Image Verification in ASP
By Mike Irving - Published: 15/8/2007

Many web designers use Image Verification as a method of preventing Contact Forms from falling victim to SPAM-Bots.

What are SPAM-Bots? Put simply, machines that trawl the web looking for websites with contact forms. Once on a contact form they will attempt to fill it in with Junk or Advertising information.

Most sites will receive occasional SPAM mail from their contact form. When this becomes a common occurance, action should be taken.

Image Verification asks the user to type in a series of numbers or letters before submitting the form.

The data to be entered is presented to the user as an Image, usually slightly scrambled or on a background image, so as to stop robots from reading it.

This method will stop a good percentage of form spam from the bots. The server will only process the form, if the user data matches the data in the scrambled image.

I recently implemented image verification on an ASP website. I used MD5 Encryption to scramble the data required, to send it along with the form for comparison with the user input.

I used the ASPJpeg component from Persits Software to generate my image from a JPEG source file, with the required Image Verification text overlaid.

If you'd like to know more, please Contact Me.


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