Uncategorized – Page 7

Making progress slowly

Okay, this website has been up for a good few days now and yet I’ve not found the time to find a decent theme or start adding content.

I really need to add something at least every night. Code snippets and other stuff.

My blog will contain updates and possibly some rants from time to time, but I aim to keep this as professional as possible for the future. I might even remove WordPress and add my own CMS as I am quite familiar with GWT now and Java.

I’m about to get myself sorted for work in the morning, so if I have enough time I will add a new page to start off my showcase examples using libGDX. LibGDX is a cross platform API not just for desktop, Android and iOS, but also for HTML5. I am building up some examples in HTML using libGDX.

First post…

This site and blog is centered around mainly around myself, my programming and my interests. Nothing more, nothing less.

It appears I’ve lost approximately 6 years of content from my old free hosting company (freehostingnoads.net), which I am seriously not happy with, but I’m going to plod on.

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Project update (no code snippets tonight)

My personal project has taken a huge face lift. The original player code has been stripped and split into two classes, the media client layer and the player itself.

The media client is the heart of the player which handles the communication with the server and supplies the player with its playlist. It’s still not compete by far, but closer to what I need it to do.

The player at the moment does zip all. The intention is to have it playing a media file and then check with the media client of any updates which will adjust it’s playlist. All previous tests of the media player have been running great.

The android app is still waiting on the above media client and its communication with the server so that I can move that one forward.

Basically tonight has been refactoring a lot of code. With a lot of testing in between. So far so good, but I’ve run out of time for tonight. Two hours isn’t enough.

I’ll need some time to do some Blender work soon also.

Devices unique identifier

Now I could have just got the MAC address and used that to communicate with the server, but I wanted to take it to the extremes. Mainly because I wanted to obscure the communication with the previous methods of encryption so the server can identify which device is making a request.

For this I create a string using the devices host name and all the network interfaces connected to it with their MAC addresses. Although I might change this in the near future, at the moment, this gives a good length string for the server to identify the device.

Below is the code used to create this identity string.

    public String host;
    
    private void testMACAddress() {
        try {
            InetAddress ip = InetAddress.getLocalHost();
            
            host = ip.getHostName();

            Enumeration&ltNetworkInterface&gt networks = NetworkInterface.getNetworkInterfaces();
            while (networks.hasMoreElements()) {
                NetworkInterface network = networks.nextElement();
                byte[] mac = network.getHardwareAddress();

                if (mac != null) {
                    StringBuilder sb = new StringBuilder();
                    
                    for (int i = 0; i &lt mac.length; i++) {
                        sb.append(String.format("%02X%s", mac[i], (i &lt mac.length - 1) ? "-" : ""));
                    }
                    
                    host += " " + network.getDisplayName() + " " +  sb.toString();
                }
            }
        } catch (UnknownHostException | SocketException e) {
            System.out.println(e.getMessage());
        }
    }

As mentioned above, this identity string will then be encrypted and sent to the server. Further communication will commence if the server accepts it.

Simplex Noise in Java

Well, I finally got round to testing out the noise algorithms again. And this time in Java.

I grabbed OpenSimplexNoise class and had to add my own functions to it so that I could use ‘octaves’ and ‘persistence’ values to add roughness to it. The extra functions which handle 2D and 3D noise are:

    public double OctavePerlin2(double x, double y, int octaves, double persistence) {
        double total = 0;
        double frequency = 1;
        double amplitude = 1;
        double maxValue = 0;  // Used for normalizing result to 0.0 - 1.0
        for(int i=0;i<octaves;i++) {
            total += eval(x * frequency, y * frequency) * amplitude;

            maxValue += amplitude;

            amplitude *= persistence;
            frequency *= 2;
        }

        return total/maxValue;
    }
    
    public double OctavePerlin3(double x, double y, double z, int octaves, double persistence) {
        double total = 0;
        double frequency = 1;
        double amplitude = 1;
        double maxValue = 0;  // Used for normalizing result to 0.0 - 1.0
        for(int i=0;i<octaves;i++) {
            total += eval(x * frequency, y * frequency, z * frequency) * amplitude;

            maxValue += amplitude;

            amplitude *= persistence;
            frequency *= 2;
        }

        return total/maxValue;
    }

Then I added a UI using Swing and got it all working including adding a water level.

