Captchas are an idea whose time has come. As soon as new ways of disguising words are found, so are new ways of cracking the code. It seems that words that can be deciphered by humans are also (and quite unfortunately) decipherable by silicon chips known as computers.
Fortunately, the world of technology and security is always full of innovation. The folks at Microsoft Research have developed a new kind of Captcha that does not use a single word. In fact, it uses two common household pets, cats and dogs. According to their website:
Asirra (Animal Species Image Recognition for Restricting Access) is a HIP that works by asking users to identify photographs of cats and dogs. This task is difficult for computers, but our user studies have shown that people can accomplish it quickly and accurately. Many even think it’s fun!
Furthermore, the images are selected randomly from a HUGE database of cats and dogs up for adoption at Petfinder.com. In fact, on every image, there is a link to the pet on Petfinder.com, and if you find a pet that you like, you can adopt it. How cool is that?
One of the disadvantages of this system is that it takes considerably more time than a word Captcha. But it is a very effective way of blocking out spambots and automatic account creation.