158 lines
6.2 KiB
C
158 lines
6.2 KiB
C
#include "api.h"
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#include "niederreiter.h"
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#include "randombytes.h"
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#include "rng.h"
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#include "utils.h"
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#include <string.h>
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#define pack_ct(sk_bytes, ct) PQCLEAN_LEDAKEMLT52_LEAKTIME_gf2x_tobytes(sk_bytes, ct);
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#define unpack_ct(ct, ct_bytes) PQCLEAN_LEDAKEMLT52_LEAKTIME_gf2x_frombytes(ct, ct_bytes)
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static void pack_pk(uint8_t *pk_bytes, publicKeyNiederreiter_t *pk) {
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for (size_t i = 0; i < N0 - 1; i++) {
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PQCLEAN_LEDAKEMLT52_LEAKTIME_gf2x_tobytes(pk_bytes + i * NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B,
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pk->Mtr + i * NUM_DIGITS_GF2X_ELEMENT);
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}
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}
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static void unpack_pk(publicKeyNiederreiter_t *pk, const uint8_t *pk_bytes) {
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for (size_t i = 0; i < N0 - 1; i++) {
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PQCLEAN_LEDAKEMLT52_LEAKTIME_gf2x_frombytes(pk->Mtr + i * NUM_DIGITS_GF2X_ELEMENT,
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pk_bytes + i * NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B);
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}
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}
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static void pack_error(uint8_t *error_bytes, DIGIT *error_digits) {
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size_t i;
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for (i = 0; i < N0; i++) {
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PQCLEAN_LEDAKEMLT52_LEAKTIME_gf2x_tobytes(error_bytes + i * NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B,
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error_digits + i * NUM_DIGITS_GF2X_ELEMENT);
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}
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}
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/* IND-CCA2 Keygen */
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int PQCLEAN_LEDAKEMLT52_LEAKTIME_crypto_kem_keypair(uint8_t *pk, uint8_t *sk) {
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publicKeyNiederreiter_t niederreiter_pk;
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PQCLEAN_LEDAKEMLT52_LEAKTIME_niederreiter_keygen(&niederreiter_pk, (privateKeyNiederreiter_t *) sk);
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pack_pk(pk, &niederreiter_pk);
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return 0;
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}
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/* IND-CCA2 Encapsulation */
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int PQCLEAN_LEDAKEMLT52_LEAKTIME_crypto_kem_enc(uint8_t *ct, uint8_t *ss, const uint8_t *pk) {
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publicKeyNiederreiter_t niederreiter_pk;
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DIGIT syndrome[NUM_DIGITS_GF2X_ELEMENT];
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AES_XOF_struct hashedAndTruncatedSeed_expander;
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POSITION_T errorPos[NUM_ERRORS_T];
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DIGIT error_vector[N0 * NUM_DIGITS_GF2X_ELEMENT];
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uint8_t error_bytes[N0 * NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B];
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uint8_t seed[TRNG_BYTE_LENGTH];
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uint8_t ss_input[2 * TRNG_BYTE_LENGTH] = {0};
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uint8_t hashedSeed[HASH_BYTE_LENGTH];
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uint8_t hashedAndTruncatedSeed[TRNG_BYTE_LENGTH] = {0};
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uint8_t hashedErrorVector[HASH_BYTE_LENGTH];
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uint8_t hashedAndTruncatedErrorVector[TRNG_BYTE_LENGTH] = {0};
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uint8_t maskedSeed[TRNG_BYTE_LENGTH];
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unpack_pk(&niederreiter_pk, pk);
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randombytes(seed, TRNG_BYTE_LENGTH);
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memcpy(ss_input, seed, TRNG_BYTE_LENGTH);
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HASH_FUNCTION(ss, ss_input, 2 * TRNG_BYTE_LENGTH);
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HASH_FUNCTION(hashedSeed, seed, TRNG_BYTE_LENGTH);
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memcpy(hashedAndTruncatedSeed, hashedSeed, TRNG_BYTE_LENGTH);
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memset(&hashedAndTruncatedSeed_expander, 0x00, sizeof(AES_XOF_struct));
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PQCLEAN_LEDAKEMLT52_LEAKTIME_seedexpander_from_trng(&hashedAndTruncatedSeed_expander, hashedAndTruncatedSeed);
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PQCLEAN_LEDAKEMLT52_LEAKTIME_rand_error_pos(errorPos, &hashedAndTruncatedSeed_expander);
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PQCLEAN_LEDAKEMLT52_LEAKTIME_expand_error(error_vector, errorPos);
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pack_error(error_bytes, error_vector);
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HASH_FUNCTION(hashedErrorVector, error_bytes, (N0 * NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B));