[ADDED] And a better image:

All I need now is to break up the calculations into blocks and run each block on its own thread when I come to using this again.

The class which creates the bitmap:

public class BufferedImageNoise {
    
    int w, h;
    long seed;
    double scale;
    
    int off_x, off_y;
    
    int octaves;
    double persistence;
    
    double water;
    
    OpenSimplexNoise noise;
    
    public BufferedImageNoise(int width, int height, long seed, double scale, int octaves, double persistence, double water) {
        w = width; h = height;
        this.seed = seed;
        this.scale = scale;
        this.octaves = octaves;
        this.persistence = persistence;
        this.water = water;
        
        off_x = off_y = 0;
        
        noise = new OpenSimplexNoise(seed);
    }
    
    public BufferedImage getImage() {
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        for (int y = 0; y &lt h; y++)
        {
            for (int x = 0; x &lt w; x++)
            {
                double value = noise.OctavePerlin2(x / scale, y / scale, octaves, persistence) + 1.3;
                
                int rgb = value &gt water ? 0x010101 * (int)((value) * 127.5) : 0x000088;
                image.setRGB(x, y, rgb);
            }
        }
        return image;
    }
}

TCP Encryption

Tonight I grabbed an old class that uses a pseudo random number generator and implemented it into the TCP client server encryption test. Both the client and server create a new Object of the class and both set the same seed. Both the client and server will grab the next byte and add the next random number to it on a read, on a write, it will subtract the next random byte.

This worked as expected. The following code is an example of a complex random number generator.

public class WLPRNG {
    
    long seed;
    
    public WLPRNG(long seed) { this.seed = seed; }
    
    public int nextInt() {
        long result = seed + 0x123defca;
        result = Long.rotateLeft(result, 19);
        result += 0xbead6789;
        result *= 0x1234567c;
        
        int temp = (int)result;
        
        result ^= 0x5ecdab73;
        result = Long.rotateLeft(result, 48);
        
        if (temp % 4 == 0) result *= 0x87650027;
        
        result += 13;
        seed = result;
        
        return (int)result;
    }

    public byte nextByte() {
        return (byte)nextInt();
    }
}

The next step for me to try out is to use and encrypted message from the client which sends the MAC address of the client using encryption, and then both the client and server will communicate using the MAC address as a key for another pseudo random number generator.

Over time, the server can update the encryption methods used by the clients.

Cryptography Secure TCP Sockets in Java

Well, I finally got round to testing out a basic encryption over TCP sockets.

First off, the main() entry looks very familiar and is easy to understand. I simply create the listening server (doesn’t spawn thread for simplicity), with the ability to safely shut it down.

Then I use the DataInputStream and DataOutputStream to send data back and forth. In this test case I sent a string which both the client and server will print to the console.

Once that was working, I extended the OutputStream and InputStream and override the read() and write() methods (shown in the code examples below). Notice that I manipulate the byte in two different ways, one by adding and subtracting and the other by XOR’ing (commented out but works). If these manipulations match up whilst data is being sent back and forth then there’s no errors.

Main class

The main class and entry point to the test which spawns the server and then runs a couple of tests:

package com.wlgfx.cryptotest;

public class CryptoServer {

    public static void main(String[] args) {
        WLCryptoServer server_run = new WLCryptoServer();
        Thread server = new Thread(server_run);
        server.start();
        
        System.out.println("Server thread started");
        
        new Thread(new WLCryptoClient("Hello world!")).start();
        
        try { Thread.sleep(500); } catch (InterruptedException ex) {}
        
        new Thread(new WLCryptoClient("Jump around and stomp your feet!")).start();
        
        try { Thread.sleep(500); } catch (InterruptedException ex) {}
        
        server_run.quitServer();
    }
}

Server class

The server code which take the input and output streams and creates new subclasses of the encryption layer classes and then creates the usual DataInputStream and DataOutputStream for the rest of the normal IO. This matched in the following code for the client.

package com.wlgfx.cryptotest;

import com.wlgfx.cryptotest.WLC.WLInputStream;
import com.wlgfx.cryptotest.WLC.WLOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class WLCryptoServer implements Runnable {
    
    private final int port = 1999;
    private boolean quit = false;

