ntru_poly_ascii.c

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/*
 * Copyright (C) 2014 FH Bielefeld
 *
 * This file is part of a FH Bielefeld project.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA  02110-1301  USA
 */

#include "ntru_poly_ascii.h"
#include "ntru_common.h"
#include "ntru_mem.h"
#include "ntru_params.h"
#include "ntru_poly.h"
#include "ntru_string.h"

#include <glib.h>

#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include <fmpz_poly.h>
#include <fmpz.h>


static string *
get_bin_arr_to_ascii(const char *binary_rep);


/*------------------------------------------------------------------------*/

static string *
get_bin_arr_to_ascii(const char *binary_rep)
{
    size_t int_arr_size = 0;
    uint8_t *int_arr = NULL;
    uint32_t i = 0;
    char *int_string = NULL;
    string *result = ntru_malloc(sizeof(*result));

    if (!binary_rep || !*binary_rep)
        return NULL;

    int_arr_size = strlen(binary_rep) / ASCII_BITS + 1;
    int_arr = ntru_malloc(sizeof(*int_arr) * int_arr_size);

    while (*binary_rep) {
        int_arr[i] = 0;

        /* convert one binary integer to real integer */
        for (uint32_t j = 0; j < ASCII_BITS && *binary_rep; j++) {
            if (*binary_rep == '1')
                int_arr[i] = int_arr[i] * 2 + 1;
            else if (*binary_rep == '0')
                int_arr[i] *= 2;
            binary_rep++;
        }

        i++; /* amount of real integers */
    }

    int_string = ntru_malloc(CHAR_SIZE * (i + 1));

    for (uint32_t j = 0; j < i; j++)
        int_string[j] = (char) int_arr[j];

    result->ptr = int_string;
    result->len = i;

    free(int_arr);

    return result;
}

/*------------------------------------------------------------------------*/

string *
bin_poly_to_ascii(const fmpz_poly_t poly,
        const ntru_params *params)
{
    string *result_string = ntru_malloc(sizeof(*result_string));
    char *binary_rep = ntru_malloc(CHAR_SIZE * (params->N));
    uint32_t i = 0;

    for (i = 0; i < params->N; i++) {
        fmpz *coeff = fmpz_poly_get_coeff_ptr(poly, i);

        if (coeff) {
            if (!fmpz_cmp_si(coeff, 1))
                binary_rep[i] = '1';
            else if (!fmpz_cmp_si(coeff, -1))
                binary_rep[i] = '0';
        } else {
            break;
        }
    }

    result_string->ptr = binary_rep;
    result_string->len = i;

    return result_string;
}

/*------------------------------------------------------------------------*/

string *
bin_poly_arr_to_ascii(const fmpz_poly_t **bin_poly_arr,
        const uint32_t poly_c,
        const ntru_params *params)
{
    char *binary_rep = NULL;
    size_t string_len = 0;
    string *ascii_string = NULL;

    /*
     * parse the polynomial coefficients into a string
     */
    binary_rep = ntru_malloc(CHAR_SIZE * (params->N * poly_c + 1));
    for (uint32_t i = 0; i < poly_c; i++) {
        string *single_poly_string = NULL;

        single_poly_string = bin_poly_to_ascii(*bin_poly_arr[i], params);

        memcpy(binary_rep + string_len,
                single_poly_string->ptr,
                single_poly_string->len);

        string_len += single_poly_string->len;

        string_delete(single_poly_string);
    }
    binary_rep[string_len] = '\0';

    ascii_string = get_bin_arr_to_ascii(binary_rep);

    free(binary_rep);

    return ascii_string;
}

/*------------------------------------------------------------------------*/

string *
poly_to_ascii(const fmpz_poly_t poly,
        const ntru_params *params)
{
    string *result_string = ntru_malloc(sizeof(*result_string));
    char *string_rep = ntru_malloc(CHAR_SIZE * (params->N));

    for (uint32_t j = 0; j < params->N; j++) {
        uint8_t coeff = fmpz_poly_get_coeff_ui(poly, j);
        if (coeff == params->q)
            string_rep[j] = '\0';
        else
            string_rep[j] = (char)coeff;
    }

    result_string->ptr = string_rep;
    result_string->len = params->N;

    return result_string;
}

/*------------------------------------------------------------------------*/

string *
poly_arr_to_ascii(const fmpz_poly_t **poly_array,
        const uint32_t poly_c,
        const ntru_params *params)
{
    char *string_rep = NULL;
    size_t string_len = 0;
    string *result_string = ntru_malloc(sizeof(*result_string));

    /*
     * parse the polynomial coefficients into a string
     */
    string_rep = ntru_malloc(CHAR_SIZE * (params->N * poly_c + 1));
    for (uint32_t i = 0; i < poly_c; i++) {
        string *poly_str;

        poly_str = poly_to_ascii(*poly_array[i], params);

        memcpy(string_rep + string_len,
                poly_str->ptr,
                poly_str->len);
        string_len += poly_str->len;

        string_delete(poly_str);
    }

    result_string->ptr = string_rep;
    result_string->len = string_len;

    return result_string;
}

/*------------------------------------------------------------------------*/

string *
poly_to_base64(const fmpz_poly_t poly,
        const ntru_params *params)
{
    string *result_string = ntru_malloc(sizeof(*result_string));
    string *string_rep = NULL;
    gchar *base64_string = NULL,
          *tmp = NULL;

    string_rep = poly_to_ascii(poly, params);

    tmp = g_base64_encode((const guchar *)string_rep->ptr,
            string_rep->len);
    base64_string = g_base64_encode((const guchar *)tmp,
            strlen(tmp));

    result_string->ptr = base64_string;
    result_string->len = strlen(base64_string);

    string_delete(string_rep);
    free(tmp);

    return result_string;
}

/*------------------------------------------------------------------------*/

string *
poly_arr_to_base64(const fmpz_poly_t **poly_array,
        const uint32_t poly_c,
        const ntru_params *params)
{
    string *string_rep;
    string *result_string = ntru_malloc(sizeof(*result_string));

    gchar *base64_string = NULL,
          *tmp = NULL;

    string_rep = poly_arr_to_ascii(poly_array, poly_c, params);

    tmp = g_base64_encode((const guchar *)string_rep->ptr, string_rep->len);
    base64_string = g_base64_encode((const guchar *)tmp,
            strlen(tmp));

    result_string->ptr = base64_string;
    result_string->len = strlen(base64_string);

    string_delete(string_rep);
    free(tmp);

    return result_string;
}

/*------------------------------------------------------------------------*/