java RC4加密解密详解编程语言

    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"));   
        }   
    }