X509CertificateHolder holder = new X509CertificateHolder(tspCertificateChain.get(0).getEncoded());
DefaultCMSSignatureAlgorithmNameGenerator nameGen = new DefaultCMSSignatureAlgorithmNameGenerator();
DefaultSignatureAlgorithmIdentifierFinder sigAlgoFinder = new DefaultSignatureAlgorithmIdentifierFinder();
DefaultDigestAlgorithmIdentifierFinder hashAlgoFinder = new DefaultDigestAlgorithmIdentifierFinder();
BcDigestCalculatorProvider calculator = new BcDigestCalculatorProvider();
BcRSASignerInfoVerifierBuilder verifierBuilder = new BcRSASignerInfoVerifierBuilder(nameGen, sigAlgoFinder, hashAlgoFinder, calculator);
SignerInformationVerifier verifier = verifierBuilder.build(holder);
timeStampToken.validate(verifier);
// verify TSP signer certificate
if (signatureConfig.getTspValidator() != null) {