SRTPTransformEngine.java

/**
 * 
 * Code derived and adapted from the Jitsi client side SRTP framework.
 * 
 * Distributed under LGPL license.
 * See terms of license at gnu.org.
 */
package org.restcomm.media.rtp.crypto;

/**
 * SRTPTransformEngine class implements TransformEngine interface. It stores
 * important information / objects regarding SRTP processing. Through
 * SRTPTransformEngine, we can get the needed PacketTransformer, which will be
 * used by abstract TransformConnector classes.
 * 
 * @author Bing SU (nova.su@gmail.com)
 * 
 */
public class SRTPTransformEngine implements TransformEngine {
	/**
	 * The default SRTPCryptoContext, which will be used to derivate other
	 * contexts.
	 */
	private SRTPCryptoContext defaultContext;

	/**
	 * The default SRTPCryptoContext, which will be used to derive other
	 * contexts.
	 */
	private SRTCPCryptoContext defaultContextControl;

	/**
	 * Construct a SRTPTransformEngine based on given master encryption key,
	 * master salt key and SRTP/SRTCP policy.
	 * 
	 * @param masterKey
	 *            the master encryption key
	 * @param masterSalt
	 *            the master salt key
	 * @param srtpPolicy
	 *            SRTP policy
	 * @param srtcpPolicy
	 *            SRTCP policy
	 */
	public SRTPTransformEngine(byte[] masterKey, byte[] masterSalt, SRTPPolicy srtpPolicy, SRTPPolicy srtcpPolicy) {
		defaultContext = new SRTPCryptoContext(0, 0, 0, masterKey, masterSalt, srtpPolicy);
		defaultContextControl = new SRTCPCryptoContext(0, masterKey, masterSalt, srtcpPolicy);
	}

	/**
	 * Close the transformer engine.
	 * 
	 * The close functions closes all stored default crypto contexts. This
	 * deletes key data and forces a cleanup of the crypto contexts.
	 */
	public void close() {
		if (defaultContext != null) {
			defaultContext.close();
			defaultContext = null;
		}
		if (defaultContextControl != null) {
			defaultContextControl.close();
			defaultContextControl = null;
		}
	}

	/**
	 * Gets the <tt>PacketTransformer</tt> for RTCP packets.
	 * 
	 * @return the <tt>PacketTransformer</tt> for RTCP packets
	 */
	public PacketTransformer getRTCPTransformer() {
		return new SRTCPTransformer(this);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see net.java.sip.communicator.impl.media.transform.
	 * TransformEngine#getRTPTransformer()
	 */
	public PacketTransformer getRTPTransformer() {
		return new SRTPTransformer(this);
	}

	/**
	 * Get the default SRTPCryptoContext
	 * 
	 * @return the default SRTPCryptoContext
	 */
	public SRTPCryptoContext getDefaultContext() {
		return this.defaultContext;
	}

	/**
	 * Get the default SRTPCryptoContext
	 * 
	 * @return the default SRTPCryptoContext
	 */
	public SRTCPCryptoContext getDefaultContextControl() {
		return this.defaultContextControl;
	}
}