[C#.NET] MD5 Sum Help

[Ultra Frosty]

I can't figure out how to use the MD5 clases in System.Security.Cryptography. I'm trying to write a app that will get the MD5 sum of a file. There are more components to this app than just what you see, I can't figure out how to do this.

Box that should output the MD5 sum is: md5Box.Text

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using System.IO;
using System.Security.Cryptography;

partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        Stream fileOpen;
        OpenFileDialog openFileDialog1 = new OpenFileDialog();
        openFileDialog1.InitialDirectory = @"C:\";
        openFileDialog1.Filter = "All Files (*.*)|*.*";
        openFileDialog1.FilterIndex = 2;
        openFileDialog1.RestoreDirectory = true;

        if (openFileDialog1.ShowDialog() == DialogResult.OK)
        {
            if ((fileOpen = openFileDialog1.OpenFile()) != null)
            {
                HashAlgorithm e = new MD5CryptoServiceProvider();
                e.ComputeHash(fileOpen);

                 /* STUCK HERE */

            }
        }
    }
}

[spike232]

e.ComputeHash returns a byte array (should be 32 bits) if u want it to look like the standard u would see next to files on websites then u need to convert it to hex this gives u the 16 lenth string commonly found then u can put this in ur text box

to do the conversion to hex the following sample might help (its decompiled from one of my programs, cant find the source at the moment)

private string HashToString(byte[] b)
{
	string text1;
	string text2;
	string text3;
	int num1;

	text1 = "";
	text3 = "0";

	for (num1 = 0; (num1 < b.Length); num1 = (num1 + 1))
	{
  text2 = Convert.ToString(b[num1], 16);
  
  if (text2.Length != 2)
  {
 	 text2 = string.Concat(text3, text2);
  }
  
  text1 = string.Concat(text1, text2);
	}
	return text1; 
}

Edited July 23, 2004 by spike232

[Ultra Frosty]

Well, thank you but now that I have gotten farther in the code and I get this error. I don't know what to do:

Cannot create an instance of the abstract class or interface 'System.Security.Cryptography.HashAlgorithm'

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using System.IO;
using System.Security.Cryptography;

namespace WinHash
{
    partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Stream fileOpen;
            OpenFileDialog openFileDialog1 = new OpenFileDialog();
            openFileDialog1.InitialDirectory = @"C:\";
            openFileDialog1.Filter = "All Files (*.*)|*.*";
            openFileDialog1.FilterIndex = 2;
            openFileDialog1.RestoreDirectory = true;

            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                if ((fileOpen = openFileDialog1.OpenFile()) != null)
                {
                    HashAlgorithm h = new HashAlgorithm();
                    Converter cv = new Converter();
                    byte[] result = h.ComputeHash(fileOpen);
                    string hashVal = cv.HashToString(result);
                    md5Box.Text = hashVal;
                }
            }
        }
    }
    public class Converter
    {
        public string HashToString(byte[] b)
        {
            string text1;
            string text2;
            string text3;
            int num1;

            text1 = "";
            text3 = "0";

            for (num1 = 0; (num1 < b.Length); num1 = (num1 + 1))
            {
                text2 = Convert.ToString(b[num1], 16);

                if (text2.Length != 2)
                {
                    text2 = string.Concat(text3, text2);
                }

                text1 = string.Concat(text1, text2);
            }
            return text1;
        }
    }
}

[azcodemonkey]

You get it because HashAlgorithm is an abstract class. Abstract classes cannot be instantiated. You have to use the MD5CryptoServiceProvider class which inherits from MD5, which in turn inherits from HashAlgorithm.

MD5 md5= new MD5CryptoServiceProvider();

byte[] result = md5.ComputeHash( data );

[Ultra Frosty]

Thanks to both of you. My app is now complete!