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Simplify hqc-rmrs*/clean/reed_muller.c and fix potentially non-constant time behavior.

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John M. Schanck 2020-09-09 09:44:31 -04:00 committed by Kris Kwiatkowski
parent d5fd7d6d0c
commit 6c4abb23ec
3 changed files with 156 additions and 204 deletions
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120
crypto_kem/hqc-rmrs-128/clean/reed_muller.c
View File

@ -7,33 +7,19 @@
* Constant time implementation of Reed-Muller code RM(1,7) * Constant time implementation of Reed-Muller code RM(1,7)
*/ */
// setting this will help the compiler with auto vectorization
#undef ALIGNVECTORS
// number of repeated code words // number of repeated code words
#define MULTIPLICITY CEIL_DIVIDE(PARAM_N2, 128) #define MULTIPLICITY CEIL_DIVIDE(PARAM_N2, 128)
// codeword is 128 bits, seen multiple ways
typedef union {
uint8_t u8[16];
uint32_t u32[4];
} codeword
;
// Expanded codeword has a short for every bit, for internal calculations
typedef int16_t expandedCodeword[128]
;
// copy bit 0 into all bits of a 32 bit value // copy bit 0 into all bits of a 32 bit value
#define BIT0MASK(x) (int32_t)(-((x) & 1)) #define BIT0MASK(x) (-((x) & 1))
static void encode(codeword *word, int32_t message); static void encode(uint32_t *word, const uint8_t message);
static void hadamard(expandedCodeword *src, expandedCodeword *dst); static void hadamard(uint16_t src[128], uint16_t dst[128]);
static void expand_and_sum(expandedCodeword *dest, codeword src[]); static void expand_and_sum(uint16_t dest[128], const uint32_t src[4 * MULTIPLICITY]);
static int32_t find_peaks(expandedCodeword *transform); static uint8_t find_peaks(const uint16_t transform[128]);
@ -54,10 +40,10 @@ static int32_t find_peaks(expandedCodeword *transform);
* @param[out] word An RM(1,7) codeword * @param[out] word An RM(1,7) codeword
* @param[in] message A message * @param[in] message A message
*/ */
static void encode(codeword *word, int32_t message) { static void encode(uint32_t *word, uint8_t message) {
// the four parts of the word are identical // the four parts of the word are identical
// except for encoding bits 5 and 6 // except for encoding bits 5 and 6
int32_t first_word; uint32_t first_word;
// bit 7 flips all the bits, do that first to save work // bit 7 flips all the bits, do that first to save work
first_word = BIT0MASK(message >> 7); first_word = BIT0MASK(message >> 7);
// bits 0, 1, 2, 3, 4 are the same for all four longs // bits 0, 1, 2, 3, 4 are the same for all four longs
@ -68,14 +54,14 @@ static void encode(codeword *word, int32_t message) {
first_word ^= BIT0MASK(message >> 3) & 0xff00ff00; first_word ^= BIT0MASK(message >> 3) & 0xff00ff00;
first_word ^= BIT0MASK(message >> 4) & 0xffff0000; first_word ^= BIT0MASK(message >> 4) & 0xffff0000;
// we can store this in the first quarter // we can store this in the first quarter
word->u32[0] = first_word; word[0] = first_word;
// bit 5 flips entries 1 and 3; bit 6 flips 2 and 3 // bit 5 flips entries 1 and 3; bit 6 flips 2 and 3
first_word ^= BIT0MASK(message >> 5); first_word ^= BIT0MASK(message >> 5);
word->u32[1] = first_word; word[1] = first_word;
first_word ^= BIT0MASK(message >> 6); first_word ^= BIT0MASK(message >> 6);
word->u32[3] = first_word; word[3] = first_word;
first_word ^= BIT0MASK(message >> 5); first_word ^= BIT0MASK(message >> 5);
word->u32[2] = first_word; word[2] = first_word;
} }
@ -111,19 +97,20 @@ static void encode(codeword *word, int32_t message) {
* @param[out] src Structure that contain the expanded codeword * @param[out] src Structure that contain the expanded codeword
