You may not think much about encryption day to day, but it’s the reason the FBI can't easily get at the data on the iPhones that come into its possession; it also means if someone steals your phone, they won't be able to get anything off it without the PIN code.

In terms of individual apps, it stops anyone from snooping on your WhatsApp and Signal conversations when they’re in transit from one device to the other—and that includes anyone who works at WhatsApp or the Signal Foundation. In short, it makes it much, much harder for anyone to get at your photos, messages, documents, and everything else you've got stored on your phone. Here’s how to make sure it’s working for you.

iPhone Encryption

It was the 2014 release of iOS 8 that encrypted every iPhone back to the 4S by default. Much to the chagrin of various law enforcement agencies, that encryption has only gotten tougher over time.

Everything on an iPhone is locked down as soon as you set a PIN code, a Touch ID fingerprint, or a Face ID face—your PIN, fingerprint, or face acts as the key to unlock the encryption, which is why you're able to read your messages and view your files as soon as your phone is unlocked.

This is also why you should never leave your phone lying around unlocked if you value the data on it. You can configure the screen lock on your iPhone by going to Face ID & Passcode—or Touch ID & Passcode—on the iOS Settings menu. If you go the PIN route, use at least a six-digit alphanumeric code. Anything shorter, or using numbers only, is too easy for forensic devices to brute-force.

Encryption extends to backups of your iPhone made through Apple's own software too, whether that's on the web in iCloud, or in iTunes or Finder on a connected computer. (Tap your name at the top of the iOS Settings screen, then iCloud and iCloud Backup to set which one you're using.) You can choose to leave local iTunes or Finder backups unencrypted if you want, via the tick box labeled Encrypt local backup on the Summary or General tab.

iCloud backups are encrypted, but Apple can potentially get at them if needed. Courtesy of Apple

However, there’s a crucial distinction between data on your iPhone and data in your iCloud backups. While the latter are encrypted and thus protected against hackers, Apple does hold its own key to decrypt them and will pass the data on to law enforcement if forced to. Apple will also use it to help you regain access to your backup if you lose it. If that’s a concern for you, keep your backups stored locally on a Windows or Mac laptop.

Android Encryption

The encryption picture used to be patchy for Android, but in the past three or four years most new Android smartphones—including the popular Samsung Galaxy and Google Pixel lines—have come with encryption enabled by default. You can check this under Advanced and Encryption and Credentials in the Security page of Settings.