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Newcastle scientists help improve online security

If you’re one of the lucky people to have seen a reduction in the amount of email spam in your inbox lately, you might want to thank computer scientists at Newcastle University.

Dr Jeff Yan and PhD student Ahmad Salah El Ahmad recently became the first people to crack the security behind the biggest names in global email services, exposing widespread vulnerability. But, unlike the hackers who exploit cracks in the system for their own gain, they used their knowledge for the greater good and took their findings straight to the companies.

The security system in question is known as CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Humans Apart). Anyone surfing the web will have encountered a CAPTCHA scheme: picture of wavy, distorted letters which have to be deciphered and typed into a box before accessing secure websites.

However, in the last two year there has been a noticeable increase in spam originating from free email providers’ domains.

Dr Yan said: “There were suggestions that cheap labour was behind this increase, and that CAPTCHA security was good enough, but low-paid people in developing countries were being hired to decode it manually. Our research showed that computers, not people, were able to break this code much easier than previously thought.”

Dr Yan’s team’s methods were initially tested in 2007 on a high-profile CAPTCHA designed and widely deployed by Microsoft, with surprisingly good results. The latest CAPTCHA used by Yahoo, which was designed to be more hacker-proof, has also fallen foul of Dr Yan’s technique.

The findings were not released until the companies concerned were able to address the issues raised by Dr Yan’s research. Higher security is now in place, but making it harder for computers to solve the problem also makes it more difficult for humans to decipher. “It’s a question of striking the right balance,” said Dr Yan. “I actually think the idea of CAPTCHA is a good one, but the devil is in the detail and this is where future work needs to focus.”

This was posted in Bdaily's Members' News section by Ruth Mitchell .