For IOActive's CEO Josh Pennell, the threat of a lawsuit filed by HID seemed to be a real possibility, he told reporters during a conference call on Tuesday. The technology giant has claimed that teaching others about RFID devices violates two of the company's patents, Pennell said. On the advice of lawyers, IOActive's chief would not describe other details about the claims.

"If I say anything, HID will sue us," he said. "Large companies have lots of resources, and small companies, such as IOActive, don't."

The relevant presentation has been ripped out of the conference proceedings, according to Jeff Moss, the founder of Black Hat. The presentation will be replaced with a policy discussion about RFID insecurity and national identification.

"This is not the first time that computer professionals have been threatened by lawsuits," said Nicole Ozer, technology and civil liberties policy director at the American Civil Liberties Union (ACLU) of Northern California. "We feel that discouraging IOActive ... may have the most grave consequences."

Ozer pointed out that, on Friday, the U.S. Department of Homeland Security is scheduled to present the specifications for next-generation driver's licenses and could include RFID technology,. The inclusion of the problematic technology could result in U.S. citizens having their information stolen, leading to identity fraud and possibly endangering people.

"At this junction, it is particularly important that the government and consumers have all the information possible regarding RFID security," Ozer said.

The Black Hat Federal Conference starts on Wednesday.

UPDATE: The article was updated on Tuesday at 12 p.m. PST with comments from Kathleen Carroll, HID's director of government relations. The article was originally posted around 9:30 a.m. PST.