Crypto.java

package common;

import java.util.Base64;
import java.util.Random;

public class Crypto {

	public static String base64encode(String text) {
		return Base64.getEncoder().encodeToString(text.getBytes()); 
	}

	public static String base64decode(String text) {
		return new String(Base64.getDecoder().decode(text));
	}
	
	public static String encrypt(String message, long seed) {
		return base64encode(xorMessage(message, seed));
	}

	public static String decrypt(String message, long seed) {
		return xorMessage(base64decode(message), seed);
	}

	private static char rndChar(Random r) {
		int rnd = (int) (r.nextDouble() * 52);
		char base = (rnd < 26) ? 'A' : 'a';
		return (char) (base + rnd % 26);
	}

	public static String xorMessage(String message, long seed) {
		try {
			if (message == null)
				return null;
			char[] mesg = message.toCharArray();
			Random r = new Random(seed);
			for (int i = 0; i < mesg.length; i++) {
				mesg[i] = (char) (mesg[i] ^ rndChar(r));
			}
			return new String(mesg);
		} catch (Exception e) {
			return null;
		}
	}

}