* @param[out] dst Structure that contain the expanded codeword * @param[out] dst Structure that contain the expanded codeword
*/ */
static void hadamard(expandedCodeword *src, expandedCodeword *dst) { static void hadamard(uint16_t src[128], uint16_t dst[128]) {
// the passes move data: // the passes move data:
// src -> dst -> src -> dst -> src -> dst -> src -> dst // src -> dst -> src -> dst -> src -> dst -> src -> dst
// using p1 and p2 alternately // using p1 and p2 alternately
expandedCodeword *p1 = src; uint16_t *p1 = src;
expandedCodeword *p2 = dst; uint16_t *p2 = dst;
for (int32_t pass = 0 ; pass < 7 ; pass++) { uint16_t *p3;
for (int32_t i = 0 ; i < 64 ; i++) { for (uint32_t pass = 0 ; pass < 7 ; pass++) {
(*p2)[i] = (*p1)[2 * i] + (*p1)[2 * i + 1]; for (uint32_t i = 0 ; i < 64 ; i++) {
(*p2)[i + 64] = (*p1)[2 * i] - (*p1)[2 * i + 1]; p2[i] = p1[2 * i] + p1[2 * i + 1];
p2[i + 64] = p1[2 * i] - p1[2 * i + 1];
} }
// swap p1, p2 for next round // swap p1, p2 for next round
expandedCodeword *p3 = p1; p3 = p1;
p1 = p2; p1 = p2;
p2 = p3; p2 = p3;
} }
@ -144,18 +131,18 @@ static void hadamard(expandedCodeword *src, expandedCodeword *dst) {
* @param[out] dest Structure that contain the expanded codeword * @param[out] dest Structure that contain the expanded codeword
* @param[in] src Structure that contain the codeword * @param[in] src Structure that contain the codeword
*/ */
static void expand_and_sum(expandedCodeword *dest, codeword src[]) { static void expand_and_sum(uint16_t dest[128], const uint32_t src[4 * MULTIPLICITY]) {
// start with the first copy // start with the first copy
for (int32_t part = 0 ; part < 4 ; part++) { for (uint32_t part = 0 ; part < 4 ; part++) {
for (int32_t bit = 0 ; bit < 32 ; bit++) { for (uint32_t bit = 0 ; bit < 32 ; bit++) {
(*dest)[part * 32 + bit] = src[0].u32[part] >> bit & 1; dest[part * 32 + bit] = (uint16_t) ((src[part] >> bit) & 1);
} }
} }
// sum the rest of the copies // sum the rest of the copies
for (int32_t copy = 1 ; copy < MULTIPLICITY ; copy++) { for (uint32_t copy = 1 ; copy < MULTIPLICITY ; copy++) {
for (int32_t part = 0 ; part < 4 ; part++) { for (uint32_t part = 0 ; part < 4 ; part++) {
for (int32_t bit = 0 ; bit < 32 ; bit++) { for (uint32_t bit = 0 ; bit < 32 ; bit++) {
(*dest)[part * 32 + bit] += src[copy].u32[part] >> bit & 1; dest[part * 32 + bit] += (uint16_t) ((src[4 * copy + part] >> bit) & 1);
} }
} }
} }
@ -172,27 +159,26 @@ static void expand_and_sum(expandedCodeword *dest, codeword src[]) {
* in the lowest 7 bits it taken * in the lowest 7 bits it taken
* @param[in] transform Structure that contain the expanded codeword * @param[in] transform Structure that contain the expanded codeword
*/ */
static int32_t find_peaks(expandedCodeword *transform) { static uint8_t find_peaks(const uint16_t transform[128]) {
int32_t peak_abs_value = 0; uint16_t peak_abs = 0;
int32_t peak_value = 0; uint16_t peak = 0;
int32_t peak_pos = 0; uint16_t pos = 0;
for (int32_t i = 0 ; i < 128 ; i++) { uint16_t t, abs, mask;
// get absolute value for (uint16_t i = 0 ; i < 128 ; i++) {
int32_t t = (*transform)[i]; t = transform[i];
int32_t pos_mask = -(t > 0); abs = t ^ ((-(t >> 15)) & (t ^ -t)); // t = abs(t)
int32_t absolute = (pos_mask & t) | (~pos_mask & -t); mask = -(((uint16_t)(peak_abs - abs)) >> 15);
// all compilers nowadays compile with a conditional move peak ^= mask & (peak ^ t);
peak_value = absolute > peak_abs_value ? t : peak_value; pos ^= mask & (pos ^ i);
peak_pos = absolute > peak_abs_value ? i : peak_pos; peak_abs ^= mask & (peak_abs ^ abs);
