEAN_DILITHIUM3_CLEAN_use_hint(int32_t a, unsigned int hint) {
|
|
int32_t a0, a1;
|
|
|
|
a1 = PQCLEAN_DILITHIUM3_CLEAN_decompose(&a0, a);
|
|
if (hint == 0) {
|
|
return a1;
|
|
}
|
|
|
|
if (a0 > 0) {
|
|
return (a1 + 1) & 15;
|
|
}
|
|
return (a1 - 1) & 15;
|
|
}
|