An executive at Microsoft Corp. has an unusual idea for beating spammers. Powerful software tools and supercomputers aren't involved, but kittens are.
Or rather, photos of kittens. Kevin Larson, a researcher at Microsoft's advanced reading technologies group, has found that asking a user to identify the subject of a photo, like a kitten, could help block spam programs.
Currently, services like Microsoft's free e-mail service Hotmail require new users to type in a string of distorted letters as proof that it's a human signing up for the account and not a computer. Called Human Interactive Proofs (HIPs), Microsoft, Ticketmaster and a host of other companies have been using the system for around five years, Larson said. He spoke in Seattle on Friday at TypeCon 2007, an annual conference put on by the Society of Typographic Aficionados for type enthusiasts and designers.
When Hotmail first started using HIPs, the number of e-mail accounts generated on the first day dropped by 20 percent without an increase in support queries, Larson said. That was a sign that the HIPs were fooling the computer programs that spammers use to automate signing up for new Hotmail accounts from which spam is sent. However, spammers learned how to tweak their programs to better recognize the HIPs, he said.
Now, it's a race for Microsoft to continue to alter its HIP system to fool the computers, which ultimately seem to catch on. Larson's group at Microsoft experiments with different ways to distort the text used in HIPs in a way that is easy for humans to read but difficult for computers.
One twist on the HIP idea that they've worked on is to display 16 or more photos and ask for identification of the photos. In an example, he suggested using pictures of cats and dogs. The problem with the concept, however, is that Microsoft would have to create a massive catalog of photos, otherwise the programmers could match the correct response with each photo in the catalog and begin to spoof the system, he said.
Audience members had a variety of ideas for ways to expand on the idea in order to try to beat the spam programs. One suggested that Microsoft continually take videos of a kitten jumping around a room, as a way to generate a nearly endless string of photos for identification.
"It's possible that kittens are the wave of the future," Larson joked.
Microsoft Research is offering a beta service of a photo recognition technology for free to Web site hosters. The service, called Asirra, receives animal photos from Petfinder.com and in exchange includes an "adopt me" button that takes visitors to a page where they can consider adopting the animal.
The Asirra project was "inspired," according to its Web page, by HotCaptcha, a similar idea that asks users to identify the attractive people in a group of photos. Asirra developers found that idea potentially offensive and subjective so tweaked it to use animal photos instead.
Another project, KittenAuth, presents photos to users and asks them to choose the ones that are kittens. Carnegie Mellon University's The Captcha Project also uses photo recognition to distinguish between humans and computer programs.
Microsoft might also be able to use short video clips instead of photos, one audience member suggested. The cost to support that method might be a concern but it could probably work, Larson said.
His group is also working on ways to improve the current letter-based HIPs for human users. "We need to figure out how to make HIPs that are more pleasant to read," Larson said. Many computer users may be familiar with the "ugly distorted texts" that HIPs use, he said. "We let the computer science people generate this text, but this is a design problem. It seems we ought to bring what we know about legibility to make things more pleasing to identify yet still stop computers," he said.
His team has thought about using beautiful calligraphy characters set against ornate backgrounds, but such letters haven't been good at fooling the computers because a program can identify the form of the letter by the thickness of the font compared to the lines in the background design and because a program can notice color differences of the font compared to the background, he said.
With 90 billion pieces of e-mail spam sent every day, according to Larson, companies like Yahoo Inc., Google Inc. and Microsoft that offer free online mail services have an incentive to try to block spam. Otherwise they pay for the resources that help send the spam.