Set trust = new HashSet();
trust.add(new TrustAnchor(rootCert, null));
CertPathValidator cpv = CertPathValidator.getInstance("PKIX","BC");
PKIXParameters param = new PKIXParameters(trust);
param.addCertStore(store);
param.setDate(validDate.getTime());
PKIXCertPathValidatorResult result =
(PKIXCertPathValidatorResult) cpv.validate(cp, param);
PolicyNode policyTree = result.getPolicyTree();
PublicKey subjectPublicKey = result.getPublicKey();