peak_abs_value = absolute > peak_abs_value ? absolute : peak_abs_value;
} }
// set bit 7 pos |= 128 & ((peak >> 15) - 1);
peak_pos |= 128 * (peak_value > 0); return (uint8_t) pos;
return peak_pos;
} }
/** /**
* @brief Encodes the received word * @brief Encodes the received word
* *
@ -204,15 +190,13 @@ static int32_t find_peaks(expandedCodeword *transform) {
*/ */
void PQCLEAN_HQCRMRS128_CLEAN_reed_muller_encode(uint64_t *cdw, const uint64_t *msg) { void PQCLEAN_HQCRMRS128_CLEAN_reed_muller_encode(uint64_t *cdw, const uint64_t *msg) {
uint8_t *message_array = (uint8_t *) msg; uint8_t *message_array = (uint8_t *) msg;
codeword *codeArray = (codeword *) cdw; uint32_t *codeArray = (uint32_t *) cdw;
for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) { for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) {
// fill entries i * MULTIPLICITY to (i+1) * MULTIPLICITY
int32_t pos = i * MULTIPLICITY;
// encode first word // encode first word
encode(&codeArray[pos], message_array[i]); encode(&codeArray[4 * i * MULTIPLICITY], message_array[i]);
// copy to other identical codewords // copy to other identical codewords
for (size_t copy = 1 ; copy < MULTIPLICITY ; copy++) { for (size_t copy = 1 ; copy < MULTIPLICITY ; copy++) {
memcpy(&codeArray[pos + copy], &codeArray[pos], sizeof(codeword)); memcpy(&codeArray[4 * i * MULTIPLICITY + 4 * copy], &codeArray[4 * i * MULTIPLICITY], 4 * sizeof(uint32_t));
} }
} }
} }
@ -230,17 +214,17 @@ void PQCLEAN_HQCRMRS128_CLEAN_reed_muller_encode(uint64_t *cdw, const uint64_t *
*/ */
void PQCLEAN_HQCRMRS128_CLEAN_reed_muller_decode(uint64_t *msg, const uint64_t *cdw) { void PQCLEAN_HQCRMRS128_CLEAN_reed_muller_decode(uint64_t *msg, const uint64_t *cdw) {
uint8_t *message_array = (uint8_t *) msg; uint8_t *message_array = (uint8_t *) msg;
codeword *codeArray = (codeword *) cdw; uint32_t *codeArray = (uint32_t *) cdw;
expandedCodeword expanded; uint16_t expanded[128];
uint16_t transform[128];
for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) { for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) {
// collect the codewords // collect the codewords
expand_and_sum(&expanded, &codeArray[i * MULTIPLICITY]); expand_and_sum(expanded, &codeArray[4 * i * MULTIPLICITY]);
// apply hadamard transform // apply hadamard transform
expandedCodeword transform; hadamard(expanded, transform);
hadamard(&expanded, &transform);
// fix the first entry to get the half Hadamard transform // fix the first entry to get the half Hadamard transform
transform[0] -= 64 * MULTIPLICITY; transform[0] -= 64 * MULTIPLICITY;
// finish the decoding // finish the decoding
message_array[i] = find_peaks(&transform); message_array[i] = find_peaks(transform);
} }
} }

120
crypto_kem/hqc-rmrs-192/clean/reed_muller.c
View File

@ -7,33 +7,19 @@
* Constant time implementation of Reed-Muller code RM(1,7) * Constant time implementation of Reed-Muller code RM(1,7)
*/ */
// setting this will help the compiler with auto vectorization
#undef ALIGNVECTORS
// number of repeated code words // number of repeated code words
#define MULTIPLICITY CEIL_DIVIDE(PARAM_N2, 128) #define MULTIPLICITY CEIL_DIVIDE(PARAM_N2, 128)
// codeword is 128 bits, seen multiple ways
typedef union {
uint8_t u8[16];
uint32_t u32[4];
} codeword
;
// Expanded codeword has a short for every bit, for internal calculations
typedef int16_t expandedCodeword[128]
;
// copy bit 0 into all bits of a 32 bit value // copy bit 0 into all bits of a 32 bit value
#define BIT0MASK(x) (int32_t)(-((x) & 1)) #define BIT0MASK(x) (-((x) & 1))
static void encode(codeword *word, int32_t message); static void encode(uint32_t *word, const uint8_t message);
