Writing secure forms

[fluiduk]

Hi All

Working on a fairly simple shopping cart using Protx and have an issue

It might be best to outline the process at present

checkout.asp - User adds items to cart, confirms quantities etc and presses 'checkout'. This redirects them to payment.asp (via ssl) where they enter their card details etc.

payment.asp - The user enters their card details. There are some hidden form field fields also, these are retrieved from the database, i.e billing address and postcode. Once the user enters their details the form is securely posted to the Protx payment page on our server that does all the work with Protx.

The issue at the moment is that I want to secure payment.asp in that I don't want anyone to be able to view the form source code and the hidden values it contains.

The card details are posted securely to the next page so that isn't a major issue, its just people viewing the hidden fields thats an issue.

Any help appreciated as this is the first time I have tackled this kind of thing

Thanks

 

[fluiduk]

Also...

Whats the best way to secure a form... ie to stop unauthorised people trying to post to the action script?

Thanks
Aaron

 

[akakjs]

Hi,

The form can only really be secured by moving all sensitive information "server-side", the number one rule when writing a cart is never trust ANYTHING the client sends to you, always double-check.

akakjs

 

[growse]

If memory serves, protx provides some very sensible way of checking whether a session has been hijacked and different vars have been posted back to it. Something like a hash of all the data is kept and checked. But it's true - never trust anything a client sends you.

 

[fluiduk]

At the moment the only thing the client sends to the payment page is the card details and the order number.

The script retrieves the rest from the database.

Is that going to help?

 

[growse]

As long as you check that the order number is valid, that's fine. Then I imagine on the server side you figure the amount out for that order along with the billing address you've got and fire that off to protx