Background Reading

Apple, The FBI and iPhone Encryption: A Look At What's At Stake

NPR.ORG 2/17/2016

Remember the cryptex, the little handheld safe fromThe Da Vinci Codewhere entering the correct combination will reveal the secret message and entering the wrong one will destroy it?

Now replace the little safe with an iPhone, and instead of a secret message, it's holding evidence in a terrorism case. The critical combination? It's a passcode — one the FBI doesn't know, and one that Apple is reluctant to help the agency figure out.

Of course, it's more complicated than that. Here are a few key questions and answers about thedispute between the tech giant and federal investigators:

Whose phone are investigators trying to access?

In December, Syed RizwanFarook and Tashfeen Malikattacked the Inland Regional Center in San Bernardino, Calif., with guns and explosives, killing 14 people before being killed themselves in a shootout with police.

Malik had expressed support for the Islamic State on a Facebook page created under an alias, investigators say, but there are still many questions about who the two shooters might have communicated with before the attack, and what their motives were.

During the investigation, the FBI obtained an iPhone 5c used by Syed Farook. The device was a company phone, owned by Farook's employer, San Bernardino County.

Investigators have a warrant to search the phone and also have permission from the county — but the phone is protected by a passcode that the FBI does not know.

The agency has asked Apple to help it circumvent the phone's security features — a request Apple has denied. Now a federal judgehas orderedApple to cooperate, and Apple has refused.

What is the FBI looking for?

Investigators say they've already obtained the most recent backup of Farook'siCloud account — but that the iCloud account stopped updating a month and a half before the attack. That suggests there may be something valuable on the actual phone, the U.S. Attorney's Office for the Central District of California wrote in acourt filing:

"This indicates to the FBI that Farook may have disabled the automatic iCloud backup function to hide evidence, and demonstrates that there may be relevant, critical communications and data around the time of the shooting that has thus far not been accessed, may reside solely on the SUBJECT DEVICE, and cannot be accessed by any other means known to either the government or Apple."

We don't know what, if anything, the phone contains. Law enforcement can typically access some information shared through a phone — such as social media posts, Web searches, some emails and text messages — with a subpoena to telecom and tech companies. But some information, such as iMessages or WhatsApp messages, gets encrypted on the sender's phone and only gets decrypted when delivered, while other data, like photos, might never get shared with another device.