80 lines
3.4 KiB
C
80 lines
3.4 KiB
C
#include "bf_decoding.h"
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#include "gf2x_arith_mod_xPplusOne.h"
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#include <string.h>
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int PQCLEAN_LEDAKEMLT32_LEAKTIME_bf_decoding(DIGIT err[],
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const POSITION_T HtrPosOnes[N0][DV],
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const POSITION_T QtrPosOnes[N0][M],
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DIGIT privateSyndrome[],
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uint8_t secondIterThreshold) {
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DIGIT currSyndrome[NUM_DIGITS_GF2X_ELEMENT];
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uint8_t unsatParityChecks[N0 * P];
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POSITION_T currQBlkPos[M], currQBitPos[M];
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POSITION_T syndromePosToFlip, tmp;
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uint32_t correlation, corrt_syndrome_based;
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size_t currQoneIdx, endQblockIdx, currblockoffset;
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int check;
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int iteration = 0;
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do {
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PQCLEAN_LEDAKEMLT32_LEAKTIME_gf2x_copy(currSyndrome, privateSyndrome);
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memset(unsatParityChecks, 0x00, N0 * P * sizeof(uint8_t));
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for (size_t i = 0; i < N0; i++) {
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for (POSITION_T valueIdx = 0; valueIdx < P; valueIdx++) {
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for (size_t HtrOneIdx = 0; HtrOneIdx < DV; HtrOneIdx++) {
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tmp = (HtrPosOnes[i][HtrOneIdx] + valueIdx) >= P ?
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(HtrPosOnes[i][HtrOneIdx] + valueIdx) - P :
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(HtrPosOnes[i][HtrOneIdx] + valueIdx);
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if (PQCLEAN_LEDAKEMLT32_LEAKTIME_gf2x_get_coeff(currSyndrome, tmp)) {
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unsatParityChecks[i * P + valueIdx]++;
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}
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}
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}
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}
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/* iteration based threshold determination*/
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corrt_syndrome_based = iteration * secondIterThreshold + (1 - iteration) * B0;
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// Computation of correlation with a full Q matrix
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for (size_t i = 0; i < N0; i++) {
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for (POSITION_T j = 0; j < P; j++) {
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currQoneIdx = endQblockIdx = 0;
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correlation = 0;
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for (size_t blockIdx = 0; blockIdx < N0; blockIdx++) {
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endQblockIdx += qBlockWeights[blockIdx][i];
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currblockoffset = blockIdx * P;
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for (; currQoneIdx < endQblockIdx; currQoneIdx++) {
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tmp = QtrPosOnes[i][currQoneIdx] + j;
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tmp = tmp >= P ? tmp - P : tmp;
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currQBitPos[currQoneIdx] = tmp;
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currQBlkPos[currQoneIdx] = (POSITION_T)blockIdx;
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correlation += unsatParityChecks[tmp + currblockoffset];
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}
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}
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/* Correlation based flipping */
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if (correlation >= corrt_syndrome_based) {
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PQCLEAN_LEDAKEMLT32_LEAKTIME_gf2x_toggle_coeff(err + NUM_DIGITS_GF2X_ELEMENT * i, j);
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for (size_t v = 0; v < M; v++) {
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for (size_t HtrOneIdx = 0; HtrOneIdx < DV; HtrOneIdx++) {
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syndromePosToFlip = (HtrPosOnes[currQBlkPos[v]][HtrOneIdx] + currQBitPos[v]);
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syndromePosToFlip = syndromePosToFlip >= P ? syndromePosToFlip - P : syndromePosToFlip;
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PQCLEAN_LEDAKEMLT32_LEAKTIME_gf2x_toggle_coeff(privateSyndrome, syndromePosToFlip);
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}
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} // end for v
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} // end if
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} // end for j
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} // end for i
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iteration = iteration + 1;
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check = 0;
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while (check < NUM_DIGITS_GF2X_ELEMENT && privateSyndrome[check++] == 0) {};
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} while (iteration < ITERATIONS_MAX && check < NUM_DIGITS_GF2X_ELEMENT);
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return (check == NUM_DIGITS_GF2X_ELEMENT);
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}
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