336 lines
9.1 KiB
C
336 lines
9.1 KiB
C
#include "SABER_indcpa.h"
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#include "SABER_params.h"
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#include "fips202.h"
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#include "pack_unpack.h"
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#include "poly.h"
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#include "poly_mul.h"
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#include "randombytes.h"
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#include <stdint.h>
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#include <string.h>
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/*-----------------------------------------------------------------------------------
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This routine generates a=[Matrix K x K] of 256-coefficient polynomials
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-------------------------------------------------------------------------------------*/
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#define h1 4 //2^(EQ-EP-1)
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#define h2 ( (1<<(SABER_EP-2)) - (1<<(SABER_EP-SABER_ET-1)) + (1<<(SABER_EQ-SABER_EP-1)) )
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static void InnerProd(uint16_t pkcl[SABER_K][SABER_N], uint16_t skpv[SABER_K][SABER_N], uint16_t mod, uint16_t res[SABER_N]);
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static void MatrixVectorMul(polyvec *a, uint16_t skpv[SABER_K][SABER_N], uint16_t res[SABER_K][SABER_N], uint16_t mod, int16_t transpose);
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static void POL2MSG(const uint16_t *message_dec_unpacked, unsigned char *message_dec);
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static void GenMatrix(polyvec *a, const unsigned char *seed) {
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unsigned char buf[SABER_K * SABER_K * (13 * SABER_N / 8)];
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uint16_t temp_ar[SABER_N];
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int i, j, k;
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uint16_t mod = (SABER_Q - 1);
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shake128(buf, sizeof(buf), seed, SABER_SEEDBYTES);
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for (i = 0; i < SABER_K; i++) {
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for (j = 0; j < SABER_K; j++) {
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PQCLEAN_LIGHTSABER_CLEAN_BS2POL(buf + (i * SABER_K + j) * (13 * SABER_N / 8), temp_ar);
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for (k = 0; k < SABER_N; k++) {
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a[i].vec[j].coeffs[k] = (temp_ar[k])& mod ;
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}
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}
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}
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}
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void PQCLEAN_LIGHTSABER_CLEAN_indcpa_kem_keypair(unsigned char *pk, unsigned char *sk) {
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polyvec a[SABER_K];// skpv;
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uint16_t skpv[SABER_K][SABER_N];
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unsigned char seed[SABER_SEEDBYTES];
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unsigned char noiseseed[SABER_COINBYTES];
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int32_t i, j;
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uint16_t mod_q = SABER_Q - 1;
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uint16_t res[SABER_K][SABER_N];
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randombytes(seed, SABER_SEEDBYTES);
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shake128(seed, SABER_SEEDBYTES, seed, SABER_SEEDBYTES); // for not revealing system RNG state
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randombytes(noiseseed, SABER_COINBYTES);
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GenMatrix(a, seed); //sample matrix A
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PQCLEAN_LIGHTSABER_CLEAN_GenSecret(skpv, noiseseed); //generate secret from constant-time binomial distribution
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//------------------------do the matrix vector multiplication and rounding------------
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for (i = 0; i < SABER_K; i++) {
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for (j = 0; j < SABER_N; j++) {
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res[i][j] = 0;
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}
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}
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MatrixVectorMul(a, skpv, res, SABER_Q - 1, 1);
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//-----now rounding
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for (i = 0; i < SABER_K; i++) { //shift right 3 bits
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for (j = 0; j < SABER_N; j++) {
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res[i][j] = (res[i][j] + h1) & (mod_q);
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res[i][j] = (res[i][j] >> (SABER_EQ - SABER_EP));
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}
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}
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//------------------unload and pack sk=3 x (256 coefficients of 14 bits)-------
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PQCLEAN_LIGHTSABER_CLEAN_POLVEC2BS(sk, skpv, SABER_Q);
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//------------------unload and pack pk=256 bits seed and 3 x (256 coefficients of 11 bits)-------
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PQCLEAN_LIGHTSABER_CLEAN_POLVEC2BS(pk, res, SABER_P); // load the public-key coefficients
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for (i = 0; i < SABER_SEEDBYTES; i++) { // now load the seedbytes in PK. Easy since seed bytes are kept in byte format.
