Finjan has filed a lawsuit against rival Secure Computing, alleging that a key security patent has been infringed by the company.

Filed in the United States District Court for the District of Delaware, the suit seeks an injunction against Secure Computing and its Webwasher and CyberGuard subsidiaries.

It was described by Finjan in very general terms as relating to "systems and methods for protecting a computer and a network from hostile downloadables and/or malicious code."

One unusual feature of the patent is that it goes back to a 1996 filing, shortly after Finjan was founded and long before many of the security threats covered by the patent even existed. This might, or might not, affect its viability.

“Finjan has filed the suit as a last resort,” said company CTO Yuval ben-Itzhak, who was nevertheless unable to confirm whether the company had made direct contact with Secure Computing to resolve the issue prior to the court filing.

He indicated that information regarding the alleged patent infringement came from “customers and partners” but would not comment more specifically.

The core of the complaint is believed to relate to Secure’s Webwasher software and appliance, and its effect on technology used in Finjan’s core family of web security appliances.

A UK spokesperson for Secure Computing said the first the company was aware of the issue was when Finjan filed the suit and issued its press release to journalists.