in reply to A little fun with merlyn

Curiously enough, not only does this circumvent merlyn's anti-bot scheme, but (based on the last article I read about PayPal) it could potentially be used to circumvent an important PayPal fraud-prevention scheme that uses a GIF with numbers and letters that a user must type in during a transaction.

The scheme was considered a brilliant accomplishment by industry observers, and widely attributed to the almost instant cessation of certain kinds of fraud on PayPal.

Apparently the bad guys haven't heard of Perl. Of course, a real monk would only use Perl for goodness and the greater benefit of mankind.

P.S. Sorry I don't have a reference to the article mentioned above. It was in some Newsweekesque magazine I was browsing in the gym ....

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Re: Re: A little fun with merlyn
by Dog and Pony (Priest) on Mar 06, 2002 at 08:51 UTC
    it could potentially be used to circumvent an important PayPal fraud-prevention scheme that uses a GIF with numbers and letters

    I must say that I find that highly unlikely. Take a look at Paypal registration to see an example of the images generated - even though I am a firm beleiver that anything can be written in perl, eventaully, this really funny little trick isn't coming close to breaking the paypal images. Nor was it intended to, of course. :)

    Reading a character in an image is old news as such, so paypal uses a lot of different "blurring" techniques, such as drawing lines at random intervals, moving the characters inside the image and using a font that is hard to interpret - and probably other things too.

    Just so any paypal users can sleep a little tonight...

    You have moved into a dark place.
    It is pitch black. You are likely to be eaten by a grue.
[reply]
      Interesting. I wonder if it might be possible to use something like a hopfield network to defeat such schemes. Ages ago, I wrote a simple implementation, and it's available here, but that code is probably both ugly and not as algorithmically good as it could be.
[reply]

In Section Cool Uses for Perl