SAN FRANCISCO - A hacker who as a teen cracked the encryption on DVDs has found a way to unlock the code that prevents iPod users from playing songs from download music stores other than Apple Computer Inc.'s iTunes, his company said on Tuesday.

Jon Lech Johansen, a 22-year-old Norway native who lives in San Francisco, cracked Apple's FairPlay copy-protection technology, said Monique Farantzos, managing director at DoubleTwist, the company that plans to license the code to businesses.

"What he did was basically reverse-engineer FairPlay," she said. "This allows other companies to offer content for the iPod."

At the moment, Apple aims to keep music bought from its iTunes online music store only available for Apple products, while songs bought from other online stores typically do not work on iPods.

But Johansen's technology could help rivals sell competing products that play music from iTunes and offer songs for download that work on iPods as they seek to take a bite out of Apple's dominance of digital music.

ITunes commands an 88 percent share of legal song downloads in the United States, while the iPod dominates digital music player sales with more than 60 percent of the market.

Cupertino, California-based Apple, whose profits have soared in recent years on the strength of the iPod, declined to comment.

Johansen, known as DVD Jon, gained fame when at the age of 15 he wrote and distributed a program that cracked the encryption codes on DVDs. This allowed DVDs to be copied and played back on any device.

His latest feat could help companies such as Microsoft Corp., Nokia, Sony Ericsson and Samsung Electronics Co. Ltd., which have all announced plans over the past few months for music download services combined with new devices to challenge Apple.