Damien Miller ( djm@ ) posted to tech@:

Hardware backed keys can be generated using "ssh-keygen -t ecdsa-sk" (or "ed25519-sk" if your token supports it). Many tokens require to be touched/tapped to confirm this step. You'll get a public/private keypair back as usual, except in this case, the private key file does not contain a highly-sensitive private key but instead holds a "key handle" that is used by the security key to derive the real private key at signing time. So, stealing a copy of the private key file without also stealing your security key (or access to it) should not give the attacker anything. Once you have generated a key, you can use it normally - i.e. add it to an agent, copy it to your destination's authorized_keys files (assuming they are running -current too), etc. At authentication time, you will be prompted to tap your security key to confirm the signature operation - this makes theft-of-access attacks against security keys more difficult too. Please test this thoroughly - it's a big change that we want to have stable before the next release. -d