105 lines
2.8 KiB
C++
105 lines
2.8 KiB
C++
|
/*
|
||
|
|
* 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.
|
||
|
|
*
|
||
|
|
* Copyright 2015 Danny Robson <danny@nerdcruft.net>
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "xxtea.hpp"
|
||
|
|
|
||
|
|
#include <cstring>
|
||
|
|
|
||
|
|
// test vectors: http://www.cix.co.uk/~klockstone/teavect.htm
|
||
|
|
|
||
|
|
using util::crypto::XXTEA;
|
||
|
|
|
||
|
|
|
||
|
|
//-----------------------------------------------------------------------------
|
||
|
|
static const uint32_t MAGIC = 0x9E3779B9;
|
||
|
|
static const unsigned ITERATIONS = 32; // each iteration performs two feistel rounds
|
||
|
|
|
||
|
|
|
||
|
|
//-----------------------------------------------------------------------------
|
||
|
|
static constexpr uint32_t mix (uint32_t Z,
|
||
|
|
uint32_t Y,
|
||
|
|
uint32_t S,
|
||
|
|
size_t E,
|
||
|
|
size_t P,
|
||
|
|
const uint32_t *restrict K)
|
||
|
|
{
|
||
|
|
return ((Z >> 5 ^ Y << 2) + (Y >> 3 ^ Z << 4)) ^ ((S ^ Y) + (K[(P & 3) ^ E] ^ Z));
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
//-----------------------------------------------------------------------------
|
||
|
|
XXTEA::XXTEA (key_t _key):
|
||
|
|
m_key (_key)
|
||
|
|
{ ; }
|
||
|
|
|
||
|
|
|
||
|
|
//-----------------------------------------------------------------------------
|
||
|
|
void
|
||
|
|
XXTEA::encrypt (uint32_t *restrict data, size_t count)
|
||
|
|
{
|
||
|
|
if (count < 2)
|
||
|
|
throw std::invalid_argument ("minimum blocksize is 64 bits");
|
||
|
|
|
||
|
|
uint32_t sum = 0;
|
||
|
|
uint32_t z = data[count - 1];
|
||
|
|
uint32_t y, e, p;
|
||
|
|
|
||
|
|
unsigned rounds = 6 + 52 / count;
|
||
|
|
|
||
|
|
do {
|
||
|
|
sum += MAGIC;
|
||
|
|
e = (sum >> 2) & 3;
|
||
|
|
|
||
|
|
for (p = 0; p < count - 1; p++) {
|
||
|
|
y = data[p + 1];
|
||
|
|
z = data[p] += mix (z, y, sum, e, p, m_key.data ());
|
||
|
|
}
|
||
|
|
|
||
|
|
y = data[0];
|
||
|
|
z = data[count - 1] += mix (z, y, sum, e, p, m_key.data ());
|
||
|
|
} while (--rounds);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
//-----------------------------------------------------------------------------
|
||
|
|
void
|
||
|
|
XXTEA::decrypt (uint32_t *restrict data, size_t count)
|
||
|
|
{
|
||
|
|
if (count < 2)
|
||
|
|
throw std::invalid_argument ("minimum blocksize is 64 bits");
|
||
|
|
|
||
|
|
uint32_t y, z, sum;
|
||
|
|
unsigned p, rounds, e;
|
||
|
|
|
||
|
|
rounds = 6 + 52 / count;
|
||
|
|
sum = rounds * MAGIC;
|
||
|
|
y = data[0];
|
||
|
|
|
||
|
|
do {
|
||
|
|
e = (sum >> 2) & 3;
|
||
|
|
|
||
|
|
for (p = count - 1; p > 0; p--) {
|
||
|
|
z = data[p - 1];
|
||
|
|
y = data[p ] -= mix (z, y, sum, e, p, m_key.data ());
|
||
|
|
}
|
||
|
|
|
||
|
|
z = data[count - 1];
|
||
|
|
y = data[ 0] -= mix (z, y, sum, e, p, m_key.data ());
|
||
|
|
|
||
|
|
sum -= MAGIC;
|
||
|
|
} while (--rounds);
|
||
|
|
}
|