static void hadamard(expandedCodeword *src, expandedCodeword *dst); static void hadamard(uint16_t src[128], uint16_t dst[128]);
static void expand_and_sum(expandedCodeword *dest, codeword src[]); static void expand_and_sum(uint16_t dest[128], const uint32_t src[4 * MULTIPLICITY]);
static int32_t find_peaks(expandedCodeword *transform); static uint8_t find_peaks(const uint16_t transform[128]);
@ -54,10 +40,10 @@ static int32_t find_peaks(expandedCodeword *transform);
* @param[out] word An RM(1,7) codeword * @param[out] word An RM(1,7) codeword
* @param[in] message A message * @param[in] message A message
*/ */
static void encode(codeword *word, int32_t message) { static void encode(uint32_t *word, uint8_t message) {
// the four parts of the word are identical // the four parts of the word are identical
// except for encoding bits 5 and 6 // except for encoding bits 5 and 6
int32_t first_word; uint32_t first_word;
// bit 7 flips all the bits, do that first to save work // bit 7 flips all the bits, do that first to save work
first_word = BIT0MASK(message >> 7); first_word = BIT0MASK(message >> 7);
// bits 0, 1, 2, 3, 4 are the same for all four longs // bits 0, 1, 2, 3, 4 are the same for all four longs
@ -68,14 +54,14 @@ static void encode(codeword *word, int32_t message) {
first_word ^= BIT0MASK(message >> 3) & 0xff00ff00; first_word ^= BIT0MASK(message >> 3) & 0xff00ff00;
first_word ^= BIT0MASK(message >> 4) & 0xffff0000; first_word ^= BIT0MASK(message >> 4) & 0xffff0000;
// we can store this in the first quarter // we can store this in the first quarter
word->u32[0] = first_word; word[0] = first_word;
// bit 5 flips entries 1 and 3; bit 6 flips 2 and 3 // bit 5 flips entries 1 and 3; bit 6 flips 2 and 3
first_word ^= BIT0MASK(message >> 5); first_word ^= BIT0MASK(message >> 5);
word->u32[1] = first_word; word[1] = first_word;
first_word ^= BIT0MASK(message >> 6); first_word ^= BIT0MASK(message >> 6);
word->u32[3] = first_word; word[3] = first_word;
first_word ^= BIT0MASK(message >> 5); first_word ^= BIT0MASK(message >> 5);
word->u32[2] = first_word; word[2] = first_word;
} }
@ -111,19 +97,20 @@ static void encode(codeword *word, int32_t message) {
* @param[out] src Structure that contain the expanded codeword * @param[out] src Structure that contain the expanded codeword
* @param[out] dst Structure that contain the expanded codeword * @param[out] dst Structure that contain the expanded codeword
*/ */
static void hadamard(expandedCodeword *src, expandedCodeword *dst) { static void hadamard(uint16_t src[128], uint16_t dst[128]) {
// the passes move data: // the passes move data:
// src -> dst -> src -> dst -> src -> dst -> src -> dst // src -> dst -> src -> dst -> src -> dst -> src -> dst
// using p1 and p2 alternately // using p1 and p2 alternately
expandedCodeword *p1 = src; uint16_t *p1 = src;
expandedCodeword *p2 = dst; uint16_t *p2 = dst;
for (int32_t pass = 0 ; pass < 7 ; pass++) { uint16_t *p3;
for (int32_t i = 0 ; i < 64 ; i++) { for (uint32_t pass = 0 ; pass < 7 ; pass++) {
(*p2)[i] = (*p1)[2 * i] + (*p1)[2 * i + 1]; for (uint32_t i = 0 ; i < 64 ; i++) {
(*p2)[i + 64] = (*p1)[2 * i] - (*p1)[2 * i + 1]; p2[i] = p1[2 * i] + p1[2 * i + 1];
p2[i + 64] = p1[2 * i] - p1[2 * i + 1];
} }
// swap p1, p2 for next round // swap p1, p2 for next round
expandedCodeword *p3 = p1; p3 = p1;
p1 = p2; p1 = p2;
p2 = p3; p2 = p3;
} }
@ -144,18 +131,18 @@ static void hadamard(expandedCodeword *src, expandedCodeword *dst) {
* @param[out] dest Structure that contain the expanded codeword * @param[out] dest Structure that contain the expanded codeword
