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9103 anupam.sin 1 
package in.shop2020.serving.utils.ebs;
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/**
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 * This class enciphers or deciphers strings using the RC4 encryption algorithm.
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 *
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 * @author R. Prince - Java coded based on the original VB source by Mike
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 *         Shaffer
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 **/
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public class RC4 {
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	private byte state[] = new byte[256];
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	private int x;
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	private int y;
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	/**
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	 * Initializes the class with a string key. The length of a normal key
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	 * should be between 1 and 2048 bits. But this method doens't check the
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	 * length at all.
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	 *
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	 * @param key
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	 *            the encryption/decryption key
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	 */
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	public RC4(String key) throws NullPointerException {
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		this(key.getBytes());
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	}
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	/**
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	 * Initializes the class with a byte array key. The length of a normal key
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	 * should be between 1 and 2048 bits. But this method doens't check the
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	 * length at all.
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	 *
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	 * @param key
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	 *            the encryption/decryption key
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	 */
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	public RC4(byte[] key) throws NullPointerException {
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		for (int i = 0; i < 256; i++) {
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			state[i] = (byte) i;
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		}
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		x = 0;
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		y = 0;
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		int index1 = 0;
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		int index2 = 0;
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		byte tmp;
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		if (key == null || key.length == 0) {
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			throw new NullPointerException();
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		}
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		for (int i = 0; i < 256; i++) {
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			index2 = ((key[index1] & 0xff) + (state[i] & 0xff) + index2) & 0xff;
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			tmp = state[i];
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			state[i] = state[index2];
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			state[index2] = tmp;
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			index1 = (index1 + 1) % key.length;
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		}
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	}
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	/**
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	 * RC4 encryption/decryption.
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	 *
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	 * @param data
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	 *            the data to be encrypted/decrypted
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	 * @return the result of the encryption/decryption
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	 */
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	public byte[] rc4(String data) {
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		if (data == null) {
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			return null;
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		}
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		byte[] tmp = data.getBytes();
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		this.rc4(tmp);
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		return tmp;
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	}
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	/**
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	 * RC4 encryption/decryption.
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	 *
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	 * @param buf
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	 *            the data to be encrypted/decrypted
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	 * @return the result of the encryption/decryption
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	 */
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	public byte[] rc4(byte[] buf) {
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		// int lx = this.x;
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		// int ly = this.y;
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		int xorIndex;
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		byte tmp;
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		if (buf == null) {
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			return null;
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		}
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		byte[] result = new byte[buf.length];
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		for (int i = 0; i < buf.length; i++) {
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			x = (x + 1) & 0xff;
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			y = ((state[x] & 0xff) + y) & 0xff;
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			tmp = state[x];
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			state[x] = state[y];
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			state[y] = tmp;
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			xorIndex = ((state[x] & 0xff) + (state[y] & 0xff)) & 0xff;
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			result[i] = (byte) (buf[i] ^ state[xorIndex]);
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		}
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		// this.x = lx;
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		// this.y = ly;
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		return result;
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	}
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}