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pqcrypto/crypto_kem/hqc-rmrs-192/avx2/kem.c
2021-03-24 21:02:47 +00:00

139 lines
4.3 KiB
C

#include "api.h"
#include "fips202.h"
#include "hqc.h"
#include "nistseedexpander.h"
#include "parameters.h"
#include "parsing.h"
#include "randombytes.h"
#include "sha2.h"
#include "vector.h"
#include <stdint.h>
#include <string.h>
/**
* @file kem.c
* @brief Implementation of api.h
*/
/**
* @brief Keygen of the HQC_KEM IND_CAA2 scheme
*
* The public key is composed of the syndrome <b>s</b> as well as the seed used to generate the vector <b>h</b>.
*
* The secret key is composed of the seed used to generate vectors <b>x</b> and <b>y</b>.
* As a technicality, the public key is appended to the secret key in order to respect NIST API.
*
* @param[out] pk String containing the public key
* @param[out] sk String containing the secret key
* @returns 0 if keygen is successful
*/
int PQCLEAN_HQCRMRS192_AVX2_crypto_kem_keypair(unsigned char *pk, unsigned char *sk) {
PQCLEAN_HQCRMRS192_AVX2_hqc_pke_keygen(pk, sk);
return 0;
}
/**
* @brief Encapsulation of the HQC_KEM IND_CAA2 scheme
*
* @param[out] ct String containing the ciphertext
* @param[out] ss String containing the shared secret
* @param[in] pk String containing the public key
* @returns 0 if encapsulation is successful
*/
int PQCLEAN_HQCRMRS192_AVX2_crypto_kem_enc(unsigned char *ct, unsigned char *ss, const unsigned char *pk) {
uint8_t theta[SHA512_BYTES] = {0};
uint64_t m[VEC_K_SIZE_64] = {0};
uint64_t u[VEC_N_256_SIZE_64] = {0};
uint64_t v[VEC_N1N2_256_SIZE_64] = {0};
unsigned char d[SHA512_BYTES] = {0};
unsigned char mc[VEC_K_SIZE_BYTES + VEC_N_SIZE_BYTES + VEC_N1N2_SIZE_BYTES] = {0};
// Computing m
PQCLEAN_HQCRMRS192_AVX2_vect_set_random_from_randombytes(m);
// Computing theta
sha3_512(theta, (uint8_t *) m, VEC_K_SIZE_BYTES);
// Encrypting m
PQCLEAN_HQCRMRS192_AVX2_hqc_pke_encrypt(u, v, m, theta, pk);
// Computing d
sha512(d, (unsigned char *) m, VEC_K_SIZE_BYTES);
// Computing shared secret
memcpy(mc, m, VEC_K_SIZE_BYTES);
memcpy(mc + VEC_K_SIZE_BYTES, u, VEC_N_SIZE_BYTES);
memcpy(mc + VEC_K_SIZE_BYTES + VEC_N_SIZE_BYTES, v, VEC_N1N2_SIZE_BYTES);
sha512(ss, mc, VEC_K_SIZE_BYTES + VEC_N_SIZE_BYTES + VEC_N1N2_SIZE_BYTES);
// Computing ciphertext
PQCLEAN_HQCRMRS192_AVX2_hqc_ciphertext_to_string(ct, u, v, d);
return 0;
}
/**
* @brief Decapsulation of the HQC_KEM IND_CAA2 scheme
*
* @param[out] ss String containing the shared secret
* @param[in] ct String containing the cipĥertext
* @param[in] sk String containing the secret key
* @returns 0 if decapsulation is successful, -1 otherwise
*/
int PQCLEAN_HQCRMRS192_AVX2_crypto_kem_dec(unsigned char *ss, const unsigned char *ct, const unsigned char *sk) {
int8_t result = -1;
uint64_t u[VEC_N_256_SIZE_64] = {0};
uint64_t v[VEC_N1N2_256_SIZE_64] = {0};
unsigned char d[SHA512_BYTES] = {0};
unsigned char pk[PUBLIC_KEY_BYTES] = {0};
uint64_t m[VEC_K_SIZE_64] = {0};
uint8_t theta[SHA512_BYTES] = {0};
uint64_t u2[VEC_N_256_SIZE_64] = {0};
uint64_t v2[VEC_N1N2_256_SIZE_64] = {0};
unsigned char d2[SHA512_BYTES] = {0};
unsigned char mc[VEC_K_SIZE_BYTES + VEC_N_SIZE_BYTES + VEC_N1N2_SIZE_BYTES] = {0};
// Retrieving u, v and d from ciphertext
PQCLEAN_HQCRMRS192_AVX2_hqc_ciphertext_from_string(u, v, d, ct);
// Retrieving pk from sk
memcpy(pk, sk + SEED_BYTES, PUBLIC_KEY_BYTES);
// Decryting
PQCLEAN_HQCRMRS192_AVX2_hqc_pke_decrypt(m, u, v, sk);
// Computing theta
sha3_512(theta, (uint8_t *) m, VEC_K_SIZE_BYTES);
// Encrypting m'
PQCLEAN_HQCRMRS192_AVX2_hqc_pke_encrypt(u2, v2, m, theta, pk);
// Computing d'
sha512(d2, (unsigned char *) m, VEC_K_SIZE_BYTES);
// Computing shared secret
memcpy(mc, m, VEC_K_SIZE_BYTES);
memcpy(mc + VEC_K_SIZE_BYTES, u, VEC_N_SIZE_BYTES);
memcpy(mc + VEC_K_SIZE_BYTES + VEC_N_SIZE_BYTES, v, VEC_N1N2_SIZE_BYTES);
sha512(ss, mc, VEC_K_SIZE_BYTES + VEC_N_SIZE_BYTES + VEC_N1N2_SIZE_BYTES);
// Abort if c != c' or d != d'
result = (PQCLEAN_HQCRMRS192_AVX2_vect_compare(u, u2, VEC_N_SIZE_BYTES) == 0 && PQCLEAN_HQCRMRS192_AVX2_vect_compare(v, v2, VEC_N1N2_SIZE_BYTES) == 0 && PQCLEAN_HQCRMRS192_AVX2_vect_compare((uint64_t *)d, (uint64_t *)d2, SHA512_BYTES) == 0);
for (size_t i = 0 ; i < SHARED_SECRET_BYTES ; i++) {
ss[i] = result * ss[i];
}
result--;
return result;
}