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pk[SABER_POLYVECCOMPRESSEDBYTES + i] = seed[i];
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}
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}
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void PQCLEAN_LIGHTSABER_CLEAN_indcpa_kem_enc(const unsigned char *message_received, unsigned char *noiseseed, const unsigned char *pk, unsigned char *ciphertext) {
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uint32_t i, j, k;
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polyvec a[SABER_K]; // skpv;
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unsigned char seed[SABER_SEEDBYTES];
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uint16_t pkcl[SABER_K][SABER_N]; //public key of received by the client
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uint16_t skpv1[SABER_K][SABER_N];
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uint16_t message[SABER_KEYBYTES * 8];
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uint16_t res[SABER_K][SABER_N];
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uint16_t mod_p = SABER_P - 1;
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uint16_t mod_q = SABER_Q - 1;
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uint16_t vprime[SABER_N];
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unsigned char msk_c[SABER_SCALEBYTES_KEM];
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for (i = 0; i < SABER_SEEDBYTES; i++) { // extract the seedbytes from Public Key.
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seed[i] = pk[ SABER_POLYVECCOMPRESSEDBYTES + i];
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}
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GenMatrix(a, seed);
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PQCLEAN_LIGHTSABER_CLEAN_GenSecret(skpv1, noiseseed); //generate secret from constant-time binomial distribution
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//-----------------matrix-vector multiplication and rounding
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for (i = 0; i < SABER_K; i++) {
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for (j = 0; j < SABER_N; j++) {
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res[i][j] = 0;
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}
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}
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MatrixVectorMul(a, skpv1, res, SABER_Q - 1, 0);
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//-----now rounding
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for (i = 0; i < SABER_K; i++) { //shift right 3 bits
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for (j = 0; j < SABER_N; j++) {
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res[i][j] = ( res[i][j] + h1 ) & mod_q;
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res[i][j] = (res[i][j] >> (SABER_EQ - SABER_EP) );
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}
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}
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PQCLEAN_LIGHTSABER_CLEAN_POLVEC2BS(ciphertext, res, SABER_P);
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//*******************client matrix-vector multiplication ends************************************
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//------now calculate the v'
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//-------unpack the public_key
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//pkcl is the b in the protocol
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PQCLEAN_LIGHTSABER_CLEAN_BS2POLVEC(pk, pkcl, SABER_P);
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for (i = 0; i < SABER_N; i++) {
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vprime[i] = 0;
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}
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for (i = 0; i < SABER_K; i++) {
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for (j = 0; j < SABER_N; j++) {
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skpv1[i][j] = skpv1[i][j] & (mod_p);
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}
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}
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// vector-vector scalar multiplication with mod p
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InnerProd(pkcl, skpv1, mod_p, vprime);
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//addition of h1 to vprime
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for (i = 0; i < SABER_N; i++) {
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vprime[i] = vprime[i] + h1;
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}
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// unpack message_received;
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for (j = 0; j < SABER_KEYBYTES; j++) {
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for (i = 0; i < 8; i++) {
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message[8 * j + i] = ((message_received[j] >> i) & 0x01);
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}
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}
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// message encoding
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for (i = 0; i < SABER_N; i++) {
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message[i] = (message[i] << (SABER_EP - 1));
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}
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for (k = 0; k < SABER_N; k++) {
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vprime[k] = ( (vprime[k] - message[k]) & (mod_p) ) >> (SABER_EP - SABER_ET);
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}
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PQCLEAN_LIGHTSABER_CLEAN_pack_3bit(msk_c, vprime);
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for (j = 0; j < SABER_SCALEBYTES_KEM; j++) {
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ciphertext[SABER_POLYVECCOMPRESSEDBYTES + j] = msk_c[j];
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}
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}
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void PQCLEAN_LIGHTSABER_CLEAN_indcpa_kem_dec(const unsigned char *sk, const unsigned char *ciphertext, unsigned char message_dec[]) {
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uint32_t i, j;
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uint16_t sksv[SABER_K][SABER_N]; //secret key of the server
