I’m not sure there’s a requirement for the TPM to be used. To me that would imply the private key is stored in the TPM so you couldn’t export it. But a lot of the passkey providers have remote sync available.
Which to implement, would mean they’re storing the key outside of the TPM, but using the local TPM to decrypt the secret stored outside of the TPM. IE the certificate payloads are decryptable by a variety of keys that are stored in different TPMs. There’s lots of assumptions here of course.
It would be backed up at the point of provisioning.
A TPM can be set to allow exports or block them, so if you program the TPM to export a key once and then flip the switch to block exports then you can have this kind of backups and synchronization
I’m not sure there’s a requirement for the TPM to be used. To me that would imply the private key is stored in the TPM so you couldn’t export it. But a lot of the passkey providers have remote sync available.
Which to implement, would mean they’re storing the key outside of the TPM, but using the local TPM to decrypt the secret stored outside of the TPM. IE the certificate payloads are decryptable by a variety of keys that are stored in different TPMs. There’s lots of assumptions here of course.
I imagine password managers won’t touch the TPM, but iPhones essentially work as you say. Apple has a lot of documentation for how they synchronize.
It would be backed up at the point of provisioning.
A TPM can be set to allow exports or block them, so if you program the TPM to export a key once and then flip the switch to block exports then you can have this kind of backups and synchronization