A secure digital technology has been sought
Before now Dr Edward Felten was barred from discussing his methods because of legal threats from the music industry.
But they have now agreed to let him talk.
Record companies are hoping to use some of the technologies Dr Felten cracked to protect music sold via websites.
Automatic detection
Last year the music industry invited security experts and hackers to try and crack open the copy protection systems it was backing. Dr Felten and his supporters managed to cracked all but one.
The watermarking systems were invented to stop digital music being distributed for free, and would stop the unauthorised copying of music or prevent pirated pop being played anywhere other than on devices owned by the person who paid for it.
Dr Felten, a member of the free-speech pressure group Electronic Frontier Foundation (EFF), presented his findings in Washington DC on Wednesday.
He only unveiled details of his research after winning assurances from the Recording Industry Association of America (RIAA) that it would not take legal action. Twice before RIAA threats forced Dr Felten to postpone publicising his research. However soon after the first postponement the paper containing the research was circulating widely on the web.
The RIAA later said it never planned to sue.
Now the EFF is seeking to change in the law to allow more open discussion of security loopholes.
"You essentially prevent the good guys from discussing how to do better," said Dr Felten. "In practice it won't do to pretend the technology is secure."
Dr Felten and his co-researchers could still face criminal prosecution under a law that bans discussion of how to get past copy-protection technology.
Music fans
The watermarks were developed by the Secure Digital Music Initiative (SDMI), an umbrella group of more than 180 music, telecommunications and electronics companies.
Music is protected by adding an audio track that computers would pick up, but which music fans could not hear.
A $60,000 (£41,700) challenge was announced last September, inviting programmers to "show off your skills, make some money, and help shape the future of the online digital music economy".
Dr Felten's success highlighted how susceptible to hacking the technologies could be.
'No consensus'
The SDMI was founded in December 1998, but does not seem close to deciding on which technology to use.
After their last meeting in May, members said there was "currently no consensus" on how to move forward.
Member companies will meet again in September.
The group was set up in response to the huge popularity of websites like Napster that let music fans swap songs without paying royalties to artists and record companies.