mirror of
https://github.com/henrydcase/pqc.git
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139 lines
5.0 KiB
C
139 lines
5.0 KiB
C
#include "code.h"
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#include "gf2x.h"
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#include "hqc.h"
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#include "nistseedexpander.h"
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#include "parameters.h"
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#include "parsing.h"
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#include "randombytes.h"
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#include "vector.h"
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#include <stdint.h>
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/**
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* @file hqc.c
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* @brief Implementation of hqc.h
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*/
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/**
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* @brief Keygen of the HQC_PKE IND_CPA scheme
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*
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* The public key is composed of the syndrome <b>s</b> as well as the <b>seed</b> used to generate the vector <b>h</b>.
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*
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* The secret key is composed of the <b>seed</b> used to generate vectors <b>x</b> and <b>y</b>.
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* As a technicality, the public key is appended to the secret key in order to respect NIST API.
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*
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* @param[out] pk String containing the public key
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* @param[out] sk String containing the secret key
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*/
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void PQCLEAN_HQCRMRS128_AVX2_hqc_pke_keygen(unsigned char *pk, unsigned char *sk) {
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AES_XOF_struct sk_seedexpander;
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AES_XOF_struct pk_seedexpander;
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uint8_t sk_seed[SEED_BYTES] = {0};
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uint8_t pk_seed[SEED_BYTES] = {0};
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uint64_t x[VEC_N_256_SIZE_64] = {0};
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uint64_t y[VEC_N_256_SIZE_64] = {0};
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uint64_t h[VEC_N_256_SIZE_64] = {0};
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uint64_t s[VEC_N_256_SIZE_64] = {0};
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// Create seed_expanders for public key and secret key
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randombytes(sk_seed, SEED_BYTES);
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seedexpander_init(&sk_seedexpander, sk_seed, sk_seed + 32, SEEDEXPANDER_MAX_LENGTH);
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randombytes(pk_seed, SEED_BYTES);
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seedexpander_init(&pk_seedexpander, pk_seed, pk_seed + 32, SEEDEXPANDER_MAX_LENGTH);
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// Compute secret key
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PQCLEAN_HQCRMRS128_AVX2_vect_set_random_fixed_weight(&sk_seedexpander, x, PARAM_OMEGA);
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PQCLEAN_HQCRMRS128_AVX2_vect_set_random_fixed_weight(&sk_seedexpander, y, PARAM_OMEGA);
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// Compute public key
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PQCLEAN_HQCRMRS128_AVX2_vect_set_random(&pk_seedexpander, h);
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PQCLEAN_HQCRMRS128_AVX2_vect_mul(s, y, h);
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PQCLEAN_HQCRMRS128_AVX2_vect_add(s, x, s, VEC_N_256_SIZE_64);
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// Parse keys to string
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PQCLEAN_HQCRMRS128_AVX2_hqc_public_key_to_string(pk, pk_seed, s);
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PQCLEAN_HQCRMRS128_AVX2_hqc_secret_key_to_string(sk, sk_seed, pk);
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}
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/**
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* @brief Encryption of the HQC_PKE IND_CPA scheme
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*
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* The cihertext is composed of vectors <b>u</b> and <b>v</b>.
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*
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* @param[out] u Vector u (first part of the ciphertext)
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* @param[out] v Vector v (second part of the ciphertext)
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* @param[in] m Vector representing the message to encrypt
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* @param[in] theta Seed used to derive randomness required for encryption
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* @param[in] pk String containing the public key
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*/
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void PQCLEAN_HQCRMRS128_AVX2_hqc_pke_encrypt(uint64_t *u, uint64_t *v, uint64_t *m, unsigned char *theta, const unsigned char *pk) {
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AES_XOF_struct seedexpander;
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uint64_t h[VEC_N_256_SIZE_64] = {0};
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uint64_t s[VEC_N_256_SIZE_64] = {0};
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uint64_t r1[VEC_N_256_SIZE_64] = {0};
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uint64_t r2[VEC_N_256_SIZE_64] = {0};
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uint64_t e[VEC_N_256_SIZE_64] = {0};
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uint64_t tmp1[VEC_N_256_SIZE_64] = {0};
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uint64_t tmp2[VEC_N_256_SIZE_64] = {0};
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// Create seed_expander from theta
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seedexpander_init(&seedexpander, theta, theta + 32, SEEDEXPANDER_MAX_LENGTH);
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// Retrieve h and s from public key
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PQCLEAN_HQCRMRS128_AVX2_hqc_public_key_from_string(h, s, pk);
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// Generate r1, r2 and e
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PQCLEAN_HQCRMRS128_AVX2_vect_set_random_fixed_weight(&seedexpander, r1, PARAM_OMEGA_R);
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PQCLEAN_HQCRMRS128_AVX2_vect_set_random_fixed_weight(&seedexpander, r2, PARAM_OMEGA_R);
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PQCLEAN_HQCRMRS128_AVX2_vect_set_random_fixed_weight(&seedexpander, e, PARAM_OMEGA_E);
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// Compute u = r1 + r2.h
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PQCLEAN_HQCRMRS128_AVX2_vect_mul(u, r2, h);
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PQCLEAN_HQCRMRS128_AVX2_vect_add(u, r1, u, VEC_N_256_SIZE_64);
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// Compute v = m.G by encoding the message
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PQCLEAN_HQCRMRS128_AVX2_code_encode(v, m);
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PQCLEAN_HQCRMRS128_AVX2_vect_resize(tmp1, PARAM_N, v, PARAM_N1N2);
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// Compute v = m.G + s.r2 + e
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PQCLEAN_HQCRMRS128_AVX2_vect_mul(tmp2, r2, s);
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PQCLEAN_HQCRMRS128_AVX2_vect_add(tmp2, e, tmp2, VEC_N_256_SIZE_64);
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PQCLEAN_HQCRMRS128_AVX2_vect_add(tmp2, tmp1, tmp2, VEC_N_256_SIZE_64);
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PQCLEAN_HQCRMRS128_AVX2_vect_resize(v, PARAM_N1N2, tmp2, PARAM_N);
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}
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/**
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* @brief Decryption of the HQC_PKE IND_CPA scheme
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*
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* @param[out] m Vector representing the decrypted message
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* @param[in] u Vector u (first part of the ciphertext)
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* @param[in] v Vector v (second part of the ciphertext)
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* @param[in] sk String containing the secret key
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*/
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void PQCLEAN_HQCRMRS128_AVX2_hqc_pke_decrypt(uint64_t *m, const uint64_t *u, const uint64_t *v, const unsigned char *sk) {
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uint64_t x[VEC_N_256_SIZE_64] = {0};
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uint64_t y[VEC_N_256_SIZE_64] = {0};
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uint8_t pk[PUBLIC_KEY_BYTES] = {0};
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uint64_t tmp1[VEC_N_256_SIZE_64] = {0};
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uint64_t tmp2[VEC_N_256_SIZE_64] = {0};
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// Retrieve x, y, pk from secret key
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PQCLEAN_HQCRMRS128_AVX2_hqc_secret_key_from_string(x, y, pk, sk);
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// Compute v - u.y
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PQCLEAN_HQCRMRS128_AVX2_vect_resize(tmp1, PARAM_N, v, PARAM_N1N2);
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PQCLEAN_HQCRMRS128_AVX2_vect_mul(tmp2, y, u);
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PQCLEAN_HQCRMRS128_AVX2_vect_add(tmp2, tmp1, tmp2, VEC_N_256_SIZE_64);
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// Compute m by decoding v - u.y
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PQCLEAN_HQCRMRS128_AVX2_code_decode(m, tmp2);
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}
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