Tuesday, 3 May 2016

Creating a simple MD5 application using GTK# and Monodevelop

Let's look at building a simple application using GTK# and Monodevelop! I created this application using a Ubuntu 16.04 Xenial AMD64 Distribution of Linux running inside an Oracle VM VirtualBox on my Windows 10 Machine! First off, this article will show a very simple application written in Monodevelop IDE using GTK# to build a GUI. It resembles somewhat Windows Forms if you come from a Visual Studio background, such as I do. The application just takes some text input (plaintext) and computes a MD5 hash. Simple stuff. Defining the following form in MainWindow of the GTK# application: Moving over to the code bit, I define the following in MainWindow (Source of the form), which is the code behind:

using System;
using System.Linq;
using Gtk;
using System.Security.Cryptography;
using System.Text;

public partial class MainWindow: Gtk.Window
 public MainWindow () : base (Gtk.WindowType.Toplevel)
  Build ();
  btnMd5.Clicked += OnBtnClick;

 protected void OnDeleteEvent (object sender, DeleteEventArgs a)
  Application.Quit ();
  a.RetVal = true;

 protected void OnBtnClick (object sender, EventArgs args)
  var md5 = MD5CryptoServiceProvider.Create ();
  byte[] plainTextBytes = Encoding.UTF8.GetBytes (tbPlainText.Buffer.Text); 
  byte[] hashBytes = md5.ComputeHash (plainTextBytes); 
  var sbuilder = new StringBuilder (); 

  hashBytes.Select(x => x.ToString("x2")))); 
  tbHash.Buffer.Text = sbuilder.ToString();


The code above instantiates a MD5CryptoServiceProvder instance, then computes a hash. We get a string representation of the MD5 hash using a StringBuilder and we use ToString("x2") - which assembles a hexidecimal string for us, which is the common way to represent a MD5 hash. A MD5 hash produces 128 bits = 16 bytes = 32 hexidecimal digits. A hexadecimal value can be 0-9 and A-F = 16 different values = one half byte.

We build up our GUI using the GUI designer inside Monodevelop. The GUI designer for GTK# in Monodevelop is called Stetic.

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