Using Attestation
-----------------

This feature is only available in YubiKey 4.3 and newer.

Attestation works through a special key slot called “f9” this comes
pre-loaded from factory with a key and cert signed by Yubico, but can be
overwritten.
After a key has been generated in a normal slot it can be attested by this
special key, this can be realised by using the yubico-piv-tool action attest:

  $ yubico-piv-tool --action=generate --slot=9a
  ...
  $ yubico-piv-tool --action=attest --slot=9a

The output of this is a PEM encoded certificate, signed by the key in slot f9.