* @param[in] src Structure that contain the codeword * @param[in] src Structure that contain the codeword
*/ */
static void expand_and_sum(expandedCodeword *dest, codeword src[]) { static void expand_and_sum(uint16_t dest[128], const uint32_t src[4 * MULTIPLICITY]) {
// start with the first copy // start with the first copy
for (int32_t part = 0 ; part < 4 ; part++) { for (uint32_t part = 0 ; part < 4 ; part++) {
for (int32_t bit = 0 ; bit < 32 ; bit++) { for (uint32_t bit = 0 ; bit < 32 ; bit++) {
(*dest)[part * 32 + bit] = src[0].u32[part] >> bit & 1; dest[part * 32 + bit] = (uint16_t) ((src[part] >> bit) & 1);
} }
} }
// sum the rest of the copies // sum the rest of the copies
for (int32_t copy = 1 ; copy < MULTIPLICITY ; copy++) { for (uint32_t copy = 1 ; copy < MULTIPLICITY ; copy++) {
for (int32_t part = 0 ; part < 4 ; part++) { for (uint32_t part = 0 ; part < 4 ; part++) {
for (int32_t bit = 0 ; bit < 32 ; bit++) { for (uint32_t bit = 0 ; bit < 32 ; bit++) {
(*dest)[part * 32 + bit] += src[copy].u32[part] >> bit & 1; dest[part * 32 + bit] += (uint16_t) ((src[4 * copy + part] >> bit) & 1);
} }
} }
} }
@ -172,27 +159,26 @@ static void expand_and_sum(expandedCodeword *dest, codeword src[]) {
* in the lowest 7 bits it taken * in the lowest 7 bits it taken
* @param[in] transform Structure that contain the expanded codeword * @param[in] transform Structure that contain the expanded codeword
*/ */
static int32_t find_peaks(expandedCodeword *transform) { static uint8_t find_peaks(const uint16_t transform[128]) {
int32_t peak_abs_value = 0; uint16_t peak_abs = 0;
int32_t peak_value = 0; uint16_t peak = 0;
int32_t peak_pos = 0; uint16_t pos = 0;
for (int32_t i = 0 ; i < 128 ; i++) { uint16_t t, abs, mask;
// get absolute value for (uint16_t i = 0 ; i < 128 ; i++) {
int32_t t = (*transform)[i]; t = transform[i];
int32_t pos_mask = -(t > 0); abs = t ^ ((-(t >> 15)) & (t ^ -t)); // t = abs(t)
int32_t absolute = (pos_mask & t) | (~pos_mask & -t); mask = -(((uint16_t)(peak_abs - abs)) >> 15);
// all compilers nowadays compile with a conditional move peak ^= mask & (peak ^ t);
peak_value = absolute > peak_abs_value ? t : peak_value; pos ^= mask & (pos ^ i);
peak_pos = absolute > peak_abs_value ? i : peak_pos; peak_abs ^= mask & (peak_abs ^ abs);
peak_abs_value = absolute > peak_abs_value ? absolute : peak_abs_value;
} }
// set bit 7 pos |= 128 & ((peak >> 15) - 1);
peak_pos |= 128 * (peak_value > 0); return (uint8_t) pos;
return peak_pos;
} }
/** /**
* @brief Encodes the received word * @brief Encodes the received word
* *
@ -204,15 +190,13 @@ static int32_t find_peaks(expandedCodeword *transform) {
*/ */
void PQCLEAN_HQCRMRS192_CLEAN_reed_muller_encode(uint64_t *cdw, const uint64_t *msg) { void PQCLEAN_HQCRMRS192_CLEAN_reed_muller_encode(uint64_t *cdw, const uint64_t *msg) {
uint8_t *message_array = (uint8_t *) msg; uint8_t *message_array = (uint8_t *) msg;
codeword *codeArray = (codeword *) cdw; uint32_t *codeArray = (uint32_t *) cdw;
for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) { for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) {
// fill entries i * MULTIPLICITY to (i+1) * MULTIPLICITY
int32_t pos = i * MULTIPLICITY;
// encode first word // encode first word
encode(&codeArray[pos], message_array[i]); encode(&codeArray[4 * i * MULTIPLICITY], message_array[i]);
// copy to other identical codewords // copy to other identical codewords
for (size_t copy = 1 ; copy < MULTIPLICITY ; copy++) { for (size_t copy = 1 ; copy < MULTIPLICITY ; copy++) {
memcpy(&codeArray[pos + copy], &codeArray[pos], sizeof(codeword)); memcpy(&codeArray[4 * i * MULTIPLICITY + 4 * copy], &codeArray[4 * i * MULTIPLICITY], 4 * sizeof(uint32_t));
