SAN JOSE — A hacker known for cracking the copy-protection technology in DVDs claims to have unlocked the playback restrictions of Apple Computer Inc.’s iPod and iTunes music products and plans to license his code to others.

The move by Jon Lech Johansen, also known as “DVD Jon,” could pit the 22-year-old against Apple’s lawyers, experts say, but if successful could free users from some restrictions Apple and its rivals place on digital music.

Today, songs purchased from Apple’s online iTunes Music Store can’t be played on portable devices made by other companies. Songs purchased from many other online music stores also won’t work on iPods because they similarly use a form of copy-protection that Apple doesn’t support.

Johansen said he has developed a way to get around those restrictions by creating code that mimics Apple’s copy-protection system. But unlike his previous work, which he usually posts for free, the Norway native plans to capitalize on his efforts through his Redwood Shores-based DoubleTwist Ventures, said the company’s only other employee, managing director Monique Farantzos.

An unnamed client will soon use the technology so its copy-protected content will be playable on iPods, she said, declining to give any specifics.

“There’s a certain amount of trouble that Apple can give us, but not enough to stop this,” Farantzos said Tuesday. “We believe we’re on good legal ground, and our attorneys have given us the green light on this.”

Apple spokeswoman Kristin Huguet said the company was declining to comment.

A few others, including RealNetworks Inc.’s RealPlayer Music Store, have also tried to circumvent Apple’s copy-protection technology, called FairPlay, but haven’t gained much traction.

Fred von Lohmann, a staff attorney at the privacy-advocacy group, Electronic Frontier Foundation, said Johansen is treading carefully this time, consulting with lawyers, but isn’t necessarily cleared from a legal fight over copy-protection laws.

“There is a lot of untested legal ground surrounding reverse engineering,” he said.

Johansen became a hero to hackers at age 15, when he posted software called DeCSS to unlock the Content Scrambling System, or CSS, the film industry used on DVD movies to prevent illegal copying. The act made Johansen, who was then living in Norway, a folk hero among hackers.

After the film industry complained, Norwegian authorities charged him with data break-in, but Johansen was acquitted.

He has since become a strong advocate of the open-source philosophy of making software code freely available for inspection and sharing.