In Java, the "official" way to do encryption is to use the Java Cryptography Extension (JCE). JCE is available as a separate package for JDK 1.2 and 1.3. It is now integrated into JDK 1.4. However, JCE is too heavy for some of my projects. All I need is a simple class that can do RC4 encryption and decryption, without complicated key generation and agreement etc.

However, if you need encryption for a "real" application, I strongly recommend you to use JCE. Also, Cryptix is a free implementation of JCE that worth a try.

You can freely use the code and class for private and non-commercial purposes.

The Javadoc is available here.

To do encryption or decryption, you need to create an instance of the RC4 class with the key first. Usually, key length is between 1 to 2048 bits. But my implementation doesn't check that.

    String key = "12345";
    RC4 rc4 = new RC4(key);

To do encryption/decryption, just pass the plain text/cipher text to the rc4 method:

byte[] result = rc4.rc4(data);

With JDK 1.3.1_02 HotSpot Server VM, the speed is around 13MB/s.

To run the test, you need to have Cryptix installed and configured. For using Cryptix under JDK 1.4, remember to install the "Unlimited Strength" Jurisdiction Policy Files