} }
} }
} }
@ -230,17 +214,17 @@ void PQCLEAN_HQCRMRS192_CLEAN_reed_muller_encode(uint64_t *cdw, const uint64_t *
*/ */
void PQCLEAN_HQCRMRS192_CLEAN_reed_muller_decode(uint64_t *msg, const uint64_t *cdw) { void PQCLEAN_HQCRMRS192_CLEAN_reed_muller_decode(uint64_t *msg, const uint64_t *cdw) {
uint8_t *message_array = (uint8_t *) msg; uint8_t *message_array = (uint8_t *) msg;
codeword *codeArray = (codeword *) cdw; uint32_t *codeArray = (uint32_t *) cdw;
expandedCodeword expanded; uint16_t expanded[128];
uint16_t transform[128];
for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) { for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) {
// collect the codewords // collect the codewords
expand_and_sum(&expanded, &codeArray[i * MULTIPLICITY]); expand_and_sum(expanded, &codeArray[4 * i * MULTIPLICITY]);
// apply hadamard transform // apply hadamard transform
expandedCodeword transform; hadamard(expanded, transform);
hadamard(&expanded, &transform);
// fix the first entry to get the half Hadamard transform // fix the first entry to get the half Hadamard transform
transform[0] -= 64 * MULTIPLICITY; transform[0] -= 64 * MULTIPLICITY;
// finish the decoding // finish the decoding
message_array[i] = find_peaks(&transform); message_array[i] = find_peaks(transform);
} }
} }

120
crypto_kem/hqc-rmrs-256/clean/reed_muller.c
View File

@ -7,33 +7,19 @@
* Constant time implementation of Reed-Muller code RM(1,7) * Constant time implementation of Reed-Muller code RM(1,7)
*/ */
// setting this will help the compiler with auto vectorization
#undef ALIGNVECTORS
// number of repeated code words // number of repeated code words
#define MULTIPLICITY CEIL_DIVIDE(PARAM_N2, 128) #define MULTIPLICITY CEIL_DIVIDE(PARAM_N2, 128)
// codeword is 128 bits, seen multiple ways
typedef union {
uint8_t u8[16];
uint32_t u32[4];
} codeword
;
// Expanded codeword has a short for every bit, for internal calculations
typedef int16_t expandedCodeword[128]
;
// copy bit 0 into all bits of a 32 bit value // copy bit 0 into all bits of a 32 bit value
#define BIT0MASK(x) (int32_t)(-((x) & 1)) #define BIT0MASK(x) (-((x) & 1))
static void encode(codeword *word, int32_t message); static void encode(uint32_t *word, const uint8_t message);
static void hadamard(expandedCodeword *src, expandedCodeword *dst); static void hadamard(uint16_t src[128], uint16_t dst[128]);
static void expand_and_sum(expandedCodeword *dest, codeword src[]); static void expand_and_sum(uint16_t dest[128], const uint32_t src[4 * MULTIPLICITY]);
static int32_t find_peaks(expandedCodeword *transform); static uint8_t find_peaks(const uint16_t transform[128]);
@ -54,10 +40,10 @@ static int32_t find_peaks(expandedCodeword *transform);
* @param[out] word An RM(1,7) codeword * @param[out] word An RM(1,7) codeword
* @param[in] message A message * @param[in] message A message
*/ */
static void encode(codeword *word, int32_t message) { static void encode(uint32_t *word, uint8_t message) {
// the four parts of the word are identical // the four parts of the word are identical
// except for encoding bits 5 and 6 // except for encoding bits 5 and 6
int32_t first_word; uint32_t first_word;
// bit 7 flips all the bits, do that first to save work // bit 7 flips all the bits, do that first to save work
first_word = BIT0MASK(message >> 7); first_word = BIT0MASK(message >> 7);
// bits 0, 1, 2, 3, 4 are the same for all four longs // bits 0, 1, 2, 3, 4 are the same for all four longs
@ -68,14 +54,14 @@ static void encode(codeword *word, int32_t message) {
