116 lines
2.7 KiB
C
116 lines
2.7 KiB
C
/*
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* Copyright (C) 2014 FH Bielefeld
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*
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* This file is part of a FH Bielefeld project.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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/**
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* @file encrypt.c
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* This file handles the NTRU encryption
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* algorithm.
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* @brief NTRU encryption
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*/
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#include "ascii_poly.h"
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#include "encrypt.h"
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#include "mem.h"
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#include "ntru_string.h"
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#include <string.h>
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#include <fmpz_poly.h>
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#include <fmpz.h>
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/*------------------------------------------------------------------------*/
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void
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ntru_encrypt_poly(
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fmpz_poly_t msg_bin,
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fmpz_poly_t pub_key,
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fmpz_poly_t rnd,
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fmpz_poly_t out,
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ntru_context *ctx)
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{
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/* allow aliasing */
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fmpz_poly_t tmp_poly_msg;
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fmpz_poly_init(tmp_poly_msg);
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fmpz_poly_set(tmp_poly_msg, msg_bin);
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fmpz_poly_zero(out);
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poly_starmultiply(pub_key, rnd, out, ctx, ctx->q);
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fmpz_poly_add(out, out, tmp_poly_msg);
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fmpz_poly_mod(out, ctx->q);
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/*
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* using the flint functions
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* fmpz_poly_add(out, out, tmp_poly_msg);
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* fmpz_poly_mod_unsigned(out, ctx->q);
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* here instead caused very rare glitches in some cases,
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* TODO: investigate
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*/
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for (uint32_t i = 0; i < ctx->N; i++) {
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printf("go ");
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fmpz_t e_coeff_i;
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fmpz *m_coeff_i = fmpz_poly_get_coeff_ptr(tmp_poly_msg, i);
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fmpz_init(e_coeff_i);
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fmpz_add_n(e_coeff_i, e_coeff_i, m_coeff_i);
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fmpz_mod_ui(e_coeff_i, e_coeff_i, ctx->q);
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fmpz_poly_set_coeff_fmpz_n(out, i, e_coeff_i);
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}
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fmpz_poly_clear(tmp_poly_msg);
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}
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/*------------------------------------------------------------------------*/
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string *
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ntru_encrypt_string(
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char *msg,
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fmpz_poly_t pub_key,
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fmpz_poly_t rnd,
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ntru_context *ctx)
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{
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uint32_t i = 0;
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string *enc_msg;
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fmpz_poly_t **poly_array;
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poly_array = ascii_to_bin_poly_arr(msg, ctx);
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while (*poly_array[i]) {
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poly_draw(*poly_array[i]);
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ntru_encrypt_poly(*poly_array[i],
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pub_key,
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rnd,
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*poly_array[i],
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ctx);
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i++;
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}
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enc_msg = poly_arr_to_base64(poly_array, ctx);
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poly_delete_array(poly_array);
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return enc_msg;
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}
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/*------------------------------------------------------------------------*/
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