Sample PDF download: https://drive.google.com/file/d/12wv1Pb7gh4vCKOGhX4cZ3aOrLSiOo4If/view?usp=sharing
So when the PDF is opened in A.Reader (Contineous release) it says the Certificate is invalid as Changes have been made to this document that rendered the signature invalid.
But I can't see what/where is changed. Only a Signature (certificate) was added with our own application that adds correct signatures for thousands of other PDFs. No other changes performed. Verifying the Hash with our own code or using PDFBox2 with following code says the signature is valid (true).
So why is A.Reader complaining?
Any help much appreciated as I'm banging my head to the wall for some days now...
public static void main(String [] args) throws IOException, CMSException, OperatorCreationException, CertificateException
{
System.out.println("\nValidate signature in SignatureVlidationTest.pdf; original code.");
byte[] pdfByte;
PDDocument pdfDoc = null;
SignerInformationVerifier verifier = null;
try
{
pdfByte = FileUtils.readFileToByteArray(new File(FOLDEROUT, "102089-5913E701-5EE6-AC3F-7B03-A8D27A7CD9FA.pdf"));
pdfDoc = PDDocument.load(new File(FOLDEROUT, "102089-5913E701-5EE6-AC3F-7B03-A8D27A7CD9FA.pdf"));
// pdfDoc = Loader.loadPDF(new ByteArrayInputStream(pdfByte));
PDSignature signature = pdfDoc.getSignatureDictionaries().get(0);
byte[] signatureAsBytes = signature.getContents();
byte[] signedContentAsBytes = signature.getSignedContent(pdfByte);
CMSSignedData cms = new CMSSignedData(new CMSProcessableByteArray(signedContentAsBytes), signatureAsBytes);
SignerInformation signerInfo = (SignerInformation) cms.getSignerInfos().getSigners().iterator().next();
X509CertificateHolder cert = (X509CertificateHolder) cms.getCertificates().getMatches(signerInfo.getSID())
.iterator().next();
verifier = new JcaSimpleSignerInfoVerifierBuilder().setProvider(new BouncyCastleProvider()).build(cert);
// result if false
boolean verifyRt = signerInfo.verify(verifier);
System.out.println("Verify result: " + verifyRt);
}
finally
{
if (pdfDoc != null)
{
pdfDoc.close();
}
}
}