first_word ^= BIT0MASK(message >> 3) & 0xff00ff00; first_word ^= BIT0MASK(message >> 3) & 0xff00ff00;
first_word ^= BIT0MASK(message >> 4) & 0xffff0000; first_word ^= BIT0MASK(message >> 4) & 0xffff0000;
// we can store this in the first quarter // we can store this in the first quarter
word->u32[0] = first_word; word[0] = first_word;
// bit 5 flips entries 1 and 3; bit 6 flips 2 and 3 // bit 5 flips entries 1 and 3; bit 6 flips 2 and 3
first_word ^= BIT0MASK(message >> 5); first_word ^= BIT0MASK(message >> 5);
word->u32[1] = first_word; word[1] = first_word;
first_word ^= BIT0MASK(message >> 6); first_word ^= BIT0MASK(message >> 6);
word->u32[3] = first_word; word[3] = first_word;
first_word ^= BIT0MASK(message >> 5); first_word ^= BIT0MASK(message >> 5);
word->u32[2] = first_word; word[2] = first_word;
} }
@ -111,19 +97,20 @@ static void encode(codeword *word, int32_t message) {
* @param[out] src Structure that contain the expanded codeword * @param[out] src Structure that contain the expanded codeword
* @param[out] dst Structure that contain the expanded codeword * @param[out] dst Structure that contain the expanded codeword
*/ */
static void hadamard(expandedCodeword *src, expandedCodeword *dst) { static void hadamard(uint16_t src[128], uint16_t dst[128]) {
// the passes move data: // the passes move data:
// src -> dst -> src -> dst -> src -> dst -> src -> dst // src -> dst -> src -> dst -> src -> dst -> src -> dst
// using p1 and p2 alternately // using p1 and p2 alternately
expandedCodeword *p1 = src; uint16_t *p1 = src;
expandedCodeword *p2 = dst; uint16_t *p2 = dst;
for (int32_t pass = 0 ; pass < 7 ; pass++) { uint16_t *p3;
for (int32_t i = 0 ; i < 64 ; i++) { for (uint32_t pass = 0 ; pass < 7 ; pass++) {
(*p2)[i] = (*p1)[2 * i] + (*p1)[2 * i + 1]; for (uint32_t i = 0 ; i < 64 ; i++) {
(*p2)[i + 64] = (*p1)[2 * i] - (*p1)[2 * i + 1]; p2[i] = p1[2 * i] + p1[2 * i + 1];
p2[i + 64] = p1[2 * i] - p1[2 * i + 1];
} }
// swap p1, p2 for next round // swap p1, p2 for next round
expandedCodeword *p3 = p1; p3 = p1;
p1 = p2; p1 = p2;
p2 = p3; p2 = p3;
} }
@ -144,18 +131,18 @@ static void hadamard(expandedCodeword *src, expandedCodeword *dst) {
* @param[out] dest Structure that contain the expanded codeword * @param[out] dest Structure that contain the expanded codeword
* @param[in] src Structure that contain the codeword * @param[in] src Structure that contain the codeword
*/ */
static void expand_and_sum(expandedCodeword *dest, codeword src[]) { static void expand_and_sum(uint16_t dest[128], const uint32_t src[4 * MULTIPLICITY]) {
// start with the first copy // start with the first copy
for (int32_t part = 0 ; part < 4 ; part++) { for (uint32_t part = 0 ; part < 4 ; part++) {
for (int32_t bit = 0 ; bit < 32 ; bit++) { for (uint32_t bit = 0 ; bit < 32 ; bit++) {
(*dest)[part * 32 + bit] = src[0].u32[part] >> bit & 1; dest[part * 32 + bit] = (uint16_t) ((src[part] >> bit) & 1);
} }
} }
// sum the rest of the copies // sum the rest of the copies
for (int32_t copy = 1 ; copy < MULTIPLICITY ; copy++) { for (uint32_t copy = 1 ; copy < MULTIPLICITY ; copy++) {
for (int32_t part = 0 ; part < 4 ; part++) { for (uint32_t part = 0 ; part < 4 ; part++) {
for (int32_t bit = 0 ; bit < 32 ; bit++) { for (uint32_t bit = 0 ; bit < 32 ; bit++) {
(*dest)[part * 32 + bit] += src[copy].u32[part] >> bit & 1; dest[part * 32 + bit] += (uint16_t) ((src[4 * copy + part] >> bit) & 1);
} }
} }
} }
@ -172,27 +159,26 @@ static void expand_and_sum(expandedCodeword *dest, codeword src[]) {
* in the lowest 7 bits it taken * in the lowest 7 bits it taken
* @param[in] transform Structure that contain the expanded codeword * @param[in] transform Structure that contain the expanded codeword
