A U.S. federal magistrate judge has ordered Apple to unlock the phone used by one of the shooters in the December San Bernardino, CA attacks that killed 14 people. Apple is opposing the judge's order, and for good reason."The United States government has demanded that Apple take an unprecedented step which threatens the security of our customers," Apple CEO Tim Cook writes in an open letter explaining the company's stance on Apple's website. "We oppose this order, which has implications far beyond the legal case at hand."Specifically, the FBI is asking Apple to unlock Syed Rizwan Farook's iPhone 5C in order to gain access to potentially important evidence, such as his contacts, phone calls, photos, and iMessages.The Justice Department secured a search warrant for the phone, but investigators aren't able to gain access to its private data without fear of the phone permanently wiping that data after 10 failed login attempts. Magistrate Judge Sheri Pym of the Federal District Court for the District of Central California ordered Apple to offer reasonable technical assistance that should allow investigators to bypass this auto-erasing safety feature. Prosecutors were already able to access the data Farook had backed up to iCloud.The FBI has been battling Apple, Google, and other tech companies over the ability to gain access to encrypted data (particularly on smartphones). To do this, Apple would have to hand over the keys used to keep that data secure, which could in turn violate the privacy and security of all iPhone users. (For more about encryption and why it's important, click here .)Cook says that up until now, the company has "done everything that is both within our power and within the law" to aid government agencies in this investigation.“But now the U.S. government has asked us for something we simply do not have, and something we consider too dangerous to create," Cook says . "They have asked us to build a backdoor to the iPhone.”Kevin Bankston, director of New America’s Open Technology Institute, told The Washington Post that this is the same thing as asking Apple to "custom-build malware ." And once the government has this key, as the Electronic Frontier Foundation explains , it's entirely feasible to assume the government would use it over and over again, and then other governments would request access to this key, too. Your days of iPhone privacy — any digital privacy, really — would be completely over.It's unlikely the FBI will back down easily in this confrontation. But you can bet Apple's going to continue to fight back just as hard.