[Cryptography] Is storing a hash of a private key a security risk?

[Peter Gutmann]

Ron Garret <ron at flownet.com> writes:

>Why not just sign an empty string and verify that the signature verifies
>against the public key?

That was the means of last resort, I was trying to avoid that because I'm not
sure whether there aren't some sort of controls on signing, i.e. whether you
can just perform a signing op without user interaction/authorisation.  Also
creating a capability to perform an arbitrary signature on something may not
be a good idea, an attacker may be able to leverage it to sign something of
value rather than just test data or an empty string (the hardware doesn't know
what it signs, it just gets a command "perform a sig.operation").

Peter.