Google has long supported hardware security keys for MFA on Google Accounts, and as of January 2023, Apple does as well for AppleID. Apple and Google have different suggestions about what kind of security keys to use. In its instructions, Google simply links to a Google search for FIDO U2F keys. Apple says you must use two "FIDO Certified" hardware security keys, referring people to the FIDO Alliance list of certified devices. This list is difficult to navigate and doesn't include all the devices we've listed above, such as the Nitrokey. Apple does, however, suggest YubiKey 5C NFC, YubiKey 5Ci, and Feitan ePass K9 NFC USB-A specifically. We haven't yet tested Apple's implementation of security key support and don't know how restrictive it might be. In addition to technical requirements, you'll need to consider compatibility. Apple's system has particular requirements about which version of iOS, iPadOS, and macOS you can use with security keys, so be sure to check them. You also need to use one of these up-to-date Apple devices to authenticate HomePod and Apple TV devices, as neither works directly with hardware security keys. Apple also requires the use of two security keys (one for a backup) while Google will let you enroll just one. One key difference between Apple and Google's implementation of security keys is that Apple warns, "If you lose all of your trusted devices and security keys, you could be locked out of your account permanently." Google, however, has a recovery process. In addition to their support for security keys for MFA, both Apple and Google have launched optional programs that place additional security measures around accounts and data. Google's Advanced Protection Program focuses on preventing account takeovers, but Apple's Advanced Data Protection for iCloud goes further, storing the encryption keys for your data on your devices. Apple doesn't require hardware security keys for Advanced Data Protection for iCloud, but you do have to enable MFA. Google requires two hardware security keys to enroll in its Advanced Protection Program.