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memcpy(hashedAndTruncatedErrorVector, hashedErrorVector, TRNG_BYTE_LENGTH);
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for (size_t i = 0; i < TRNG_BYTE_LENGTH; ++i) {
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maskedSeed[i] = seed[i] ^ hashedAndTruncatedErrorVector[i];
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}
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PQCLEAN_LEDAKEMLT52_LEAKTIME_niederreiter_encrypt(syndrome,
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(const publicKeyNiederreiter_t *) &niederreiter_pk, error_vector);
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pack_ct(ct, syndrome);
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memcpy(ct + (NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B), maskedSeed, TRNG_BYTE_LENGTH);
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return 0;
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}
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/* IND-CCA2 Decapsulation */
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int PQCLEAN_LEDAKEMLT52_LEAKTIME_crypto_kem_dec(uint8_t *ss, const uint8_t *ct, const uint8_t *sk) {
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DIGIT syndrome[NUM_DIGITS_GF2X_ELEMENT];
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AES_XOF_struct hashedAndTruncatedSeed_expander;
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POSITION_T reconstructed_errorPos[NUM_ERRORS_T];
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DIGIT reconstructed_error_vector[N0 * NUM_DIGITS_GF2X_ELEMENT];
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DIGIT decoded_error_vector[N0 * NUM_DIGITS_GF2X_ELEMENT];
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uint8_t decoded_error_bytes[N0 * NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B];
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uint8_t hashedErrorVector[HASH_BYTE_LENGTH];
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uint8_t hashedAndTruncatedErrorVector[TRNG_BYTE_LENGTH] = {0};
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uint8_t decoded_seed[TRNG_BYTE_LENGTH];
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uint8_t hashed_decoded_seed[HASH_BYTE_LENGTH];
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uint8_t hashedAndTruncated_decoded_seed[TRNG_BYTE_LENGTH] = {0};
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uint8_t ss_input[2 * TRNG_BYTE_LENGTH], tail[TRNG_BYTE_LENGTH] = {0};
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int decode_ok, decrypt_ok, equal;
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unpack_ct(syndrome, ct);
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decode_ok = PQCLEAN_LEDAKEMLT52_LEAKTIME_niederreiter_decrypt(decoded_error_vector,
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(const privateKeyNiederreiter_t *)sk, syndrome);
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pack_error(decoded_error_bytes, decoded_error_vector);
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HASH_FUNCTION(hashedErrorVector, decoded_error_bytes, N0 * NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B);
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memcpy(hashedAndTruncatedErrorVector, hashedErrorVector, TRNG_BYTE_LENGTH);
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for (size_t i = 0; i < TRNG_BYTE_LENGTH; ++i) {
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decoded_seed[i] = ct[(NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B) + i] ^
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hashedAndTruncatedErrorVector[i];
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}
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HASH_FUNCTION(hashed_decoded_seed, decoded_seed, TRNG_BYTE_LENGTH);
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memcpy(hashedAndTruncated_decoded_seed, hashed_decoded_seed, TRNG_BYTE_LENGTH);
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memset(&hashedAndTruncatedSeed_expander, 0x00, sizeof(AES_XOF_struct));
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PQCLEAN_LEDAKEMLT52_LEAKTIME_seedexpander_from_trng(&hashedAndTruncatedSeed_expander,
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hashed_decoded_seed);
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PQCLEAN_LEDAKEMLT52_LEAKTIME_rand_error_pos(reconstructed_errorPos, &hashedAndTruncatedSeed_expander);
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PQCLEAN_LEDAKEMLT52_LEAKTIME_expand_error(reconstructed_error_vector, reconstructed_errorPos);
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equal = PQCLEAN_LEDAKEMLT52_LEAKTIME_gf2x_verify(decoded_error_vector,
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reconstructed_error_vector, N0 * NUM_DIGITS_GF2X_ELEMENT);
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// equal == 0, if the reconstructed error vector match !!!
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decrypt_ok = (decode_ok == 1 && equal == 0);
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memcpy(ss_input, decoded_seed, TRNG_BYTE_LENGTH);
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memcpy(ss_input + sizeof(decoded_seed), tail, TRNG_BYTE_LENGTH);
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// Overwrite on failure
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PQCLEAN_LEDAKEMLT52_LEAKTIME_cmov(ss_input + sizeof(decoded_seed),
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((const privateKeyNiederreiter_t *) sk)->decryption_failure_secret,
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TRNG_BYTE_LENGTH,
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!decrypt_ok);
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HASH_FUNCTION(ss, ss_input, 2 * TRNG_BYTE_LENGTH);
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return 0;
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}
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