Sean Mullan's Blog

In JDK 7, we have added a new method (getReason) to the java.security.cert.CertPathValidatorException class which returns an object indicating the reason a certificate chain, or CertPath, is invalid. Previously, there was no standard mechanism to determine the reason of failure, and applications had to depend on the exception message or the cause which could vary based on the underlying service provider implementation.

The getReason method returns an instance of CertPathValidatorException.Reason, which is an interface. There are 2 subclasses of this interface. One is BasicReason which is an enumeration of reasons which can apply to certificate chains of any type (X.509, PGP, etc). It contains reasons such as EXPIRED (certificate has expired) or INVALID_SIGNATURE. The other subclass is PKIXReason, and that enumerates the potential PKIX-specific reasons that an X.509 certification path may be invalid according to the PKIX (RFC 3280) standard, for example UNRECOGNIZED_CRIT_EXT . Here's an example of how you might use these new APIs in your application that validates certificate chains:

CertPathValidator cpv = CertPathValidator.getInstance("PKIX");
try {
    CertPathValidatorResult cpvr = cpv.validate(path, params);
} catch (CertPathValidatorException cpve) {
    CertPathValidator.Reason reason = cpve.getReason();
    int index = cpve.getIndex();
    System.err.println("Invalid certificate chain, certificate[" + index + "], reason: " + reason);⁞  
}