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uint16_t pksv[SABER_K][SABER_N];
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uint8_t scale_ar[SABER_SCALEBYTES_KEM];
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uint16_t mod_p = SABER_P - 1;
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uint16_t v[SABER_N];
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uint16_t op[SABER_N];
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PQCLEAN_LIGHTSABER_CLEAN_BS2POLVEC(sk, sksv, SABER_Q); //sksv is the secret-key
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PQCLEAN_LIGHTSABER_CLEAN_BS2POLVEC(ciphertext, pksv, SABER_P); //pksv is the ciphertext
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// vector-vector scalar multiplication with mod p
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for (i = 0; i < SABER_N; i++) {
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v[i] = 0;
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}
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for (i = 0; i < SABER_K; i++) {
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for (j = 0; j < SABER_N; j++) {
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sksv[i][j] = sksv[i][j] & (mod_p);
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}
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}
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InnerProd(pksv, sksv, mod_p, v);
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//Extraction
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for (i = 0; i < SABER_SCALEBYTES_KEM; i++) {
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scale_ar[i] = ciphertext[SABER_POLYVECCOMPRESSEDBYTES + i];
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}
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PQCLEAN_LIGHTSABER_CLEAN_un_pack3bit(scale_ar, op);
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//addition of h1
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for (i = 0; i < SABER_N; i++) {
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v[i] = ( ( v[i] + h2 - (op[i] << (SABER_EP - SABER_ET)) ) & (mod_p) ) >> (SABER_EP - 1);
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}
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// pack decrypted message
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POL2MSG(v, message_dec);
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}
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static void MatrixVectorMul(polyvec *a, uint16_t skpv[SABER_K][SABER_N], uint16_t res[SABER_K][SABER_N], uint16_t mod, int16_t transpose) {
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uint16_t acc[SABER_N];
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int32_t i, j, k;
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if (transpose == 1) {
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for (i = 0; i < SABER_K; i++) {
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for (j = 0; j < SABER_K; j++) {
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PQCLEAN_LIGHTSABER_CLEAN_pol_mul((uint16_t *)&a[j].vec[i], skpv[j], acc, SABER_Q, SABER_N);
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for (k = 0; k < SABER_N; k++) {
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res[i][k] = res[i][k] + acc[k];
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res[i][k] = (res[i][k] & mod); //reduction mod p
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acc[k] = 0; //clear the accumulator
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}
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}
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}
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} else {
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for (i = 0; i < SABER_K; i++) {
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for (j = 0; j < SABER_K; j++) {
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PQCLEAN_LIGHTSABER_CLEAN_pol_mul((uint16_t *)&a[i].vec[j], skpv[j], acc, SABER_Q, SABER_N);
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for (k = 0; k < SABER_N; k++) {
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res[i][k] = res[i][k] + acc[k];
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res[i][k] = res[i][k] & mod; //reduction
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acc[k] = 0; //clear the accumulator
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}
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}
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}
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}
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}
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static void POL2MSG(const uint16_t *message_dec_unpacked, unsigned char *message_dec) {
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int32_t i, j;
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for (j = 0; j < SABER_KEYBYTES; j++) {
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message_dec[j] = 0;
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for (i = 0; i < 8; i++) {
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message_dec[j] = message_dec[j] | (uint8_t) (message_dec_unpacked[j * 8 + i] << i);
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}
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}
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}
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static void InnerProd(uint16_t pkcl[SABER_K][SABER_N], uint16_t skpv[SABER_K][SABER_N], uint16_t mod, uint16_t res[SABER_N]) {
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uint32_t j, k;
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uint16_t acc[SABER_N];
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// vector-vector scalar multiplication with mod p
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for (j = 0; j < SABER_K; j++) {
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PQCLEAN_LIGHTSABER_CLEAN_pol_mul(pkcl[j], skpv[j], acc, SABER_P, SABER_N);
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for (k = 0; k < SABER_N; k++) {
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res[k] = res[k] + acc[k];
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res[k] = res[k] & mod; //reduction
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acc[k] = 0; //clear the accumulator
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}
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}
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}
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