Hi all,

Up till now, some sites have protected themselves using a "captcha" test 
that involves the user recognising some squiggly letters, which cannot be 
done automatically by software, until now.
Perhaps a new test approach should be developed, which does not exclude 
vision impaired people.

Cheers,

John

John Nissen
Cloudworld Ltd - http://www.cloudworld.co.uk
maker of the assistive reader, WordAloud.
Tel: +44 208 742 3170  Fax: +44 208 742 0202
Email: [log in to unmask]



----- Original Message ----- 
From: <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, July 24, 2006 1:00 PM
Subject: [Webwatch] seattletimes.com: Researchers try to create 
newdistorted-letter test


> This message was sent to you by [log in to unmask],
> as a service of The Seattle Times (http://www.seattletimes.com).
>
> ----------------------------------------------------------------------
>
> Researchers try to create new distorted-letter test
> Full story: 
> http://seattletimes.nwsource.com/html/businesstechnology/2003147633_btcaptchas24.html
>
> By Crayton Harrison
> The Dallas Morning News
>
>
>
> DALLAS -- Computers are better than humans at a lot of complex 
> calculations, but we still have them beat on some small problems.
>
> That's why a very simple test has protected some of the world's biggest 
> Web sites for so long. Go online to perform a routine task -- buying 
> sports tickets, say, or sending an e-mail or commenting on a blog -- and 
> you'll see a picture of random squiggly letters.
>
> The Web site asks you to type the letters you see, something a computer 
> can't do without sophisticated programming. That keeps hackers from using 
> software to repeatedly enter information on the sites, sending spam 
> through online e-mail services or blogs.
>
> But the defenses are crumbling. Computer scientists are working on 
> replacements for the test, knowing that computers are learning to read 
> even the messiest scribbles.
>
> Lost ground
>
> The distorted-letter test "is getting to the point where it's almost 
> defeated" by computer scientists in the laboratory, said Luis von Ahn, a 
> postdoctoral fellow at Carnegie Mellon University's computer-science 
> department. "The ones not yet defeated by computers are really hard to 
> read for humans. But they'll be defeated pretty soon."
>
> Researchers aren't trying to beat the distorted-letter tests to ambush Web 
> sites, of course. They use it to make computers better at recognizing 
> text.
>
> But if computer scientists can figure out how to beat the tests, hackers 
> won't be far behind. The next wave of tests will have to present problems 
> that computer researchers and cybercriminals have barely begun to tackle 
> with artificial intelligence.
>
> Carnegie Mellon's research team trademarked a name for these 
> computer-or-human tests: captcha. It's an acronym that stands for 
> "Completely Automated Public Turing test to tell Computers and Humans 
> Apart." Turing refers to Alan Turing, a British logician who proposed a 
> theoretical test to judge whether computers were good at imitating humans.
>
> The current captchas have protected Web sites for a remarkably long time 
> in the ever-changing Internet world. Researchers at the pioneering search 
> engine site AltaVista created one of the first squiggly-letter tests in 
> the late '90s.
>
> "Humans are much better at recognizing patterns than computers are. A 
> 3-year-old can tell apart a man from a woman. Computers cannot do that," 
> said Andrei Broder, who was AltaVista's chief scientist at the time.
>
> Other researchers and companies began developing their own versions of the 
> test. Ticketmaster added one in 2002, and it's become an important part of 
> the company's defense against scalpers.
>
> "There are not a lot of ways, at the end of the day when a transaction is 
> being made, to tell if someone is an automated bot or a human, and this 
> helps us to identify that," said Bonnie Poindexter, a spokeswoman for the 
> ticketing agency owned by IAC/InterActiveCorp.
>
> Several varieties
>
> The character-recognition tests come in several varieties. Ticketmaster 
> uses a string of letters that don't appear to be warped much. But diagonal 
> lines crisscross around them, and the background is sometimes grainy.
>
> Google's Blogger service, on the other hand, uses no background. But the 
> letters roll and swirl as if they have been caught in a wave.
>
> There are ways to beat the text-based captchas, and not all of them are 
> high-tech. Some computer experts have done it simply by looking for 
> patterns in the random characters or the computer language used to 
> generate them. Some hackers have been rumored to pay people to enter the 
> correct information or entice them to do it by offering free pornography.
>
> But computer researchers are also beating text captchas simply by 
> developing computers that are sophisticated enough to read them. In the 
> same way that supercomputers have been developed to beat chess masters by 
> making millions of decisions in an instant, computers also can learn to 
> "read" and detect patterns by making a series of complex calculations.
>
> Fortunately, people can still find patterns in other ways that stymie 
> computers. Carnegie Mellon's Pix program, for instance, shows four 
> pictures that have relatively little to do with each other except for one 
> common element -- a cow, or a cup. Other researchers are also 
> experimenting with image-based captchas.
>
> And some sites, including the Blogger service, offer an audio alternative 
> for people with visual impairments. In the audio test, a voice speaks a 
> series of numbers over a staticky background, and the user must type the 
> correct sequence to access the site.
>
> Researchers continue to tweak the text-based captchas, too, using colorful 
> backgrounds or breaking the letters apart to fool the bots. But with every 
> change, they face the danger of making the captcha too difficult for 
> people to read.
>
> Other concerns
>
> Advocates for Web users with disabilities already are concerned that 
> captchas keep the visually impaired from accessing the sites they need.
>
> Text-based captchas have another problem. It's unclear who owns the rights 
> to the technology.
>
> When AltaVista developed its test, Broder and his team patented the idea. 
> Through several mergers and acquisitions, the patent fell into the hands 
> of Hewlett-Packard.
>
> HP no longer owns the patent, said Brigida Bergkamp, a spokeswoman for the 
> technology giant. She declined to disclose what had happened to the 
> patent.
>
> Carnegie Mellon researchers must decline requests for software code for 
> text captchas because the patent rights are unclear, von Ahn said. "We're 
> a little upset about that," he said.
>
> But it may not matter, since text captchas are becoming more and more 
> vulnerable.
>
> "We knew this was going to happen. It was just a matter of time," von Ahn 
> said.
>
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