Obfuscate Text

I have a need to obfuscate some URL paramater values:

http://www.domain.com/?campaign_name=my_campaign01

I'd like to apply a formula to obfuscate the 'my_campaign01' part and I'm looking to do a little brainstorming here in the forums. Doesn't need to be anything fancy - just need to make it so that 'wandering eyes' won't be able to clearly see 'oh that's my_campaign01'

The inputs (e.g. my_campaign01) will be unique and I need the outputted values to also be unique.

Thought about writing a long SUBSTITUTE() that would take all the vowels and replace each one of them with a pre-defined integer but I wanted to make sure I'm not overlooking something obvious here.

Thanks
James

Originally Posted by MarvinP

How about using a User Defined Function (UDF) to reverse the text?

http://www.ozgrid.com/VBA/ReverseCell.htm

Great suggestion! That actually works pretty well ~85% of the time. Unfortunately depending on the input string, sometimes it's not 'random' enough and is easily decipherable - especially ones with fewer characters.

Any other tips? Base64 encoding would be great but it uses characters in the output that would break a URL, Hex is a bit better if i could wrap it a VBA function somehow.

Originally Posted by shg

How about a simple character-substitution cipher?

That's exactly what I'm trying to do. I was hoping there was a built-in function in excel to do something like this without having to code my own from scratch. You know of one?

Found one here that I could probably expand on - http://stackoverflow.com/questions/2...pher-using-vba

Originally Posted by shg

Row\Col	A	B
1	C:\Users\shg\Documents\App Data - Excel\Excel14	A1: Input
2	H:\Yuhfo\aqw\Snxfzcxke\Sip Jxxc - Yflum\Dsnrj14	A2: =Vigenere(A1, "FGXECDOWUIJQBPZVLNYKRMHSTA", TRUE)
3	C:\Users\shg\Documents\App Data - Excel\Excel14	A3: =Vigenere(A2, "FGXECDOWUIJQBPZVLNYKRMHSTA", FALSE)

Function Vigenere(ByVal sMsg As String, _
                  ByVal sKey As String, _
                  Optional bEncrypt As Boolean = True) As String
    ' shg 2012, 2014

    ' Returns a string containing the Vigenere encryption or decryption of sMsg
    ' using key sKey. sKey must be a 26-character string containing the letters
    ' of the alphabet in scrambled order and nothing else.

    ' Characters in sMsg other than letters are preserved unchanged.
    ' Case is preserved.

    Dim sOut        As String
    Dim iChr        As Long   ' character index
    Dim iLtr        As Long   ' 0 to 25 for A to Z

    sOut = sMsg
    sMsg = UCase(sMsg)

    sKey = UCase(Replace(sKey, " ", ""))
    If sKey Like "*[!A-Z]*" Or Len(sKey) <> 26 Then
        Vigenere = "Invalid key!"

    Else
        sKey = sRept(sKey, Len(sMsg) \ Len(sKey) + 1)

        For iChr = 1 To Len(sMsg)
            If Mid(sMsg, iChr, 1) Like "[A-Za-z]" Then
                If bEncrypt Then
                    iLtr = (Asc(Mid(sMsg, iChr, 1)) + Asc(Mid(sKey, iChr, 1))) Mod 26
                Else
                    iLtr = (Asc(Mid(sMsg, iChr, 1)) - Asc(Mid(sKey, iChr, 1)) + 26) Mod 26
                End If
                Mid(sOut, iChr) = Chr(iLtr + IIf(Asc(Mid(sOut, iChr)) <= 90, 65, 97))
            End If
        Next iChr
        Vigenere = sOut
    End If
End Function

Function sRept(sMsg As String, n As Long) As String
    ' Mimics WorksheetFunction.Rept
    sRept = Replace(Space(n), " ", sMsg)
End Function

Awesome! Thanks, this works perfectly. One question though, is there a way to store sKey in the function so that I don't have to type out the 26 characters every time I want to use it? something so that I could just type =Vigenere(A1, TRUE) or =Vigenere(A1, False) to decrypt?

I changed it to:

HTML Code: 

And it still encrypts but doesn't seem to decrypt properly.