Apple’s changes to the Keychain in macOS Tahoe made it more secure. However, by binding it to device-specific Secure Enclave keys, users now can’t manually copy the login Keychain and use it on another Mac.
Attacks on Mac users are getting more sophisticated over time, with AI also opening the door to even more malware and the discovery of new intrusion techniques. While Apple does work to increase the security of its operating systems and software to counter the threats, they can also become a burden to administrators.
In a blog post on September 8, Rich Trouton wrote that it wasn’t possible to manually copy login Keychain files from one Mac to another. At least, doing so and still being able to use them on the new machine.
As he explains, the login keychain is a SQLite database file stored in the user’s home folder, which you could previously copy from one Mac to a second. While you could use the file straight away on earlier versions, an update to macOS Tahoe meant that it wouldn’t work for Macs using a Secure Enclave.
The Secure Enclave guards the metadata key that protects the keychain attributes required to decrypt it. The change means that the Secure Enclave must be used whenever the login Keychain file is accessed.
The metadata key can be cached in the Application Processor for fast keychain entries. However, the Secure Enclave must be accessed for that cache to exist in the first place.
If you’ve moved the Keychain file to another Mac, it won’t have access to the Secure Enclave, and therefore won’t open.
Changed chain in macOS Tahoe
While the change is only really becoming known now, it’s something that actually happened back in March. According to Trouton and another September 10 post by Jeff Johnson, the macOS 26.4 update introduced it.
Testing confirmed that the ability to copy the file worked for macOS 26.3, including via a virtual machine. However, copying the login Keychain from a virtual machine running macOS 26.4 didn’t work, due to not being able to be read on other Macs.
Other non-login Keychain files are unaffected and can be unlocked on other Macs fine.
In an addendum on September 11, Johnson writes that this was a “ticking time bomb” that Apple included in a minor macOS update. For macOS 26.3 and earlier, Johnson explains that users could recover their login Keychain on a new Mac, but that’s not possible on macOS 26.4 by copying it over.
In an emergency and with the death of a Mac, Johnson says users would only discover the login Keychain wouldn’t work at the worst possible moment. “This is incredibly irresponsible of Apple,” he concludes.
Exceptions and workarounds
It is evident that a straight copy of the login Keychain and opening it elsewhere simply won’t work. The hardened security is there to stop malicious actors from doing just that.
However, it is only a problem if you are copying your credentials in this particular way.
For users who are restoring backups to the same Mac, they will not be affected by the issue, as it’s the same Mac. It also won’t affect anyone using Migration Assistant, though it will be a problem for administrators performing bulk migrations in a corporate environment.
Exporting items before a migration is also a way around the issue, as well as the use of custom keychains and other password managers.
For home users, taking advantage of iCloud Keychain may be the route ahead. As well as ensuring your passwords are shared to your iPhone and iPad, they can also be synchronized with your other Macs.