A US student is being sued for showing how to get around anti-piracy technology on a new music CD.
Falling CD sales blamed on piracy by the record labels
Princeton graduate John Halderman published a paper online showing how to defeat the copy-protection software by pressing a single computer key.
This has angered the company behind the software, SunnComm Technologies, which is now planning to sue him.
It is just one of the firms working on ways to make it harder to copy and trade music over the internet.
Mr Halderman found that SunnComm's MediaMax CD-3 software could be bypassed by simply holding down the shift key on a Windows PC when a copy-protected CD was inserted into a disc drive.
This temporarily disables the autorun function on Windows, stopping a anti-piracy program from installing itself on the computer.
The software was used on a CD, Anthony Hamilton's Comin' From Where I'm From, released last month
In a statement, SunnComm said Mr Halderman had violated criminal provisions of the Digital Millennium Copyright Act, (DMCA), by revealing the secrets of the anti-piracy measures.
"SunnComm believes that by making erroneous assumptions in putting together his critical review of the MediaMax CD-3
technology, Halderman came to false conclusions concerning the robustness and efficacy of SunnComm's MediaMax technology," said the firm.
It said the company had lost more than $10 million of its market value since the report had appeared on the web.
But there are suggestions that the company may not pursue the matter.
The Daily Princeton campus newspaper has quoted SunnComm CEO Peter Jacobs as saying that a lawsuit would do little to reverse the damage done.
Mr Halderman, who is studying for a doctorate in computer science, said SunnComm had not contacted him directly.
"I'm still not very worried about litigation under the DMCA, I don't think there's any case," he said.
"I don't think telling people to press the shift key is a violation of the DMCA."
Various firms are trying to find ways of protecting future album releases from piracy.
The music industry blames a sharp fall in CD sales on digital piracy through online file-sharing services.
But so far, most technologies developed to protect music against copying have fallen short.