JMF and audio encryption

Question

Hello,
I have successfully compiled and run a JMF program to transmit/receive RTP streams by re-using example programs in the API guide.
I am fairly new in this area. I would like to figure out how audio encryption works. Can someone point me to somewhere where I can give a head start on this? I guess first thing I want to understand what is the general approach to the encryption in RTP. Do I have to create a custom AudioFormat so that only my program play it?
Or is it possible to encrypt the default packets using some key and encryption algorithm? The picture in my mind is that once audio is captured and ready to be transmitted over, I would like call some method which encrypts the packets and hence once receiver receives the packets, it first decrypts the packets and then does whatever it supposed to do..
Any help, pointer, example code is appreciated.
Thanks!

Answer 1

Thanks for the answer.
Looking at the example at the link you provided, AVTransmit3.java is pretty similar to what I have in the program.
As far I can see write() method, in RTPSocketAdapter.java, does the actual data transfer in this example. However, in my program, start() in AVTransmit.java is called do start the tranmission. In start () method, processor.start() is called. Here is the code for that:
     * Starts the transmission. Returns null if transmission started ok.
     * Otherwise it returns a string with the reason why the setup failed.
    public synchronized String start() {
        String result;
        // Create a processor for the specified media locator
        // and program it to output JPEG/RTP
        result = createProcessor();
        if (result != null)
            return result;
        // Create an RTP session to transmit the output of the
        // processor to the specified IP address and port no.
        result = createTransmitter();
        if (result != null) {
            processor.close();
            processor = null;
            return result;
        // Start the transmission
        processor.start();
        return null;
    }Could I do what I want in a simple way without using sockets? Could I modify createTransmitter() to achieve this?
Would it be possible to encrypt dataOutput before caaling createSendStream? Or does it not even make sense?
sendStream = rtpMgrs.createSendStream(dataOutput, i);
    private String createTransmitter() {
        // Cheated.  Should have checked the type.
        PushBufferDataSource pbds = (PushBufferDataSource)dataOutput;
        PushBufferStream pbss[] = pbds.getStreams();
        rtpMgrs = new SessionManager[pbss.length];
        SessionAddress localAddr, destAddr;
        InetAddress ipAddr;
        SendStream sendStream;
        int port;
        SourceDescription srcDesList[];
        for (int i = 0; i < pbss.length; i++) {
            try {
                rtpMgrs[i] = new RTPSessionMgr();          
                srcDesList = new SourceDescription[] {
                    new SourceDescription(
                                        SourceDescription.SOURCE_DESC_EMAIL,
                                        "[email protected]",
                                        1,
                                        false),
                    new  SourceDescription(SourceDescription.SOURCE_DESC_CNAME,
                                        rtpMgrs.generateCNAME(),
1,
false),
new SourceDescription(SourceDescription.SOURCE_DESC_TOOL,
"JMF RTP Player v2.0",
1,
false),
localAddr = new SessionAddress();
port = portBase + 2*i;
ipAddr = InetAddress.getByName(ipAddress);
destAddr = new SessionAddress(ipAddr, port,
ipAddr, port + 1);
rtpMgrs[i].initSession(localAddr, srcDesList, 0.05, 0.25);
rtpMgrs[i].startSession(destAddr, 1, null);
temp = "Started transmission channel at " + ipAddress + " " + port + "\n";
MyApp.DisplayMess(temp);
//System.err.println("Created RTP session: " + ipAddress + " " + port);
sendStream = rtpMgrs[i].createSendStream(dataOutput, i);
sendStream.start();
} catch (Exception e) {
return e.getMessage();
Thanks very much again!