unlimited number of supported keys. This drives the requirement that
the key handle be supplied for each signature operation. U2F tokens
primarily use ECDSA signatures in the NIST-P256 field, though the FIDO2
-standard specified additional key types include one based on Ed25519.
+standard specifies additional key types, including one based on Ed25519.
SSH U2F Key formats
-------------------
sk-ssh-ed25519@openssh.com
sk-ssh-ed25519-cert-v01@openssh.com
-These key types are supported only for user authentication with the
-"publickey" method. They are not used for host-based user authentication
-or server host key authentication.
-
While each uses ecdsa-sha256-nistp256 as the underlying signature primitive,
keys require extra information in the public and private keys, and in
the signature object itself. As such they cannot be made compatible with