Sliding Images Fool Spambots Without Driving You Mad

Startup Minteye says its sliding, image-based Captcha is simpler to use and a potential money maker.

Text-based Captchas help protect users from spam but are often difficult to solve.

Those squiggly jumbled letters and numbers that you’re often forced to type on a Web page to prove you’re a human and not a spam-spewing computer are a frustrating part of life online. Some of these puzzles are so tricky that you might fail a couple of times before getting them right. You might even give up and leave the page instead of completing a purchase or signing up for a new online account.

A startup called Minteye thinks it has a better solution, and one that can help websites make money: an image-based advertisement that the user has to unscramble by moving a slider across the screen. Minteye launched its product publicly this week after spending about a year testing it, and it’s currently available on a couple of hundred websites, CEO Gadi Hadar says.

A Minteye Captcha appears as a scrambled image with a small slider below it. The user has to move the slider until the image looks correct, which may happen at any point. Minteye’s software determines if you’ve moved the slider to the correct position, at which point it lets the website know that you are a human so you can continue navigating.

The Captcha was invented by Carnegie Mellon University researchers in 2000; the term is an acronym for “completely automated public Turing test to tell computers and humans apart.” These days, the technology is commonly used all over the Web. Luis von Ahn, who helped create the Captcha and later created a system that uses such tests to digitize old book texts, estimates that people solve 200 million Captchas per day.

Minteye is one of numerous companies attempting to make it easier to solve Captchas without making them easier for spammers to fool (see “Video Ads That Outwit Spammers”). When the puzzles are too hard to solve, it can lead to irritation and, at worst, lost business for websites. Minteye believes that its flavor of Captcha in particular is particularly well poised to take off as an ever-growing number of people use smartphones and tablets to navigate the Web.

The idea for Minteye came from founder Shayke Inbar, who has dyslexia and found it extremely difficult to pass standard Captcha tests. Seeking to create a similar test that used images rather than letters, he realized that using ads for those images could generate money while authenticating users.

Minteye splits ad revenue 50-50 with websites that run its Captchas. But websites can also use Minteye to just show random images, he says. Hadar says the company has a unique method for scrambling and cutting up an image. This is meant to make it more difficult for a spambot to solve.

Von Ahn isn’t convinced of Minteye’s security, saying software that moves the slider until it detects straight lines in the image “would probably have a pretty good chance at defeating this.”

But Hadar claims Minteye’s puzzles are even more secure than typed Captchas. It’s easier to build a bot that can identify letters and numbers than one to recognize images “that can be deformed in practically endless ways,” he says.

“Having said that,” he admits, “there is no Captcha in the world that cannot be cracked—it’s only the amount of resources invested in cracking.” 

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