Big tech companies are joining Apple in its encryption fight

Earlier this week, a U.S. magistrate ordered Apple to help investigators break into an iPhone used by one of the San Bernardino mass shooters.

Apple has until next Tuesday to challenge that ruling, setting the stage for a legal clash that could determine whether tech companies or government authorities get the final say on just how secure devices like smartphones can be.

For months, Cook has engaged in a sharp, public debate with government officials over his company's decision to shield the data of iPhone users with strong encryption — essentially locking up people's photos, text messages and other data so securely that even Apple can't get at it.

While tech companies have spoken against broad government surveillance in the past, the Obama administration has recently sought to enlist the tech industry's help in fighting terrorism.

Several companies have recently heeded the administration's request for voluntary efforts aimed at countering terrorist postings on social media.

Cook has made privacy protection a part of Apple's marketing strategy, drawing a contrast with companies like Google and Facebook that sell advertising based on customers' online behavior.