Re: [pkix] Proposed resolution to non-issued certificates - 2560bis

["Piyush Jain" <[e-mail]>]

> But the date when either the cert holder reported/requested or the CA
> decided or acknowledged that the cert is to be revoked is somewhat
> irrelevant for the code that is processing these data structures.
> The only point in times interesting to them is (a) when was it first
> posted/published or (b) at which time invalidity should be assumed to have
> started.

I think these statements about relevance are based on a narrow viewpoint.
One example is an application which needs to trigger an audit for all
transactions that happened between invalidity time and revocation time.
Both dates are required in this case. Just because you have not found a use
case does not make this information irrelevant. 

> What it neither says, and certainly not suggest is that an OCSP responder
> who is well aware that a certificate was never issued, should also respond
> "good".

But it clearly says that responder should return revoked for certificates
that have been revoked. 

> It actually fairly basic common sense that the description of positive
confirmations of cert issuance is complemented about negative
> confirmations  (=revoked status, due to a lack of alternative negative
confirmations) about not-issued certs.

Again, the common sense you talk about is based on set of limited use cases
- public CAs with browser clients.
You can find lot of corner cases that people like to address using OCSP. And
that is why there are response extensions. 
Here is another example - Checking the bank balance of the certificate
holder before allowing a financial transaction to go through. The negative
proof in this case does not warrant a revoked response. Instead the
information should be communicated using response extension. And if you are
wondering, this is not a fictitious use case. I know of at least one OCSP
responder that is designed for such use cases, what the vendor calls
'state-full validations'. 

What defies common sense is encouraging users to question the signature on
EE certificates and trusting the signature on responder certificates, even
though both are signed by the same authority.
And just to get the terminology right, these are not non-issued
certificates, these are certificates issued without the CA's knowledge, i.e.
fraudulently issued certificates. So even if the responder decides to return
revoked for such certificates, CA compromise is the right reason code.