mirror of
https://github.com/henrydcase/pqc.git
synced 2024-12-04 21:34:01 +00:00
281 lines
10 KiB
C
281 lines
10 KiB
C
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#include "cbd.h"
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#include "ntt.h"
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#include "params.h"
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#include "poly.h"
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#include "reduce.h"
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#include "symmetric.h"
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#include <stdint.h>
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/*************************************************
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* Name: poly_compress
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*
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* Description: Compression and subsequent serialization of a polynomial
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*
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* Arguments: - uint8_t *r: pointer to output byte array (needs space for KYBER_POLYCOMPRESSEDBYTES bytes)
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* - const poly *a: pointer to input polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_compress(uint8_t *r, poly *a) {
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uint8_t t[8];
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size_t k = 0;
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PQCLEAN_KYBER76890S_CLEAN_poly_csubq(a);
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for (size_t i = 0; i < KYBER_N; i += 8) {
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for (size_t j = 0; j < 8; j++) {
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t[j] = ((((uint32_t)a->coeffs[i + j] << 4) + KYBER_Q / 2) / KYBER_Q) & 15;
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}
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r[k] = (uint8_t)(t[0] | (t[1] << 4));
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r[k + 1] = (uint8_t)(t[2] | (t[3] << 4));
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r[k + 2] = (uint8_t)(t[4] | (t[5] << 4));
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r[k + 3] = (uint8_t)(t[6] | (t[7] << 4));
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k += 4;
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}
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}
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/*************************************************
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* Name: poly_decompress
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*
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* Description: De-serialization and subsequent decompression of a polynomial;
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* approximate inverse of poly_compress
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*
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* Arguments: - poly *r: pointer to output polynomial
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* - const uint8_t *a: pointer to input byte array (of length KYBER_POLYCOMPRESSEDBYTES bytes)
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_decompress(poly *r, const uint8_t *a) {
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for (size_t i = 0; i < KYBER_N; i += 8) {
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r->coeffs[i + 0] = (int16_t)((((a[0] & 15) * KYBER_Q) + 8) >> 4);
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r->coeffs[i + 1] = (int16_t)((((a[0] >> 4) * KYBER_Q) + 8) >> 4);
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r->coeffs[i + 2] = (int16_t)((((a[1] & 15) * KYBER_Q) + 8) >> 4);
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r->coeffs[i + 3] = (int16_t)((((a[1] >> 4) * KYBER_Q) + 8) >> 4);
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r->coeffs[i + 4] = (int16_t)((((a[2] & 15) * KYBER_Q) + 8) >> 4);
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r->coeffs[i + 5] = (int16_t)((((a[2] >> 4) * KYBER_Q) + 8) >> 4);
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r->coeffs[i + 6] = (int16_t)((((a[3] & 15) * KYBER_Q) + 8) >> 4);
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r->coeffs[i + 7] = (int16_t)((((a[3] >> 4) * KYBER_Q) + 8) >> 4);
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a += 4;
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}
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}
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/*************************************************
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* Name: poly_tobytes
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*
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* Description: Serialization of a polynomial
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*
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* Arguments: - uint8_t *r: pointer to output byte array (needs space for KYBER_POLYBYTES bytes)
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* - const poly *a: pointer to input polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_tobytes(uint8_t *r, poly *a) {
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int16_t t0, t1;
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PQCLEAN_KYBER76890S_CLEAN_poly_csubq(a);
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for (size_t i = 0; i < KYBER_N / 2; i++) {
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t0 = a->coeffs[2 * i];
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t1 = a->coeffs[2 * i + 1];
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r[3 * i] = t0 & 0xff;
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r[3 * i + 1] = (uint8_t)((t0 >> 8) | ((t1 & 0xf) << 4));
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r[3 * i + 2] = (uint8_t)(t1 >> 4);
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}
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}
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/*************************************************
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* Name: poly_frombytes
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*
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* Description: De-serialization of a polynomial;
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* inverse of poly_tobytes
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*
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* Arguments: - poly *r: pointer to output polynomial
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* - const uint8_t *a: pointer to input byte array (of KYBER_POLYBYTES bytes)
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_frombytes(poly *r, const uint8_t *a) {
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for (size_t i = 0; i < KYBER_N / 2; i++) {
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r->coeffs[2 * i] = (int16_t)(a[3 * i] | ((uint16_t)a[3 * i + 1] & 0x0f) << 8);
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r->coeffs[2 * i + 1] = (int16_t)(a[3 * i + 1] >> 4 | ((uint16_t)a[3 * i + 2] & 0xff) << 4);
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}
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}
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/*************************************************
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* Name: poly_getnoise
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*
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* Description: Sample a polynomial deterministically from a seed and a nonce,
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* with output polynomial close to centered binomial distribution
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* with parameter KYBER_ETA
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*
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* Arguments: - poly *r: pointer to output polynomial
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* - const uint8_t *seed: pointer to input seed (pointing to array of length KYBER_SYMBYTES bytes)
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* - uint8_t nonce: one-byte input nonce
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_getnoise(poly *r, const uint8_t *seed, uint8_t nonce) {
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uint8_t buf[KYBER_ETA * KYBER_N / 4];
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prf(buf, KYBER_ETA * KYBER_N / 4, seed, nonce);
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PQCLEAN_KYBER76890S_CLEAN_cbd(r, buf);
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}
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/*************************************************
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* Name: poly_ntt
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*
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* Description: Computes negacyclic number-theoretic transform (NTT) of
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* a polynomial in place;
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* inputs assumed to be in normal order, output in bitreversed order
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*
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* Arguments: - uint16_t *r: pointer to in/output polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_ntt(poly *r) {
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PQCLEAN_KYBER76890S_CLEAN_ntt(r->coeffs);
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PQCLEAN_KYBER76890S_CLEAN_poly_reduce(r);
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}
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/*************************************************
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* Name: poly_invntt
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*
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* Description: Computes inverse of negacyclic number-theoretic transform (NTT) of
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* a polynomial in place;
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* inputs assumed to be in bitreversed order, output in normal order
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*