    @Override
    public void run() {
        try {
            ServerSocket socket =  new ServerSocket(port);
            socket.setSoTimeout(1000);
            
            while (!quit) {
                Socket client = socket.accept();
                
                WLOutputStream wlout = new WLOutputStream(client.getOutputStream());
                DataOutputStream out = new DataOutputStream(wlout);
            
                WLInputStream wlin = new WLInputStream(client.getInputStream());
                DataInputStream in = new DataInputStream(wlin);
                
                String text = in.readUTF();
                System.out.println("SERVER: " + text);
                out.writeUTF(text);
                
                client.close();
            }
        } catch (IOException ex) {
            System.out.println("SERVER: " + ex.getLocalizedMessage());
        }
    }
    
    public void quitServer() {
        quit = true;
    }
}

Client class

The client code is just the same as the server class code.

package com.wlgfx.cryptotest;

import com.wlgfx.cryptotest.WLC.WLInputStream;
import com.wlgfx.cryptotest.WLC.WLOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;

public class WLCryptoClient implements Runnable {
    
    private String text;
    private Socket socket;
    
    private final int port = 1999;
    
    public WLCryptoClient(String test) {
        text = test;
    }
    
    @Override
    public void run() {
        try {
            socket = new Socket("localhost", port);
            
            WLOutputStream wlout = new WLOutputStream(socket.getOutputStream());
            DataOutputStream out = new DataOutputStream(wlout);
            
            WLInputStream wlin = new WLInputStream(socket.getInputStream());
            DataInputStream in = new DataInputStream(wlin);
            
            out.writeUTF(text);
            text = in.readUTF();
            System.out.println("CLIENT: " + text);
            
            socket.close();
        } catch (IOException ex) {
            System.out.println("CLIENT: " + ex.getLocalizedMessage());
        }
    }
    
}

The encryption class

This is where you can see exactly how easy it is to manipulate the data being sent back and forth. Here I am showing you two methods, XOR and add and subtract. It’s very simple, but for heavier encryption you could look further at CSPRNG, or Crypto Secure Pseudo Random Number Generator. PRNG’s are ten a penny, from simple ones to hefty things. Take your pick. The Crypto and Secure layers are the ones you really need for truly undecipherable data communication.

package com.wlgfx.cryptotest;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class WLC {

    // NB: short inner classes are static to avoid errors
    
    public static class WLInputStream extends InputStream {

        private InputStream in;

        public WLInputStream(InputStream input) {
            in = input;
        }

        @Override
        public int read() throws IOException {
            byte a = (byte) in.read();
            a--;
            return (int) a;

            //return in.read() ^ 255; // WORKS TOO
        }
    }

    public static class WLOutputStream extends OutputStream {

        private OutputStream out;

        public WLOutputStream(OutputStream output) {
            out = output;
        }

        @Override
        public void write(int b) throws IOException {
            byte a = (byte) b;
            a++;
            out.write((int) a);

            //out.write(b ^ 255); // WORKS TOO
        }
    }
}

Console output:

run:
Server thread started
SERVER: Hello world!
CLIENT: Hello world!
SERVER: Jump around and stomp your feet!
CLIENT: Jump around and stomp your feet!
SERVER: Accept timed out
BUILD SUCCESSFUL (total time: 1 second)

Until next time

😛

Tonight I’ve sussed out the thread pooling in Java. I wanted a way of being able to queue up threads to be run, but I also wanted to allow the execution of so many threads at a time in this pool. I’ve heard about these thread pools but as of yet, not used them. I need something like this for my own project for both the server and the client.

package threadpooltest;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;

public class ThreadPoolTest {

    public static void main(String[] args) {
        ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(5);
        
        for (int i = 0; i <= 8; i++)
        {
            WorkerTest task = new WorkerTest("Task " + i);
            System.out.println("A new task has been added : " + task.getName());
            executor.execute(task);
        }
        
        System.out.println("Main thread sleeping");
        try { Thread.sleep(8000); } 
        catch (InterruptedException ex) {}
        System.out.println("Finished sleeping");
        
        for (int i = 0; i <= 10; i++)
        {
            WorkerTest task = new WorkerTest("Task " + (i + 5));
            System.out.println("A new task has been added : " + task.getName());
            executor.execute(task);
        }
        
        // THIS DOESN'T WORK
        //System.out.println("WAITING FOR TASKS TO FINISH");
        //try { executor.awaitTermination(1, TimeUnit.DAYS); } 
        //catch (InterruptedException ex) {}
        //System.out.println("FINISHED");
        
        executor.shutdown();
    }
    
}

No proper code snippet plugin yet! Grrr!

