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package com.lingdonge.crypto.encrypt;
import cn.hutool.core.util.CharsetUtil;
import cn.hutool.core.util.StrUtil;
import java.io.UnsupportedEncodingException;
import java.util.Random;
/**
* 字符串加解密算法
*/
public class EncryptionUtil {
/**
* 加密字符串，一个字符以上才有加密效果
*
* @param s 明文
* @return 密文
* @throws UnsupportedEncodingException
*/
public static String encrypt(String s) throws UnsupportedEncodingException {
// 数组拷贝
byte[] bytes = s.getBytes(CharsetUtil.CHARSET_UTF_8);
int length = bytes.length;
// 第一次首尾置换并相互异或
for (int i = 0; i < length / 2; i++) {
byte b = bytes[length - 1 - i];
bytes[length - 1 - i] = (byte) (bytes[i] ^ b);
bytes[i] = b;
}
// 随机密钥
byte[] key = new byte[2];
Random random = new Random();
random.nextBytes(key);
// 第二次相邻置换并跟密钥异或
for (int i = 0; i < length - 1; i = i + 2) {
byte b = bytes[i + 1];
bytes[i + 1] = (byte) (bytes[i] ^ key[0]);
bytes[i] = (byte) (b ^ key[1]);
}
byte[] ciper = new byte[length + 2];
System.arraycopy(bytes, 0, ciper, 1, length);
// 密钥混合
ciper[0] = key[0];
ciper[ciper.length - 1] = key[1];
return new String(ciper, "iso-8859-1");
}
/**
* 解密字符串
*
* @param s 密文
* @return 明文
* @throws UnsupportedEncodingException
*/
public static String decrypt(String s) throws UnsupportedEncodingException {
byte[] bytes = s.getBytes("iso-8859-1");
byte[] ciper = new byte[bytes.length - 2];
System.arraycopy(bytes, 1, ciper, 0, ciper.length);
int length = ciper.length;
for (int i = 0; i < length - 1; i = i + 2) {
byte b = ciper[i + 1];
ciper[i + 1] = (byte) (ciper[i] ^ bytes[length + 1]);
ciper[i] = (byte) (b ^ bytes[0]);
}
for (int i = 0; i < length / 2; i++) {
byte b = ciper[i];
ciper[i] = (byte) (ciper[length - 1 - i] ^ ciper[i]);
ciper[length - 1 - i] = b;
}
return StrUtil.str(ciper, CharsetUtil.CHARSET_UTF_8);
}
}