PKIXRevocationChecker and ocsp stapling

[Sean Mullan]

Hi,

On 6/1/19 8:29 AM, Michał Zegan wrote:
> Hello,
> I believe I have found a bug but not quite sure if it is in
> documentation or jdk impl itself. I currently have no code example, but
> I looked into the jdk code itself.
> This
> https://docs.oracle.com/en/java/javase/11/security/java-pki-programmers-guide.html#GUID-43A3A247-E165-408C-AD74-88A75BFB4750
> actually suggests that when using the own instance of
> PKIXRevocationChecker, you should disable default revocation by
> PKIXParameters.setRevocationEnabled(false)

Not completely true. You should disable revocation checking if you are 
passing in an subclass of PKIXCertPathChecker (and not 
PKIXRevocationChecker) because the JDK implementation doesn't know if it 
is a revocation checker or not. But if you pass in a 
PKIXRevocationChecker (this API was added later in JDK 1.8) it doesn't 
matter if the revocation flag is enabled or not, it will be recognized 
and get used instead of the default one.

> and it actually seems to be
> suggested by api docs too even though it is not stated there directly.

It says in PKIXParameters.setRevocationEnabled [1]:

"Sophisticated applications should set this flag to false when it is not 
practical to use a PKIX service provider's default revocation checking 
mechanism or when an alternative revocation checking mechanism is to be 
substituted (by also calling the addCertPathChecker or 
setCertPathCheckers methods)."

and in the PKIXRevocationChecker API [2]:

"When supplying a revocation checker in this manner, it will be used to 
check revocation irrespective of the setting of the RevocationEnabled flag."

(Although we should probably add a similar statement to the 
setRevocationChecker API so it is more clear).

> However:
> - first, from what I know, if revocation is enabled by
> setRevocationEnabled and a custom PKIXRevocationChecker is added, then
> this fact is respected correctly by the validator implementation, it can
> be seen in the code.

Right.

> - on the other hand, if it is disabled, then you can still add the
> checker, but for example ocsp stapling in jsse probably will stop working.
> It is because sun.security.validator.PKIXValidator's addResponses method
> works only if revocationEnabled is true.

Good catch - that looks like a bug.

> What is even more weird, the method seems to honour the fact that user
> could add his own PKIXRevocationChecker, but for it to work it has to be
> done *and* revocationEnabled needs to be true.

Yes, that should not be required.

> Seems like a confusion/inconsistency. Not quite sure if this is a bug in
> the code, or more in the documentation, and what is the correct approach.
> Note I didn't actually test this (I don't have any ocsp whatever). It is
> just what I read when looking at jdk code, so my findings could be wrong.

Thanks for spotting this. I will file a bug on your behalf.

--Sean

[1] 
https://docs.oracle.com/en/java/javase/12/docs/api/java.base/java/security/cert/PKIXParameters.html#setRevocationEnabled(boolean)
[2] 
https://docs.oracle.com/en/java/javase/12/docs/api/java.base/java/security/cert/PKIXRevocationChecker.html