Encrypter in VB

TerrorFirmer

Hi,

I'm looking to write a program that will encrypt a given string using caesar cipher code. Can somebody explain or link to how it works (in general), and why I need a key rather then just an input and output box etc....

thanks.

Evil Phil

http://www.google.ie/search?hl=en&q=caesar+cipher+code+vb.net&btnG=Search&meta=

Why ceaser cipher? There's plenty of good encryption algorithms available with .net.

TerrorFirmer

Thanks phil. It's an assignment, so it has to be caeser. But as with all my other programs rather then just copy somebody elses code I want to understand how it works!

It's VB6 I'm using.

Anyway, I've written my code now (mostly, had a tutorial this morning for help). Except...as dumb as this sounds I don't know how to get my sub function to write the results back to my main text box??

Evil Phil

Change the sub to a function of type string, here's a rough example (I'm not a vb coder anymore):

private sub DoesSomething()

    TextBox1.Text = foo();

end sub

private function foo() as string
    
   foo = "hello world"

end function

TerrorFirmer

Private Sub cmdEn_Click()
Dim key As Integer, plain As String, cipher As String

key = Val(txtKey.Text)
plain = txtInput.Text

If key >= 0 And key <= 25 Then
cipher = Encrypt(plain, key)
txtInput.Text = cipher
Else
txtInput.Text = "The key must be between 0 and 25, thanks."
End If

txtInput.Text = ??? (this part I'm stuck with, reading back info from the function)

End Sub

Private Sub cmdExit_Click()
End
End Sub


Private Function Encrypt(plaintext As String, code As Integer)
Dim i As Integer
Dim char As String
Dim temp As String
Dim temp_asc As Integer

For i = 1 To Len(plaintext)
char = Mid(plaintext, i, 1)
If asc_char >= 97 And asc_char <= 122 Then
temp_asc = Asc(char) + code
If temp_asc > 122 Then
temp_asc = 96 + (temp_asc - 122)
End If
temp = temp & Chr(temp_asc)
Else
temp = temp + char
End If
Next i

Encrypt = temp
End Function

I have this - how do I get read back the info from the private function to my main procedure...:o

Evil Phil

Your already doing it in the code you posted. Are you sure this is your code?!

TBH I'm not going to tell you as it's easily googled an you'll learn more if you work it out for yourself.

TerrorFirmer

Yes it is my code, written with my lab tutor yesterday but I didn't check it before the class ended! Except it doesn't work - so I don't know how I'm supposed to get the encrypted string BACK to the main procedure! I've tried googling it but I can't find anything to help...

edit: Oh wait I actually see now, sorry - it's already there with the textinput = cipher......sorry I don't know how I missed that part. Any ideas why it isn't working?

Evil Phil

Set a breakpoint at the start (Private Sub cmdEn_Click()) and step through you code, you should be able to work it out yourself. The VS help file will tell you how to do that, I can't remember how its done in vb6.