Hello.I am trying to crack basic crackmes for .NET written on C# that can't undestand code.

Please,explain me some ones. Here is function of button clicking..

private void button1_Click(object sender, EventArgs e)

{

    string str = "486752416871754464";

    string str2 = "";

    while (str.Length > 0)

    {

        str2 = str2 + Convert.ToChar(Convert.ToUInt32(str.Substring(0, 2), 0x10)).ToString();

        str = str.Substring(2, str.Length - 2);

    }

What the data it converts in the body of cicle while on str2?

 

 

What is str.substring with agruments(0,2) and 0x10.ToString();?

Could someone explain this code better please?I am just newbie in classes and methods of C#

Substring is used to remove bits of a string and return that chunk. So in the case of:

str.Substring(0, 2) this means to start at index 0 of str, and take the next two characters and return them as a new string.

 

So in your case, the first time this is called it would be:

"486752416871754464".Substring(0, 2);

 

That would return a string of:

"48"

 

As for:

Convert.ToChar(Convert.ToUInt32(str.Substring(0, 2), 0x10)).ToString();

 

You need to work from the inside out. The first to happen is:

str.Substring(0, 2) which I explained above.

 

Next is:

 

Convert.ToUInt32(str.Substring(0, 2), 0x10)

 

This will convert the number returned from the Substring to a unsigned integer, using base 16 (0x10 is hex for 16).

 

Last is:

Convert.ToChar( .. ).ToString()

 

Which means to convert the number result to a char which is a single letter in C#, then convert that char to a string.

atom0s,great thanks for fast posting.I undestood your lesson