pqc/crypto_kem/hqc-rmrs-128/avx2/vector.c
2021-03-24 21:02:49 +00:00

179 lines
5.5 KiB
C

#include "nistseedexpander.h"
#include "parameters.h"
#include "parsing.h"
#include "randombytes.h"
#include "vector.h"
#include <immintrin.h>
#include <stdint.h>
#include <string.h>
/**
* @file vector.c
* @brief Implementation of vectors sampling and some utilities for the HQC scheme
*/
/**
* @brief Generates a vector of a given Hamming weight
*
* This function generates uniformly at random a binary vector of a Hamming weight equal to the parameter <b>weight</b>.
* To generate the vector we have to sample uniformly at random values in the interval [0, PARAM_N -1]. Suppose the PARAM_N is equal to \f$ 70853 \f$, to select a position \f$ r\f$ the function works as follow:
* 1. It makes a call to the seedexpander function to obtain a random number \f$ x\f$ in \f$ [0, 2^{24}[ \f$.
* 2. Let \f$ t = \lfloor {2^{24} \over 70853} \rfloor \times 70853\f$
* 3. If \f$ x \geq t\f$, go to 1
* 4. It return \f$ r = x \mod 70853\f$
*
* The parameter \f$ t \f$ is precomputed and it's denoted by UTILS_REJECTION_THRESHOLD (see the file parameters.h).
*
* @param[in] v Pointer to an array
* @param[in] weight Integer that is the Hamming weight
* @param[in] ctx Pointer to the context of the seed expander
*/
void PQCLEAN_HQCRMRS128_AVX2_vect_set_random_fixed_weight(AES_XOF_struct *ctx, uint64_t *v, uint16_t weight) {
size_t random_bytes_size = 3 * weight;
uint8_t rand_bytes[3 * PARAM_OMEGA_R] = {0};
uint32_t tmp[PARAM_OMEGA_R] = {0};
__m256i bit256[PARAM_OMEGA_R];
__m256i bloc256[PARAM_OMEGA_R];
__m256i posCmp256 = _mm256_set_epi64x(3, 2, 1, 0);
__m256i pos256;
__m256i mask256;
__m256i aux;
__m256i i256;
uint64_t bloc, pos, bit64;
uint8_t inc;
size_t i, j, k;
i = 0;
j = random_bytes_size;
while (i < weight) {
do {
if (j == random_bytes_size) {
seedexpander(ctx, rand_bytes, random_bytes_size);
j = 0;
}
tmp[i] = ((uint32_t) rand_bytes[j++]) << 16;
tmp[i] |= ((uint32_t) rand_bytes[j++]) << 8;
tmp[i] |= rand_bytes[j++];
} while (tmp[i] >= UTILS_REJECTION_THRESHOLD);
tmp[i] = tmp[i] % PARAM_N;
inc = 1;
for (k = 0; k < i; k++) {
if (tmp[k] == tmp[i]) {
inc = 0;
}
}
i += inc;
}
for (i = 0; i < weight; i++) {
// we store the bloc number and bit position of each vb[i]
bloc = tmp[i] >> 6;
bloc256[i] = _mm256_set1_epi64x(bloc >> 2);
pos = (bloc & 0x3UL);
pos256 = _mm256_set1_epi64x(pos);
mask256 = _mm256_cmpeq_epi64(pos256, posCmp256);
bit64 = 1ULL << (tmp[i] & 0x3f);
bit256[i] = _mm256_set1_epi64x(bit64)&mask256;
}
for (i = 0; i < CEIL_DIVIDE(PARAM_N, 256); i++) {
aux = _mm256_loadu_si256(((__m256i *)v) + i);
i256 = _mm256_set1_epi64x(i);
for (j = 0; j < weight; j++) {
mask256 = _mm256_cmpeq_epi64(bloc256[j], i256);
aux ^= bit256[j] & mask256;
}
_mm256_storeu_si256(((__m256i *)v) + i, aux);
}
}
/**
* @brief Generates a random vector of dimension <b>PARAM_N</b>
*
* This function generates a random binary vector of dimension <b>PARAM_N</b>. It generates a random
* array of bytes using the seedexpander function, and drop the extra bits using a mask.
*
* @param[in] v Pointer to an array
* @param[in] ctx Pointer to the context of the seed expander
*/
void PQCLEAN_HQCRMRS128_AVX2_vect_set_random(AES_XOF_struct *ctx, uint64_t *v) {
uint8_t rand_bytes[VEC_N_SIZE_BYTES] = {0};
seedexpander(ctx, rand_bytes, VEC_N_SIZE_BYTES);
PQCLEAN_HQCRMRS128_AVX2_load8_arr(v, VEC_N_SIZE_64, rand_bytes, VEC_N_SIZE_BYTES);
v[VEC_N_SIZE_64 - 1] &= RED_MASK;
}
/**
* @brief Adds two vectors
*
* @param[out] o Pointer to an array that is the result
* @param[in] v1 Pointer to an array that is the first vector
* @param[in] v2 Pointer to an array that is the second vector
* @param[in] size Integer that is the size of the vectors
*/
void PQCLEAN_HQCRMRS128_AVX2_vect_add(uint64_t *o, const uint64_t *v1, const uint64_t *v2, uint32_t size) {
for (uint32_t i = 0; i < size; ++i) {
o[i] = v1[i] ^ v2[i];
}
}
/**
* @brief Compares two vectors
*
* @param[in] v1 Pointer to an array that is first vector
* @param[in] v2 Pointer to an array that is second vector
* @param[in] size Integer that is the size of the vectors
* @returns 0 if the vectors are equals and a negative/psotive value otherwise
*/
uint8_t PQCLEAN_HQCRMRS128_AVX2_vect_compare(const uint8_t *v1, const uint8_t *v2, uint32_t size) {
uint64_t r = 0;
for (size_t i = 0; i < size; i++) {
r |= v1[i] ^ v2[i];
}
r = (~r + 1) >> 63;
return (uint8_t) r;
}
/**
* @brief Resize a vector so that it contains <b>size_o</b> bits
*
* @param[out] o Pointer to the output vector
* @param[in] size_o Integer that is the size of the output vector in bits
* @param[in] v Pointer to the input vector
* @param[in] size_v Integer that is the size of the input vector in bits
*/
void PQCLEAN_HQCRMRS128_AVX2_vect_resize(uint64_t *o, uint32_t size_o, const uint64_t *v, uint32_t size_v) {
uint64_t mask = 0x7FFFFFFFFFFFFFFF;
int8_t val = 0;
if (size_o < size_v) {
if (size_o % 64) {
val = 64 - (size_o % 64);
}
memcpy(o, v, VEC_N1N2_SIZE_BYTES);
for (int8_t i = 0; i < val; ++i) {
o[VEC_N1N2_SIZE_64 - 1] &= (mask >> i);
}
} else {
memcpy(o, v, CEIL_DIVIDE(size_v, 8));
}
}