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. 
package org.bouncycastle.crypto.params;

import org.bouncycastle.crypto.CipherParameters;

public class RC5Parameters
    implements CipherParameters
{
    private byte[]  key;
    private int     rounds;

    public RC5Parameters(
        byte[]  key,
        int     rounds)
    {
        if (key.length > 255)
        {
            throw new IllegalArgumentException("RC5 key length can be no greater than 255");
        }

        this.key = new byte[key.length];
        this.rounds = rounds;

        System.arraycopy(key, 0, this.key, 0, key.length);
    }

    public byte[] getKey()
    {
        return key;
    }

    public int getRounds()
    {
        return rounds;
    }
}