RC4(加密、解密)

package com.k1.script;

public class RC4 {

    public static byte[] decry_RC4_byte(byte[] data, String key) {
        if (data==null || key == null) {
            return null;
        }
        byte[] data_code = new byte[data.length - 8];
        for (int i = 8; i < data.length; i++) {
            data_code[i - 8] = data[i];
        }
        return RC4Base(data_code, key);
    }

    public static String decry_RC4(byte[] data, String key) {
        if (data == null || key == null) {
            return null;
        }
        return asString(RC4Base(data, key));
    }

    public static byte[] decry_RC4(String data, String key) {
        if (data == null || key == null) {
            return null;
        }
        return 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)));
    }

    public static byte[] encry_RC4_bytes(byte[] data, String key) {
        if (data == null || key == null) {
            return null;
        }
        return RC4Base(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;
    }

    // 解密
    public static String HloveyRC4(String aInput, String aKey) {
        int[] iS = new int[256];
        byte[] iK = new byte[256];

        for (int i = 0; i < 256; i++)
            iS[i] = i;

        int j = 1;

        for (short i = 0; i < 256; i++) {
            iK[i] = (byte) aKey.charAt((i % aKey.length()));
        }

        j = 0;

        for (int i = 0; i < 255; i++) {
            j = (j + iS[i] + iK[i]) % 256;
            int temp = iS[i];
            iS[i] = iS[j];
            iS[j] = temp;
        }

        int i = 0;
        j = 0;
        char[] iInputChar = aInput.toCharArray();
        char[] iOutputChar = new char[iInputChar.length];
        for (short x = 0; x < iInputChar.length; x++) {
            i = (i + 1) % 256;
            j = (j + iS[i]) % 256;
            int temp = iS[i];
            iS[i] = iS[j];
            iS[j] = temp;
            int t = (iS[i] + (iS[j] % 256)) % 256;
            int iY = iS[t];
            char iCY = (char) iY;
            iOutputChar[x] = (char) (iInputChar[x] ^ iCY);
        }

        return new String(iOutputChar);

    }

}