Get eight byte hascode from string.

[rbulph]

Following on from here, but getting to be a different topic really, so I'll start a new thread.

 

Is there any method provided by VB for obtaining an eight byte hashcode from a string? The String's GetHashCode method seems to return a hashcode of 9, 10 or 11 bytes so is not quite what I'm after. Or should I design my own?

[PlausiblyDamp]

As a console app the following should work

       static void Main(string[] args)
       {
           EncryptString("Is there any method provided by VB for obtaining an eight byte hashcode from a string? The String's GetHashCode method seems to return a hashcode of 9, 10 or 11 bytes so is not quite what I'm after. Or should I design my own?", "password");
       }

       private static void EncryptString(string text, string pass)
       {

           MD5CryptoServiceProvider hashMD5 = new MD5CryptoServiceProvider();


           DESCryptoServiceProvider des = new DESCryptoServiceProvider();
         
           byte[] hash = hashMD5.ComputeHash(Encoding.UTF8.GetBytes(pass));
           byte[] key = new byte[8];
           Array.Copy(hash, key, 8);
           des.IV = new byte[] {1,2,3,4,5,6,7,8};  
           des.Key = key;
           string res = Convert.ToBase64String(des.CreateEncryptor().TransformFinalBlock(Encoding.UTF8.GetBytes(text), 0, text.Length));
           Console.WriteLine(res);
           Console.ReadLine();
       }

Edited August 19, 2008 by PlausiblyDamp

[rbulph]

Thanks, that works fine. In converting it to VB I need to declare Key as Key(7) rather than Key(8) but presumably that's just a difference in the language.

[Nate Bross]

Yes, that is because in C# you declare an array with the number of total elements.

 

This makes an array of length 8

myClass[] c = new myClass[8];

however, when you try to access the array, you do this

c[0] = First;
c[1] = Second;
...
c[7] = Last;

 

In Visual Basic, you define an array with the maximum [zero] based value; whereas in C# you define an array with the maximum [one] based value.

 

In short

 

myClass[] c = new myClass[8];
//'' is equal to
dim c as myClass() = New myClass(7)

 

Because C# starts with the length of the array, where as VB starts with the upperbounds of the array.

 

HTH

Edited August 19, 2008 by Nate Bross

[rbulph]

Thanks for the explanation.