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* Arguments: - uint16_t *a: pointer to in/output polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_invntt(poly *r) {
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PQCLEAN_KYBER76890S_CLEAN_invntt(r->coeffs);
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}
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/*************************************************
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* Name: poly_basemul
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*
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* Description: Multiplication of two polynomials in NTT domain
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*
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* Arguments: - poly *r: pointer to output polynomial
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* - const poly *a: pointer to first input polynomial
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* - const poly *b: pointer to second input polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_basemul(poly *r, const poly *a, const poly *b) {
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for (size_t i = 0; i < KYBER_N / 4; ++i) {
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PQCLEAN_KYBER76890S_CLEAN_basemul(
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r->coeffs + 4 * i,
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a->coeffs + 4 * i,
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b->coeffs + 4 * i,
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PQCLEAN_KYBER76890S_CLEAN_zetas[64 + i]);
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PQCLEAN_KYBER76890S_CLEAN_basemul(
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r->coeffs + 4 * i + 2,
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a->coeffs + 4 * i + 2,
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b->coeffs + 4 * i + 2,
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-PQCLEAN_KYBER76890S_CLEAN_zetas[64 + i]);
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}
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}
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/*************************************************
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* Name: poly_frommont
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*
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* Description: Inplace conversion of all coefficients of a polynomial
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* from Montgomery domain to normal domain
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*
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* Arguments: - poly *r: pointer to input/output polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_frommont(poly *r) {
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const int16_t f = (1ULL << 32) % KYBER_Q;
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for (size_t i = 0; i < KYBER_N; i++) {
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r->coeffs[i] = PQCLEAN_KYBER76890S_CLEAN_montgomery_reduce(
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(int32_t)r->coeffs[i] * f);
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}
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}
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/*************************************************
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* Name: poly_reduce
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*
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* Description: Applies Barrett reduction to all coefficients of a polynomial
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* for details of the Barrett reduction see comments in reduce.c
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*
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* Arguments: - poly *r: pointer to input/output polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_reduce(poly *r) {
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for (size_t i = 0; i < KYBER_N; i++) {
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r->coeffs[i] = PQCLEAN_KYBER76890S_CLEAN_barrett_reduce(r->coeffs[i]);
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}
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}
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/*************************************************
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* Name: poly_csubq
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*
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* Description: Applies conditional subtraction of q to each coefficient of a polynomial
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* for details of conditional subtraction of q see comments in reduce.c
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*
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* Arguments: - poly *r: pointer to input/output polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_csubq(poly *r) {
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for (size_t i = 0; i < KYBER_N; i++) {
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r->coeffs[i] = PQCLEAN_KYBER76890S_CLEAN_csubq(r->coeffs[i]);
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}
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}
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/*************************************************
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* Name: poly_add
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*
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* Description: Add two polynomials
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*
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* Arguments: - poly *r: pointer to output polynomial
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* - const poly *a: pointer to first input polynomial
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* - const poly *b: pointer to second input polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_add(poly *r, const poly *a, const poly *b) {
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for (size_t i = 0; i < KYBER_N; i++) {
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r->coeffs[i] = a->coeffs[i] + b->coeffs[i];
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}
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}
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/*************************************************
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* Name: poly_sub
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*
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* Description: Subtract two polynomials
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*
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* Arguments: - poly *r: pointer to output polynomial
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* - const poly *a: pointer to first input polynomial
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* - const poly *b: pointer to second input polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_sub(poly *r, const poly *a, const poly *b) {
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for (size_t i = 0; i < KYBER_N; i++) {
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r->coeffs[i] = a->coeffs[i] - b->coeffs[i];
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}
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}
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/*************************************************
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* Name: poly_frommsg
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*
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* Description: Convert 32-byte message to polynomial
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*
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* Arguments: - poly *r: pointer to output polynomial
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* - const uint8_t *msg: pointer to input message
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_frommsg(poly *r, const uint8_t msg[KYBER_SYMBYTES]) {
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uint16_t mask;
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for (size_t i = 0; i < KYBER_SYMBYTES; i++) {
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for (size_t j = 0; j < 8; j++) {
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mask = -((msg[i] >> j) & 1);
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r->coeffs[8 * i + j] = mask & ((KYBER_Q + 1) / 2);
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}
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}
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}
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/*************************************************
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* Name: poly_tomsg
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*
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* Description: Convert polynomial to 32-byte message
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*
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* Arguments: - uint8_t *msg: pointer to output message
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* - const poly *a: pointer to input polynomial
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**************************************************/
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void PQCLEAN_KYBER76890S_CLEAN_poly_tomsg(uint8_t msg[KYBER_SYMBYTES], poly *a) {
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uint16_t t;
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PQCLEAN_KYBER76890S_CLEAN_poly_csubq(a);
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for (size_t i = 0; i < KYBER_SYMBYTES; i++) {
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msg[i] = 0;
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for (size_t j = 0; j < 8; j++) {
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t = (((a->coeffs[8 * i + j] << 1) + KYBER_Q / 2) / KYBER_Q) & 1;
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msg[i] |= t << j;
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}
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}
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}
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