Terrorismia vastaan verkossa

Dark Web's software, which Chen calls Writeprint, samples 480 different factors to identify whether the same people are posting to multiple radical forums. It can analyze everything from a fragment of an e-mail to videos depicting American soldiers blown up in Humvees and fuel tankers.

Former FBI counterterror chief Dale Watson, who noted that terrorist Web sites and communications are now analyzed manually, said the ability to sort through so much data electronically "would be a great asset in the fight against terrorism.

Writeprint is derived from a program originally used to determine the authenticity of William Shakespeare's works. It looks at writing style, word usage and frequency and greetings, and at technical elements ranging from Web addresses to the coding on multimedia attachments. It also looks at linguistic features such as special characters, punctuation, word roots, font size and color, he said.