Apple continues to tighten iOS security, and iOS 16.3 (and iPadOS 16.3, and macOS Ventura 13.2) includes support for physical security keys. In other words, a physical device can verify your Apple ID login in place of a passcode. It’s a great way to boost your security, and here’s how it works.

These keys work in tandem with two-factor authentication (2FA), so you still need your password. If you already have 2FA set up on your account, you’re familiar with logging into a new Apple device using your email address and password and then having a six-digit code sent via SMS or to another device (like an iPhone or a Mac) that you're already logged in on. The security key replaces that second step, the passcode.

The thinking is that having something physical that stays with you is more secure than a passcode, which can be guessed, brute-forced, or viewed over your shoulder. Apple says the security key provides “extra protection from targeted attacks, such as phishing or social engineering scams.” While a scam website or app might trick you into revealing a six-digit number, getting you to hand over a physical object is much harder.

If you want to start using security keys with your Apple ID, you first need to have 2FA switched on for your account. If you haven’t already enabled it, open Settings on your iPhone, then tap your name at the top, followed by Password & Security and Turn On Two-Factor Authentication. Follow the instructions for setting up a phone number to receive SMS messages, and specify any other trusted devices you want to use it with.

Generally speaking, 2FA comes into play when you log in on a new device or on a device you haven’t used for a long time—this isn’t a process you need to do every time you open your Mac or unlock your iPhone, as they’ll be designated as trusted devices. 2FA adds an extra step to the login process, in addition to a username and password, because those details can be guessed, tricked out of you, or leaked on the web.

Once you set up security keys, they become the extra step. They either plug directly into a lightning or USB port on your device, or (on iPhones only) they can communicate wirelessly via the NFC protocol. They essentially prove that you are who you say you are, giving you access to your Apple ID and all of your apps and services.