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#include "cbd.h"
#include "ntt.h"
#include "params.h"
#include "poly.h"
#include "reduce.h"
#include "symmetric.h"
#include <stdint.h>
/*************************************************
* Name: poly_compress
*
* Description: Compression and subsequent serialization of a polynomial
*
* Arguments: - uint8_t *r: pointer to output byte array (needs space for KYBER_POLYCOMPRESSEDBYTES bytes)
* - const poly *a: pointer to input polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_compress(uint8_t *r, poly *a) {
uint8_t t[8];
size_t k = 0;
PQCLEAN_KYBER512_CLEAN_poly_csubq(a);
for (size_t i = 0; i < KYBER_N; i += 8) {
for (size_t j = 0; j < 8; j++) {
t[j] = ((((uint32_t)a->coeffs[i + j] << 3) + KYBER_Q / 2) / KYBER_Q) & 7;
}
r[k] = (uint8_t)( t[0] | (t[1] << 3) | (t[2] << 6));
r[k + 1] = (uint8_t)((t[2] >> 2) | (t[3] << 1) | (t[4] << 4) | (t[5] << 7));
r[k + 2] = (uint8_t)((t[5] >> 1) | (t[6] << 2) | (t[7] << 5));
k += 3;
}
}
/*************************************************
* Name: poly_decompress
*
* Description: De-serialization and subsequent decompression of a polynomial;
* approximate inverse of poly_compress
*
* Arguments: - poly *r: pointer to output polynomial
* - const uint8_t *a: pointer to input byte array (of length KYBER_POLYCOMPRESSEDBYTES bytes)
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_decompress(poly *r, const uint8_t *a) {
for (size_t i = 0; i < KYBER_N; i += 8) {
r->coeffs[i + 0] = (int16_t)( (((a[0] & 7) * KYBER_Q) + 4) >> 3);
r->coeffs[i + 1] = (int16_t)(((((a[0] >> 3) & 7) * KYBER_Q) + 4) >> 3);
r->coeffs[i + 2] = (int16_t)(((((a[0] >> 6) | ((a[1] << 2) & 4)) * KYBER_Q) + 4) >> 3);
r->coeffs[i + 3] = (int16_t)(((((a[1] >> 1) & 7) * KYBER_Q) + 4) >> 3);
r->coeffs[i + 4] = (int16_t)(((((a[1] >> 4) & 7) * KYBER_Q) + 4) >> 3);
r->coeffs[i + 5] = (int16_t)(((((a[1] >> 7) | ((a[2] << 1) & 6)) * KYBER_Q) + 4) >> 3);
r->coeffs[i + 6] = (int16_t)(((((a[2] >> 2) & 7) * KYBER_Q) + 4) >> 3);
r->coeffs[i + 7] = (int16_t)(((((a[2] >> 5)) * KYBER_Q) + 4) >> 3);
a += 3;
}
}
/*************************************************
* Name: poly_tobytes
*
* Description: Serialization of a polynomial
*
* Arguments: - uint8_t *r: pointer to output byte array (needs space for KYBER_POLYBYTES bytes)
* - const poly *a: pointer to input polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_tobytes(uint8_t *r, poly *a) {
PQCLEAN_KYBER512_CLEAN_poly_csubq(a);
for (size_t i = 0; i < KYBER_N / 2; i++) {
int16_t t0 = a->coeffs[2 * i];
int16_t t1 = a->coeffs[2 * i + 1];
r[3 * i] = t0 & 0xff;
r[3 * i + 1] = (uint8_t)((t0 >> 8) | ((t1 & 0xf) << 4));
r[3 * i + 2] = (uint8_t)(t1 >> 4);
}
}
/*************************************************
* Name: poly_frombytes
*
* Description: De-serialization of a polynomial;
* inverse of poly_tobytes
*
* Arguments: - poly *r: pointer to output polynomial
* - const uint8_t *a: pointer to input byte array (of KYBER_POLYBYTES bytes)
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_frombytes(poly *r, const uint8_t *a) {
for (size_t i = 0; i < KYBER_N / 2; i++) {
r->coeffs[2 * i] = (int16_t)(a[3 * i] | ((uint16_t)a[3 * i + 1] & 0x0f) << 8);
r->coeffs[2 * i + 1] = (int16_t)(a[3 * i + 1] >> 4 | ((uint16_t)a[3 * i + 2] & 0xff) << 4);
}
}
/*************************************************
* Name: poly_getnoise
*
* Description: Sample a polynomial deterministically from a seed and a nonce,
* with output polynomial close to centered binomial distribution
* with parameter KYBER_ETA
*
* Arguments: - poly *r: pointer to output polynomial
* - const uint8_t *seed: pointer to input seed (pointing to array of length KYBER_SYMBYTES bytes)
* - uint8_t nonce: one-byte input nonce
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_getnoise(poly *r, const uint8_t *seed, uint8_t nonce) {
uint8_t buf[KYBER_ETA * KYBER_N / 4];
prf(buf, KYBER_ETA * KYBER_N / 4, seed, nonce);
PQCLEAN_KYBER512_CLEAN_cbd(r, buf);
}
/*************************************************
* Name: poly_ntt
*
* Description: Computes negacyclic number-theoretic transform (NTT) of
* a polynomial in place;
* inputs assumed to be in normal order, output in bitreversed order
*
* Arguments: - uint16_t *r: pointer to in/output polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_ntt(poly *r) {
PQCLEAN_KYBER512_CLEAN_ntt(r->coeffs);
PQCLEAN_KYBER512_CLEAN_poly_reduce(r);
}
/*************************************************
* Name: poly_invntt
*
