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org.aoju.bus.crypto.symmetric.RC4 Maven / Gradle / Ivy
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package org.aoju.bus.crypto.symmetric;
import org.aoju.bus.core.codec.Base64;
import org.aoju.bus.core.lang.Charset;
import org.aoju.bus.core.lang.exception.InstrumentException;
import org.aoju.bus.core.toolkit.HexKit;
import org.aoju.bus.core.toolkit.StringKit;
import java.io.Serializable;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock.ReadLock;
import java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock;
/**
* RC4加密解密算法实现
*
* @author Kimi Liu
* @version 6.1.1
* @since JDK 1.8+
*/
public class RC4 implements Serializable {
private static final long serialVersionUID = 1L;
private static final int SBOX_LENGTH = 256;
/**
* 密钥最小长度
*/
private static final int KEY_MIN_LENGTH = 5;
private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
private int[] sbox;
/**
* 构造
*
* @param key 密钥
* @throws InstrumentException key长度小于5或者大于255抛出此异常
*/
public RC4(String key) throws InstrumentException {
setKey(key);
}
/**
* 加密
*
* @param message 消息
* @param charset 编码
* @return 密文
* @throws InstrumentException key长度小于5或者大于255抛出此异常
*/
public byte[] encrypt(String message, java.nio.charset.Charset charset) throws InstrumentException {
return crypt(StringKit.bytes(message, charset));
}
/**
* 加密，使用默认编码：UTF-8
*
* @param message 消息
* @return 密文
* @throws InstrumentException key长度小于5或者大于255抛出此异常
*/
public byte[] encrypt(String message) throws InstrumentException {
return encrypt(message, Charset.UTF_8);
}
/**
* 加密
*
* @param data 数据
* @return 加密后的Hex
*/
public String encryptHex(byte[] data) {
return HexKit.encodeHexStr(crypt(data));
}
/**
* 加密
*
* @param data 数据
* @return 加密后的Base64
*/
public String encryptBase64(byte[] data) {
return Base64.encode(crypt(data));
}
/**
* 加密
*
* @param data 被加密的字符串
* @param charset 编码
* @return 加密后的Hex
*/
public String encryptHex(String data, java.nio.charset.Charset charset) {
return HexKit.encodeHexStr(encrypt(data, charset));
}
/**
* 加密
*
* @param data 被加密的字符串
* @param charset 编码
* @return 加密后的Base64
*/
public String encryptBase64(String data, java.nio.charset.Charset charset) {
return Base64.encode(encrypt(data, charset));
}
/**
* 解密
*
* @param message 消息
* @param charset 编码
* @return 明文
* @throws InstrumentException key长度小于5或者大于255抛出此异常
*/
public String decrypt(byte[] message, java.nio.charset.Charset charset) throws InstrumentException {
return StringKit.toString(crypt(message), charset);
}
/**
* 解密，使用默认编码UTF-8
*
* @param message 消息
* @return 明文
* @throws InstrumentException key长度小于5或者大于255抛出此异常
*/
public String decrypt(byte[] message) throws InstrumentException {
return decrypt(message, Charset.UTF_8);
}
/**
* 加密或解密指定值，调用此方法前需初始化密钥
*
* @param msg 要加密或解密的消息
* @return 加密或解密后的值
*/
public byte[] crypt(final byte[] msg) {
final ReadLock readLock = this.lock.readLock();
readLock.lock();
byte[] code;
try {
final int[] sbox = this.sbox.clone();
code = new byte[msg.length];
int i = 0;
int j = 0;
for (int n = 0; n < msg.length; n++) {
i = (i + 1) % SBOX_LENGTH;
j = (j + sbox[i]) % SBOX_LENGTH;
swap(i, j, sbox);
int rand = sbox[(sbox[i] + sbox[j]) % SBOX_LENGTH];
code[n] = (byte) (rand ^ msg[n]);
}
} finally {
readLock.unlock();
}
return code;
}
/**
* 设置密钥
*
* @param key 密钥
* @throws InstrumentException key长度小于5或者大于255抛出此异常
*/
public void setKey(String key) throws InstrumentException {
final int length = key.length();
if (length < KEY_MIN_LENGTH || length >= SBOX_LENGTH) {
throw new InstrumentException("Key length has to be between {} and {}", KEY_MIN_LENGTH, (SBOX_LENGTH - 1));
}
final WriteLock writeLock = this.lock.writeLock();
writeLock.lock();
try {
this.sbox = initSBox(StringKit.bytes(key));
} finally {
writeLock.unlock();
}
}
/**
* 初始化Sbox
*
* @param key 密钥
* @return sbox
*/
private int[] initSBox(byte[] key) {
int[] sbox = new int[SBOX_LENGTH];
int j = 0;
for (int i = 0; i < SBOX_LENGTH; i++) {
sbox[i] = i;
}
for (int i = 0; i < SBOX_LENGTH; i++) {
j = (j + sbox[i] + (key[i % key.length]) & 0xFF) % SBOX_LENGTH;
swap(i, j, sbox);
}
return sbox;
}
/**
* 交换指定两个位置的值
*
* @param i 位置1
* @param j 位置2
* @param sbox 数组
*/
private void swap(int i, int j, int[] sbox) {
int temp = sbox[i];
sbox[i] = sbox[j];
sbox[j] = temp;
}
}
