Re: [IETF-PKIX] Multiple certificates for same key?

[Trevor Freeman <trevorf@xxxxxxxxxxxxx>]

It is impossible for CA to establish whether a public key has been used in a
certificate elsewhere.
The public key bind the user to the certificate, but the it is the
certificate which hold the CA policy on the use of the certificate which is
equally important part of the process.
It is impossible to resolve this issue within the PKI alone. We should
recommend that when generating a signature for non-repudiation purposes
applications must ensure that the identity of the certificate used to sign
is part of the data protected by the signature.