* Description: Computes inverse of negacyclic number-theoretic transform (NTT) of
* a polynomial in place;
* inputs assumed to be in bitreversed order, output in normal order
*
* Arguments: - uint16_t *a: pointer to in/output polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_invntt(poly *r) {
PQCLEAN_KYBER512_CLEAN_invntt(r->coeffs);
}
/*************************************************
* Name: poly_basemul
*
* Description: Multiplication of two polynomials in NTT domain
*
* Arguments: - poly *r: pointer to output polynomial
* - const poly *a: pointer to first input polynomial
* - const poly *b: pointer to second input polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_basemul(poly *r, const poly *a, const poly *b) {
for (size_t i = 0; i < KYBER_N / 4; ++i) {
PQCLEAN_KYBER512_CLEAN_basemul(
r->coeffs + 4 * i,
a->coeffs + 4 * i,
b->coeffs + 4 * i,
PQCLEAN_KYBER512_CLEAN_zetas[64 + i]);
PQCLEAN_KYBER512_CLEAN_basemul(
r->coeffs + 4 * i + 2,
a->coeffs + 4 * i + 2,
b->coeffs + 4 * i + 2,
-PQCLEAN_KYBER512_CLEAN_zetas[64 + i]);
}
}
/*************************************************
* Name: poly_frommont
*
* Description: Inplace conversion of all coefficients of a polynomial
* from Montgomery domain to normal domain
*
* Arguments: - poly *r: pointer to input/output polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_frommont(poly *r) {
const int16_t f = (1ULL << 32) % KYBER_Q;
for (size_t i = 0; i < KYBER_N; i++) {
r->coeffs[i] = PQCLEAN_KYBER512_CLEAN_montgomery_reduce(
(int32_t)r->coeffs[i] * f);
}
}
/*************************************************
* Name: poly_reduce
*
* Description: Applies Barrett reduction to all coefficients of a polynomial
* for details of the Barrett reduction see comments in reduce.c
*
* Arguments: - poly *r: pointer to input/output polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_reduce(poly *r) {
for (size_t i = 0; i < KYBER_N; i++) {
r->coeffs[i] = PQCLEAN_KYBER512_CLEAN_barrett_reduce(r->coeffs[i]);
}
}
/*************************************************
* Name: poly_csubq
*
* Description: Applies conditional subtraction of q to each coefficient of a polynomial
* for details of conditional subtraction of q see comments in reduce.c
*
* Arguments: - poly *r: pointer to input/output polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_csubq(poly *r) {
for (size_t i = 0; i < KYBER_N; i++) {
r->coeffs[i] = PQCLEAN_KYBER512_CLEAN_csubq(r->coeffs[i]);
}
}
/*************************************************
* Name: poly_add
*
* Description: Add two polynomials
*
* Arguments: - poly *r: pointer to output polynomial
* - const poly *a: pointer to first input polynomial
* - const poly *b: pointer to second input polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_add(poly *r, const poly *a, const poly *b) {
for (size_t i = 0; i < KYBER_N; i++) {
r->coeffs[i] = a->coeffs[i] + b->coeffs[i];
}
}
/*************************************************
* Name: poly_sub
*
* Description: Subtract two polynomials
*
* Arguments: - poly *r: pointer to output polynomial
* - const poly *a: pointer to first input polynomial
* - const poly *b: pointer to second input polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_sub(poly *r, const poly *a, const poly *b) {
for (size_t i = 0; i < KYBER_N; i++) {
r->coeffs[i] = a->coeffs[i] - b->coeffs[i];
}
}
/*************************************************
* Name: poly_frommsg
*
* Description: Convert 32-byte message to polynomial
*
* Arguments: - poly *r: pointer to output polynomial
* - const uint8_t *msg: pointer to input message
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_frommsg(poly *r, const uint8_t msg[KYBER_SYMBYTES]) {
uint16_t mask;
for (size_t i = 0; i < KYBER_SYMBYTES; i++) {
for (size_t j = 0; j < 8; j++) {
mask = -((msg[i] >> j) & 1);
r->coeffs[8 * i + j] = mask & ((KYBER_Q + 1) / 2);
}
}
}
/*************************************************
* Name: poly_tomsg
*
* Description: Convert polynomial to 32-byte message
*
* Arguments: - uint8_t *msg: pointer to output message
* - const poly *a: pointer to input polynomial
**************************************************/
void PQCLEAN_KYBER512_CLEAN_poly_tomsg(uint8_t msg[KYBER_SYMBYTES], poly *a) {
uint16_t t;
PQCLEAN_KYBER512_CLEAN_poly_csubq(a);
for (size_t i = 0; i < KYBER_SYMBYTES; i++) {
msg[i] = 0;
for (size_t j = 0; j < 8; j++) {
t = (((a->coeffs[8 * i + j] << 1) + KYBER_Q / 2) / KYBER_Q) & 1;
msg[i] |= t << j;
}
}
}
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