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/*
* Copyright (c) 2013-2024 Hutool Team and hutool.cn
*
* 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.
*/
package org.dromara.hutool.crypto.symmetric;
import org.dromara.hutool.core.io.IoUtil;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Serializable;
/**
* XXTEA（Corrected Block Tiny Encryption Algorithm）算法实现
* 来自：https://github.com/xxtea/xxtea-java
*
* @author Ma Bingyao
*/
public class XXTEA implements SymmetricEncryptor, SymmetricDecryptor, Serializable {
private static final long serialVersionUID = 1L;
private static final int DELTA = 0x9E3779B9;
private final byte[] key;
/**
* 构造
*
* @param key 密钥，16位
*/
public XXTEA(final byte[] key) {
this.key = key;
}
@Override
public byte[] encrypt(final byte[] data) {
if (data.length == 0) {
return data;
}
return toByteArray(encrypt(
toIntArray(data, true),
toIntArray(fixKey(key), false)), false);
}
@Override
public void encrypt(final InputStream data, final OutputStream out, final boolean isClose) {
IoUtil.write(out, isClose, encrypt(IoUtil.readBytes(data)));
}
@Override
public byte[] decrypt(final byte[] data) {
if (data.length == 0) {
return data;
}
return toByteArray(decrypt(
toIntArray(data, false),
toIntArray(fixKey(key), false)), true);
}
@Override
public void decrypt(final InputStream data, final OutputStream out, final boolean isClose) {
IoUtil.write(out, isClose, decrypt(IoUtil.readBytes(data)));
}
//region Private Method
private static int[] encrypt(final int[] v, final int[] k) {
final int n = v.length - 1;
if (n < 1) {
return v;
}
int p, q = 6 + 52 / (n + 1);
int z = v[n], y, sum = 0, e;
while (q-- > 0) {
sum = sum + DELTA;
e = sum >>> 2 & 3;
for (p = 0; p < n; p++) {
y = v[p + 1];
z = v[p] += mx(sum, y, z, p, e, k);
}
y = v[0];
z = v[n] += mx(sum, y, z, p, e, k);
}
return v;
}
private static int[] decrypt(final int[] v, final int[] k) {
final int n = v.length - 1;
if (n < 1) {
return v;
}
int p;
final int q = 6 + 52 / (n + 1);
int z, y = v[0], sum = q * DELTA, e;
while (sum != 0) {
e = sum >>> 2 & 3;
for (p = n; p > 0; p--) {
z = v[p - 1];
y = v[p] -= mx(sum, y, z, p, e, k);
}
z = v[n];
y = v[0] -= mx(sum, y, z, p, e, k);
sum = sum - DELTA;
}
return v;
}
private static int mx(final int sum, final int y, final int z, final int p, final int e, final int[] k) {
return (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
}
private static byte[] fixKey(final byte[] key) {
if (key.length == 16) {
return key;
}
final byte[] fixedkey = new byte[16];
System.arraycopy(key, 0, fixedkey, 0, Math.min(key.length, 16));
return fixedkey;
}
private static int[] toIntArray(final byte[] data, final boolean includeLength) {
int n = (((data.length & 3) == 0)
? (data.length >>> 2)
: ((data.length >>> 2) + 1));
final int[] result;
if (includeLength) {
result = new int[n + 1];
result[n] = data.length;
} else {
result = new int[n];
}
n = data.length;
for (int i = 0; i < n; ++i) {
result[i >>> 2] |= (0x000000ff & data[i]) << ((i & 3) << 3);
}
return result;
}
private static byte[] toByteArray(final int[] data, final boolean includeLength) {
int n = data.length << 2;
if (includeLength) {
final int m = data[data.length - 1];
n -= 4;
if ((m < n - 3) || (m > n)) {
return null;
}
n = m;
}
final byte[] result = new byte[n];
for (int i = 0; i < n; ++i) {
result[i] = (byte) (data[i >>> 2] >>> ((i & 3) << 3));
}
return result;
}
//endregion
}
