ring_lwe.h

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/*
 * Copyright (c) 2018 XLAB d.o.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#ifndef CIFER_RING_LWE_H
#define CIFER_RING_LWE_H
 
#include <math.h>
#include <gmp.h>
 
#include "cifer/data/vec.h"
#include "cifer/data/mat.h"
#include "cifer/internal/errors.h"
#include "cifer/sample/normal_cumulative.h"
 
typedef struct cfe_ring_lwe {
    size_t l;    // Length of data vectors for inner product
 
    size_t n;    // main security parameters of the scheme
 
    mpz_t bound; // Data vector coordinates should be strictly smaller than bound
 
    mpz_t p;  // Modulus for message space
    mpz_t q;  // Modulus for ciphertext and keys
 
    // vector a of dimension n representing the random polynomial for the scheme
    cfe_vec a;
 
    // sampler
    cfe_normal_cumulative sampler;
} cfe_ring_lwe;
 
// TODO: this scheme needs automatic parameters generation and the input should
// depend only on n, l, bound_x, bound_y (i.e. also bound x and bound_y should be separated),
// this needs some theoretical effort.
 
cfe_error cfe_ring_lwe_init(cfe_ring_lwe *s, size_t l, size_t n, mpz_t bound, mpz_t p, mpz_t q, mpf_t sigma);
 
void cfe_ring_lwe_sec_key_init(cfe_mat *SK, cfe_ring_lwe *s);
 
void cfe_ring_lwe_generate_sec_key(cfe_mat *SK, cfe_ring_lwe *s);
 
void cfe_ring_lwe_pub_key_init(cfe_mat *PK, cfe_ring_lwe *s);
 
cfe_error cfe_ring_lwe_generate_pub_key(cfe_mat *PK, cfe_ring_lwe *s, cfe_mat *SK);
 
void cfe_ring_lwe_fe_key_init(cfe_vec *sk_y, cfe_ring_lwe *s);
 
cfe_error cfe_ring_lwe_derive_fe_key(cfe_vec *sk_y, cfe_ring_lwe *s, cfe_mat *SK, cfe_vec *y);
 
void cfe_ring_lwe_ciphertext_init(cfe_mat *CT, cfe_ring_lwe *s);
 
cfe_error cfe_ring_lwe_encrypt(cfe_mat *CT, cfe_ring_lwe *s, cfe_mat *x, cfe_mat *PK);
 
void cfe_ring_lwe_decrypted_init(cfe_vec *res, cfe_ring_lwe *s);
 
cfe_error cfe_ring_lwe_decrypt(cfe_vec *res, cfe_ring_lwe *s, cfe_mat *ct, cfe_vec *sk_y, cfe_vec *y);
 
void cfe_ring_lwe_free(cfe_ring_lwe *s);
 
#endif