title: Signature validation with CertPathValidator including CRL revocation
body: <p>In the context of validating a signature, I want to verify the validity of the signing certificate in the time when the document was signed. I realized that CRL revocation check method is not used if I especify a past date while if I used current time or null, the revocation checks works fine. I am using the next code</p>
  
  <pre><code> CertificateFactory cf = CertificateFactory.getInstance( "X.509" );
   CertPath certPath =    cf.generateCertPath( certs );
   CertPathValidator cpv = CertPathValidator.getInstance( "PKIX", "SUN" );
  PKIXParameters params = new PKIXParameters( ks );
  params.setDate( signingTime );
  params.setRevocationEnabled( true );                
  cpvResult = (PKIXCertPathValidatorResult) cpv.validate( certPath, params ); 
  </code></pre>
  
  <p>I have already enabled the system property EnabledCRLDP.
  Besides, OCSP is not an universal solution since it does not works is some certificates.</p>
  
  <p>There is some reason to not use CRL revocation method in a past time validation?</p>
  
  <p>There is some way to force to use CRL in this case?</p>