Confused about Apple and the FBI? What you need to know

Apple has taken on a high-profile fight with the FBI that's sparked a spirited philosophical debate on the sweeping implications to national security and personal privacy. But what would it really take for Apple and the FBI to get along?

The truth is, it's complicated. Here are the basics to get you up to speed on both sides of the argument, what's at stake, and what's still unknown as the deadline looms for Apple to comply with the courts.

What are they actually fighting about?

Apple CEO Tim Cook (left) and FBI Director James Comey.
Getty Images
Apple CEO Tim Cook (left) and FBI Director James Comey.

The FBI is in the midst of investigating a married couple who killed 14 people in a mass shooting in San Bernardino, California, in December. The pair was believed to be inspired by the terrorist group, the Islamic State or ISIS, but it's unclear how deeply the pair is tied to foreign militant groups, according to Reuters.

Messages on shooter Syed Rizwan Farook's iPhone may, or may not, shed light on their terrorist ties. But the phone is locked by a pass code, and by default, these phones are programmed to erase data after too many unsuccessful unlocking attempts. The FBI didn't want to risk trying to hack the phone and losing all the data in the process.

Read MoreWhy Apple is fighting the FBI's San Bernardino investigation

Up until now, Apple has helped the FBI with the case, the company said. But it has resisted one specific request: To make a new version of the iPhone operating system and install it on an iPhone to make it easier to unlock by trying millions of password combinations without erasing the data within.

A federal magistrate ruled Tuesday that Apple must create this highly specialized software within a certain time frame. But Apple CEO Tim Cook released a letter saying he would challenge the FBI's demands.

Read MoreThe 'esoteric' law being used to fight Apple

Here's what Apple says

  1. Apple doesn't currently have access to individuals' iPhone data. Encryption — where algorithms scramble communications into a unique code language used to transmit electronic data — protects photos, music, notes, financial information, locations and health data from hackers. Apple is "deeply committed" to safeguarding customer data, so much so that the company itself doesn't have access to your iPhone's contents. In other words, Apple argues it doesn't keep "keys" to your phone lock.
  2. Apple would have to build a new version of iOS to meet this demand. Apple has complied with subpoenas and search warrants and provided engineers to help the FBI. But this request requires a new type of tool that Apple doesn't already have: a so-called back door.
  3. There's no way to limit that new version to a single phone. Cook makes an argument that if a less-secure version of the iPhone is built, there is no way to guarantee that the government can limit it to just one phone. "Once created, the technique could be used over and over again, on any number of devices," Cook writes. "In the physical world, it would be the equivalent of a master key, capable of opening hundreds of millions of locks."
  4. There's no precedent. Apple argues that the law in question — the All Writs Act of 1789 — has not been used for the purpose of forcing a company to turn over customer data. If this case is used as precedent for future actions, it could open floodgates to expanded government oversight over all mobile phone users.

Read MoreOrder to hack iPhone for FBI 'chilling': Tim Cook

Here's what the FBI says

  1. The government lawfully seized this phone.
    The phone was known to be used by a mass murderer, was obtained with a search warrant and the phone owners' consent. This is simply a way to execute the original intent of that warrant. The phone is owned by Farook's former employer, the San Bernardino County Department of Public Health. The department has supported federal investigators' requests to search the contents of the device.
  2. Other digital searches have given hints that the pair were communicating online with terrorists.
    Searches of the pair's iCloud account indicates that the shooter was in contact with the victims prior to the shooting, and had posted allegiance to ISIS on Facebook. But Farook stopped backing up to the cloud in late October, leaving the final month of the conversations accessible only on the phone itself.
  3. Apple frequently updates their security features.
    The needed change should be well within the company's technical capabilities, given that Apple routinely patches or updates iOS to address security features, the government argues. But they need Apple's help because Apple codes use a proprietary "signature" that cannot be recreated by with government software.
  4. Apple can use another method to unlock the phone if it wants.
    The password features are what the government calls "non-encryption" parts of Apple's code. But the request allows Apple to use a "mutually preferable" technical solution on this device only. It can even be done at an Apple facility, according to court documents.

Read More Can Apple really beat the Feds on privacy?

What we still don't know

The exchange between the government and Apple has prompted a series of questions among experts who spoke to CNBC. Among them:

  1. How could Apple, and the government, not have a master key already? Various commentators have pointed out that Apple has previously unlocked iPhones in other legal cases, and it appears the government may have, too. But as far as either party has said, the technology to unlock this particular iPhone doesn't exist yet.
  2. Isn't it just one phone?
    In a briefing with reporters, a White House spokesman denied that the government is trying to press Apple to create a back door to the iPhone. Instead, they are asking for access to one device, he told Reuters. But Cook argues this approach ignores the messy realities of digital security. Is it possible to unlock just the one phone, but keep the back door from leaking?
  3. Is it even legal for Apple to refuse this?
    Some law experts say the law isn't on Apple's side. But others opine Apple could appeal the order all the way to the Supreme Court.
  4. What if other governments — or companies — do the same?
    If the U.S. government demands access to an iPhone, can other governments do the same? Will consumers around the world still trust Apple products if they know Big Brother is watching? The NSA spying accusations posited by whistleblower Edward Snowden created geopolitical tensions. It remains to be seen whether similar implications stem from the latest conflict between the world's biggest company, and one of the world's most powerful governments.

— Reuters and the AP contributed to this report.