SignatureValidator.validate(lastSignature, reader, rootCertificates);
// Get OCSP responses and CRLs from DSS to validate old signatures.
PdfDictionary dictionary = reader.getCatalog().getAsDict(PdfName.DSS);
if (dictionary == null) {
throw new NoDSSException(messages.getString(
"Document_has_no_DSS_(Document_Security_Store)."));
}
PdfArray ocspArray = dictionary.getAsArray(PdfName.OCSPS);
ArrayList<BasicOCSPResp> ocsps = new ArrayList<BasicOCSPResp>();
if (ocspArray != null) {