lwe_fs.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_LWE_FS_H
#define CIFER_LWE_FS_H
 
#include <math.h>
#include <gmp.h>
 
#include "cifer/data/vec.h"
#include "cifer/data/mat.h"
#include "cifer/internal/errors.h"
 
typedef struct cfe_lwe_fs {
    size_t l; // Length of data vectors for inner product
 
    size_t n; // Main security parameters of the scheme
    size_t m; // Number of samples
 
    // Message space size
    mpz_t bound_x;
    // Inner product vector space size
    mpz_t bound_y;
    // Modulus for the resulting inner product.
    // K depends on the parameters l, P and V and is computed by the scheme.
    mpz_t K;
    // Modulus for ciphertext and keys.
    // Must be significantly larger than K.
    mpz_t q;
    // standard deviation for the noise terms in the encryption process
    mpf_t sigma_q;
    mpz_t k_sigma_q;
    // standard deviation for first half of the matrix for sampling private key
    mpf_t sigma1;
    mpz_t k_sigma1;
    // standard deviation for second half of the matrix for sampling private key
    mpf_t sigma2;
    mpz_t k_sigma2;
 
    // Matrix A of dimensions m*n is a public parameter
    // of the scheme
    cfe_mat A;
} cfe_lwe_fs;
 
cfe_error cfe_lwe_fs_init(cfe_lwe_fs *s, size_t l, size_t n, mpz_t bound_x, mpz_t bound_y);
 
void cfe_lwe_fs_sec_key_init(cfe_mat *SK, cfe_lwe_fs *s);
 
void cfe_lwe_fs_generate_sec_key(cfe_mat *SK, cfe_lwe_fs *s);
 
void cfe_lwe_fs_pub_key_init(cfe_mat *PK, cfe_lwe_fs *s);
 
cfe_error cfe_lwe_fs_generate_pub_key(cfe_mat *PK, cfe_lwe_fs *s, cfe_mat *SK);
 
void cfe_lwe_fs_fe_key_init(cfe_vec *z_y, cfe_lwe_fs *s);
 
cfe_error cfe_lwe_fs_derive_fe_key(cfe_vec *z_y, cfe_lwe_fs *s, cfe_vec *y, cfe_mat *SK);
 
void cfe_lwe_fs_ciphertext_init(cfe_vec *ct, cfe_lwe_fs *s);
 
cfe_error cfe_lwe_fs_encrypt(cfe_vec *ct, cfe_lwe_fs *s, cfe_vec *x, cfe_mat *PK);
 
cfe_error cfe_lwe_fs_decrypt(mpz_t res, cfe_lwe_fs *s, cfe_vec *ct, cfe_vec *z_y, cfe_vec *y);
 
void cfe_lwe_fs_free(cfe_lwe_fs *s);
 
#endif