java rc4_java RC4加密解密详解

package com.*;

public class RC4 {

public static String decry_RC4(byte[] data, String key) {

if (data == null || key == null) {

return null;

}

return asString(RC4Base(data, key));

}

public static String decry_RC4(String data, String key) {

if (data == null || key == null) {

return null;

}

return new String(RC4Base(HexString2Bytes(data), key));

}

public static byte[] encry_RC4_byte(String data, String key) {

if (data == null || key == null) {

return null;

}

byte b_data[] = data.getBytes();

return RC4Base(b_data, key);

}

public static String encry_RC4_string(String data, String key) {

if (data == null || key == null) {

return null;

}

return toHexString(asString(encry_RC4_byte(data, key)));

}

private static String asString(byte[] buf) {

StringBuffer strbuf = new StringBuffer(buf.length);

for (int i = 0; i < buf.length; i++) {

strbuf.append((char) buf[i]);

}

return strbuf.toString();

}

private static byte[] initKey(String aKey) {

byte[] b_key = aKey.getBytes();

byte state[] = new byte[256];

for (int i = 0; i < 256; i++) {

state[i] = (byte) i;

}

int index1 = 0;

int index2 = 0;

if (b_key == null || b_key.length == 0) {

return null;

}

for (int i = 0; i < 256; i++) {

index2 = ((b_key[index1] & 0xff) + (state[i] & 0xff) + index2) & 0xff;

byte tmp = state[i];

state[i] = state[index2];

state[index2] = tmp;

index1 = (index1 + 1) % b_key.length;

}

return state;

}

private static String toHexString(String s) {

String str = "";

for (int i = 0; i < s.length(); i++) {

int ch = (int) s.charAt(i);

String s4 = Integer.toHexString(ch & 0xFF);

if (s4.length() == 1) {

s4 = '0' + s4;

}

str = str + s4;

}

return str;// 0x表示十六进制

}

private static byte[] HexString2Bytes(String src) {

int size = src.length();

byte[] ret = new byte[size / 2];

byte[] tmp = src.getBytes();

for (int i = 0; i < size / 2; i++) {

ret[i] = uniteBytes(tmp[i * 2], tmp[i * 2 + 1]);

}

return ret;

}

private static byte uniteBytes(byte src0, byte src1) {

char _b0 = (char) Byte.decode("0x" + new String(new byte[] { src0 })).byteValue();

_b0 = (char) (_b0 << 4);

char _b1 = (char) Byte.decode("0x" + new String(new byte[] { src1 })).byteValue();

byte ret = (byte) (_b0 ^ _b1);

return ret;

}

private static byte[] RC4Base(byte[] input, String mKkey) {

int x = 0;

int y = 0;

byte key[] = initKey(mKkey);

int xorIndex;

byte[] result = new byte[input.length];

for (int i = 0; i < input.length; i++) {

x = (x + 1) & 0xff;

y = ((key[x] & 0xff) + y) & 0xff;

byte tmp = key[x];

key[x] = key[y];

key[y] = tmp;

xorIndex = ((key[x] & 0xff) + (key[y] & 0xff)) & 0xff;

result[i] = (byte) (input[i] ^ key[xorIndex]);

}

return result;

}

public static void main(String[] args) {

String inputStr = "做个好男人";

String str = encry_RC4_string(inputStr, "123456");

System.out.println(str);

System.out.println(decry_RC4(str, "123456"));

}

}