Encrypt function (vb-> C#) [Resolved]

Hello
Am trying to translate a vb-encrypt function to C# but I'm stuck.

VB Code:

Dim strChar, L, x
      
      L = Len(strKey)
      For x = 1 To Len(strValue)
         strChar = Asc(Mid$(strKey, (x Mod L) - L * ((x Mod L) = 0), 1))
         Mid$(strValue, x, 1) = Chr$(Asc(Mid$(strValue, x, 1)) Xor strChar)
      Next

I have some trouble finding the correct functions for string manipulation.
mid = .substring()
chr$ = ? (is it (char) )
ASC = ? (i think it is system.text.asciiencoding)
mod = ? (cant find it in system.math)
Xor = ? (cant find it in system.math)

It's hard to translate from VB6 to C# esp . If you don't have to , then you better use the .NET way in Cryptographic class . Not that complicated . http://www.codeproject.com/csharp/Encryption.asp

We have already looked att the crypto-class but our problem is that the app we are translating saves the decrypted strings in a db and if we change the decrypt-function we cant read/save the values.

that why we have to translate it :(

aha , OK . Try to convert this VB6 code into VB.NET , when you get these functions to work , save them in a class file , ship them in a dll file , then you can *I think* use it within your C# proj .

here's how to use asc / char translations in a simple button click , this may help with some of your answers .

Code:

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private void button1_Click(object sender, System.EventArgs e)
{
        string message="my message ";
        Byte[] bt = System.Text.Encoding.ASCII.GetBytes(message);       
        for (int i=1; i!=bt.Length ; i++)
        {
        Console.Write(bt[i]); //// asc chars for each letter
        string s= System.Text.Encoding.ASCII.GetString(bt, 0, i);
        MessageBox.Show(s); /// show letter converted back from asc chars.
        }
}

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Code:

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System.Data.SqlTypes.SqlInt32.Mod

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thats the Mod function in c#

Code:

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System.Data.SqlTypes.SqlInt32.Xor

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and Xor.

mod -> % operator, ex : 3 % 1
chr -> "myString"[0] , where 0 is the chr you want to see