The technology works by embedding a unique ID or "fingerprint" on individual copies of multimedia content. The tool features special codes designed to withstand so-called collusion attacks that occur when multiple users conspire to electronically steal and distribute copyrighted material, said K.J. Ray Liu, professor of electrical and computer engineering at the Clark School.

In such attacks, copyrighted material such as an unreleased movie might be stolen and pieced together from multiple copies in an attempt to dilute or erase the original digital identities associated with each copy, said Liu.

'If you can find 100 people to collude together, you can reduce the fingerprint by 100 times, and nobody will be able to identify' the source of a particular leak or copyright infringement, he said.

The digital fingerprint code developed by the University of Maryland is designed specifically to resist such attempts at dilution and allows content owners to trace sources better than with other digital rights management technologies, said researcher Min Wu, an assistant professor at the school.

'A lot of the existing technology cannot really reduce the effects of collusion,' she said. 'If multiple users generate one version, we can tell you all those who contributed to it."