http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.7. 
package org.bouncycastle.jce.provider.symmetric;

import java.util.HashMap;

import org.bouncycastle.crypto.CipherKeyGenerator;
import org.bouncycastle.crypto.engines.RC4Engine;
import org.bouncycastle.jce.provider.JCEKeyGenerator;
import org.bouncycastle.jce.provider.JCEStreamCipher;

public final class ARC4
{
    private ARC4()
    {
    }
    
    public static class Base
        extends JCEStreamCipher
    {
        public Base()
        {
            super(new RC4Engine(), 0);
        }
    }

    public static class KeyGen
        extends JCEKeyGenerator
    {
        public KeyGen()
        {
            super("RC4", 128, new CipherKeyGenerator());
        }
    }

    public static class Mappings
        extends HashMap
    {
        public Mappings()
        {
            put("Cipher.ARC4", "org.bouncycastle.jce.provider.symmetric.ARC4$Base");
            put("Alg.Alias.Cipher.1.2.840.113549.3.4", "ARC4");
            put("Alg.Alias.Cipher.ARCFOUR", "ARC4");
            put("Alg.Alias.Cipher.RC4", "ARC4");
            put("KeyGenerator.ARC4", "org.bouncycastle.jce.provider.symmetric.ARC4$KeyGen");
            put("Alg.Alias.KeyGenerator.RC4", "ARC4");
            put("Alg.Alias.KeyGenerator.1.2.840.113549.3.4", "ARC4");
        }
    }
}