*/ */
static int32_t find_peaks(expandedCodeword *transform) { static uint8_t find_peaks(const uint16_t transform[128]) {
int32_t peak_abs_value = 0; uint16_t peak_abs = 0;
int32_t peak_value = 0; uint16_t peak = 0;
int32_t peak_pos = 0; uint16_t pos = 0;
for (int32_t i = 0 ; i < 128 ; i++) { uint16_t t, abs, mask;
// get absolute value for (uint16_t i = 0 ; i < 128 ; i++) {
int32_t t = (*transform)[i]; t = transform[i];
int32_t pos_mask = -(t > 0); abs = t ^ ((-(t >> 15)) & (t ^ -t)); // t = abs(t)
int32_t absolute = (pos_mask & t) | (~pos_mask & -t); mask = -(((uint16_t)(peak_abs - abs)) >> 15);
// all compilers nowadays compile with a conditional move peak ^= mask & (peak ^ t);
peak_value = absolute > peak_abs_value ? t : peak_value; pos ^= mask & (pos ^ i);
peak_pos = absolute > peak_abs_value ? i : peak_pos; peak_abs ^= mask & (peak_abs ^ abs);
peak_abs_value = absolute > peak_abs_value ? absolute : peak_abs_value;
} }
// set bit 7 pos |= 128 & ((peak >> 15) - 1);
peak_pos |= 128 * (peak_value > 0); return (uint8_t) pos;
return peak_pos;
} }
/** /**
* @brief Encodes the received word * @brief Encodes the received word
* *
@ -204,15 +190,13 @@ static int32_t find_peaks(expandedCodeword *transform) {
*/ */
void PQCLEAN_HQCRMRS256_CLEAN_reed_muller_encode(uint64_t *cdw, const uint64_t *msg) { void PQCLEAN_HQCRMRS256_CLEAN_reed_muller_encode(uint64_t *cdw, const uint64_t *msg) {
uint8_t *message_array = (uint8_t *) msg; uint8_t *message_array = (uint8_t *) msg;
codeword *codeArray = (codeword *) cdw; uint32_t *codeArray = (uint32_t *) cdw;
for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) { for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) {
// fill entries i * MULTIPLICITY to (i+1) * MULTIPLICITY
int32_t pos = i * MULTIPLICITY;
// encode first word // encode first word
encode(&codeArray[pos], message_array[i]); encode(&codeArray[4 * i * MULTIPLICITY], message_array[i]);
// copy to other identical codewords // copy to other identical codewords
for (size_t copy = 1 ; copy < MULTIPLICITY ; copy++) { for (size_t copy = 1 ; copy < MULTIPLICITY ; copy++) {
memcpy(&codeArray[pos + copy], &codeArray[pos], sizeof(codeword)); memcpy(&codeArray[4 * i * MULTIPLICITY + 4 * copy], &codeArray[4 * i * MULTIPLICITY], 4 * sizeof(uint32_t));
} }
} }
} }
@ -230,17 +214,17 @@ void PQCLEAN_HQCRMRS256_CLEAN_reed_muller_encode(uint64_t *cdw, const uint64_t *
*/ */
void PQCLEAN_HQCRMRS256_CLEAN_reed_muller_decode(uint64_t *msg, const uint64_t *cdw) { void PQCLEAN_HQCRMRS256_CLEAN_reed_muller_decode(uint64_t *msg, const uint64_t *cdw) {
uint8_t *message_array = (uint8_t *) msg; uint8_t *message_array = (uint8_t *) msg;
codeword *codeArray = (codeword *) cdw; uint32_t *codeArray = (uint32_t *) cdw;
expandedCodeword expanded; uint16_t expanded[128];
uint16_t transform[128];
for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) { for (size_t i = 0 ; i < VEC_N1_SIZE_BYTES ; i++) {
// collect the codewords // collect the codewords
expand_and_sum(&expanded, &codeArray[i * MULTIPLICITY]); expand_and_sum(expanded, &codeArray[4 * i * MULTIPLICITY]);
// apply hadamard transform // apply hadamard transform
expandedCodeword transform; hadamard(expanded, transform);
hadamard(&expanded, &transform);
// fix the first entry to get the half Hadamard transform // fix the first entry to get the half Hadamard transform
transform[0] -= 64 * MULTIPLICITY; transform[0] -= 64 * MULTIPLICITY;
// finish the decoding // finish the decoding
message_array[i] = find_peaks(&transform); message_array[i] = find_peaks(transform);
} }
} }