Anyway, the above code creates the thread pool which will run a max of 5 threads and queue the rest up. Just what I wanted.

package threadpooltest;

import java.util.concurrent.TimeUnit;

public class WorkerTest implements Runnable {

    private String name;
    
    public WorkerTest(String name) {
        this.name = name;
    }
    
    public String getName() {
        return name;
    }
    
    @Override
    public void run() {
        try
        {
            Long duration = (long) (Math.random() * 5);
            System.out.println("Start Task: " + name);
            TimeUnit.SECONDS.sleep(duration);
            System.out.println("Finished Task: " + name);
        }
        catch (InterruptedException e) {}
    }
}

The above is the example thread I was testing this with.

All I need now is to do the same with C++, but I’ve already found a header only project on github that does just that.

More to come…

EDIT:

I’ve also noted that the above works on Android too.

At the moment, I’m not holding my breath to see it this works with GWT.

A weekend of zero coding

Nope, not an ounce of coding.

I needed a break.

I was feeling burnt out.

Not even a ride on my motorbike because of bad guts.

And I’m not even thinking about coding tonight before I go bed because this chilled out weekend seems to have done some good for me.

Not really an update…

Another week done and a few wins at work. I’ve been writing code to display graphics for statistical data. ie. Sales targets and stuff. Most of the awkward stuff was having to accommodate for different resolutions, portrait and landscape modes and also having to calculate the font metrics. All done though although I do need to make a few adjustments to get the advanced settings to work properly.

My personal project has gone on hold until this weekend (tomorrow), because two hours on an evening is not enough time to get stuck in to it. I need thinking time more than I need coding time. And then I need debugging time.

I have noticed though over this past year, I can write a shed load of code, a good few hundred to over a thousand lines of code, before I can finally test it out and it works. Well, saying it works, it’s easier to fix the bugs when it finally comes to testing.

This weekend I want to test communication over the internet using a crypto secure pseudo random number generator, or CSPRNG. Basically the client and server socket connections will be able to communicate without the transmitted data being viewed by any outsiders. The technique is quite simple, it’s the implementation of it and how it is handled that needs to be secured. Other systems use private keys, hashes, passwords, etc. A long list of security protocols. I kind of like the two stage authentication. Because this will be running through four pieces of software, I’ve devised a two way security system. Only access is allowed from the outside from my PC (if that is my work station) or my phone. And then, if this takes off, text message stage too. It boils down to a ‘real’ MAC address and the ‘fake’ MAC address. TCP communications can hopefully solve this by authenticating a number of things.

Anyway… I’m tired. Beers are knocking me out, and as usual, not my brain cell. So good night…

PS. Any up-scaling in the future I’ve made a few mental notes.

A day spent programming

Yep, a day of blitzing code.

There’s a total of four pieces of software I’m writing for this project. The server. The media manager. The device manager. And the device player. All four of them are now well on the way to being tested out soon enough.

So far the server works flawlessly with the media manager which can run on any OS, ie Linux, Windows or Mac.

The player is for embedded Linux only and also has some in built security layers.

The device manager runs on Android which makes it so much easier when setting up the devices.

The next step is to get the device player software to handle communication with the server and retrieve its playlist and it’s all ready for the big demo.

Once the demo setup has been produced I can move on to adding all the security layers in which will include encrypted communications over the internet.

Blender progress

I’ve got the mother-in-law down for a few days so programming after work is out because I can’t ‘zone’ with all the conversations going on.

This hasn’t stopped me from working with Blender to increase my skills with it though.

I can now easily import 3D models and animate them. Slamming text and jiggling them around is very easy too. All in all, another good demonstration video produced in a little over an hour. Fast moving 3D animated text and models with a video textured background. I’ve impressed myself this time. No stopping me now.

The server software and the Android app development will continue within the next two days when I can ‘zone’ again. There’s not much left to do on the media management software. Then there’s the device management through an android app. I’m also looking into SSL and other cryptography methods for secure communication all round.

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