encrypting a querystring

Hi

I have done a search on this and it seems to be a topic of some interest (700) views, but has not been fully explained.

I have a page which validates a username and password and then, if both are correct, the applicantid is retrieved and passed by querystring using a response.redirect. Apparently it would be wise to encrypt the applicantid when passing it.

Even if you can recommend a better way of passing the value, please could you still fully explain how to do the encryption.

<% else
strApplicantID = rsPandU("ApplicantID")
'Response.Write strApplicantID - this works
Response.Redirect "memberarea.asp?id=" & strApplicantID

Thanks, much appreciated!
Lee

What's to fully explain ???

Simply do this:


<%
. . .
. .
.
lngID = objRst("ApplicantID")
.
. .
. . .
Response.Redirect "memberarea.asp?id=" & Encrypt(lngID)
%>

Now all you need to do is create your own Encrypt function
for example:


Function Encrypt(ByVal TheString)
Dim x, i, tmp
For i = 1 To Len( TheString )
x = Mid( Thestring, i, 1 )
tmp = tmp & Chr( Asc( x ) + 1 )
Next
tmp = StrReverse( tmp )
Encrypt = tmp
End Function

You will have to create a Decrypt() function that does the opposite such as

Function Decrypt(ByVal encryptedstring)
Dim x, i, tmp, final
encryptedstring = StrReverse( encryptedstring )
For i = 1 To Len( encryptedstring )
x = Mid( encryptedstring, i, 1 )
tmp = tmp & Chr( Asc( x ) - 1 )
Next
Decrypt = tmp
End Function

NOTE: This might need some tweeking and hasn't been tested...

Hope this helps!
Sincerely

Vlince

Hi Vlince

Thanks for this.

I am trying to work out your encryption (5.30am) and I think my brain has passed it's expiry date.

I can't figure out the logistics of this - forgive me, I am new to asp.

I think that I have managed to encrypt the QS on the response.redirect. This value now gets passed by response.redirect to 'process.asp' with a link to another page called 'printinstructions.asp'.

This value now retrieved on 'process.asp' page now needs to be passed when the link is clicked. Where and how do I perform the de-encrypt? When the link is clicked before going to the page, or on body load of 'printinstructions.asp'? How do I do this?

Thanks, appreciate it!
Lee