com.jrdp.core.encryption.RC4.java Source code

Introduction

Here is the source code for com.jrdp.core.encryption.RC4.java

Source

/*
 * Copyright (C) 2013 JRDP Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jrdp.core.encryption;

import org.bouncycastle.crypto.engines.RC4Engine;
import org.bouncycastle.crypto.params.KeyParameter;

class RC4 {
    private RC4Engine engine;
    private int uses;
    private int maxUses;
    private KeyUpdateRequestListener listener;

    public RC4(byte[] key, int usesBeforeUpdate, KeyUpdateRequestListener listener) {
        updateKey(key);
        maxUses = usesBeforeUpdate;
        uses = 0;
        this.listener = listener;
    }

    public byte[] decrypt(byte[] data, int offset, int length) {
        return process(data, offset, length);
    }

    public byte[] encrypt(byte[] data, int offset, int length) {
        return process(data, offset, length);
    }

    public void warnOfUse() {
        uses++;
        if (uses >= maxUses) {
            listener.onKeyUpdateRequest(this);
        }
    }

    public synchronized void updateKey(byte[] newKey) {
        engine = new RC4Engine();
        engine.init(true, new KeyParameter(newKey));
        uses = 0;
    }

    public synchronized byte[] process(byte[] data, int offset, int length) {
        engine.processBytes(data, offset, length, data, offset);
        return data;
    }

    public interface KeyUpdateRequestListener {
        public void onKeyUpdateRequest(RC4 source);
    }
}