crypto.cpp

/*
 *  Copyright (C) 2014-2022 Savoir-faire Linux Inc.
 *  Author : Adrien Béraud <adrien.beraud@savoirfairelinux.com>
 *           Vsevolod Ivanov <vsevolod.ivanov@savoirfairelinux.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program. If not, see <https://www.gnu.org/licenses/>.
 */

#include "crypto.h"
#include "rng.h"

extern "C" {
#include <gnutls/gnutls.h>
#include <gnutls/abstract.h>
#include <gnutls/x509.h>
#include <nettle/gcm.h>
#include <nettle/aes.h>
#include <gnutls/crypto.h>

#include <argon2.h>
}

#include <random>
#include <sstream>
#include <fstream>
#include <stdexcept>
#include <cassert>

#ifdef _WIN32
static std::uniform_int_distribution<int> rand_byte{ 0, std::numeric_limits<uint8_t>::max() };
#else
static std::uniform_int_distribution<uint8_t> rand_byte;
#endif

#define DHT_AES_LEGACY_DECRYPT 1

namespace dht {
namespace crypto {

static constexpr std::array<size_t, 3> AES_LENGTHS {{128/8, 192/8, 256/8}};
static constexpr size_t PASSWORD_SALT_LENGTH {16};

constexpr gnutls_digest_algorithm_t gnutlsHashAlgo(size_t min_res) {
    return (min_res > 256/8) ? GNUTLS_DIG_SHA512 : (
           (min_res > 160/8) ? GNUTLS_DIG_SHA256 : (
                               GNUTLS_DIG_SHA1));
}

constexpr size_t gnutlsHashSize(gnutls_digest_algorithm_t algo) {
    return (algo == GNUTLS_DIG_SHA512) ? 512/8 : (
           (algo == GNUTLS_DIG_SHA256) ? 256/8 : (
           (algo == GNUTLS_DIG_SHA1)   ? 160/8 : 0 ));
}

size_t aesKeySize(size_t max)
{
    size_t aes_key_len = 0;
    for (size_t s : AES_LENGTHS) {
        if (s <= max) aes_key_len = s;