noTS LTV to PDF document. Error Signature defined. Must be closed in PdfSignatureAppearance - pdf

Question

I would like to sign and add LTV to yet not signed PDF.
I've copied coding from iText examples and qustions
http://developers.itextpdf.com/question/how-enable-ltv-timestamp-signature
Basic part of main method:
Security.addProvider(new BouncyCastleProvider());
EncryptPDF pdf = new EncryptPDF();
OCSPVerifier ocspVerifier = new OCSPVerifier(null, null);
OcspClient ocsp = new OcspClientBouncyCastle(ocspVerifier);
pdf.signPDF(file_src, file_temp, ocsp);
pdf.addLtvNoTS(file_temp, file_dest, ocsp);
Method signPDF has no problem with signing (or now commented encrypting). Temp file is OK.
private void signPDF(String src, String dest, OcspClient ocsp) {
try {
PdfReader reader = new PdfReader(src);
KeyStore ks = KeyStore.getInstance("pkcs12", "BC");
ks.load(new FileInputStream(cert2_src), keystore_password.toCharArray());
String alias = null;
Enumeration<String> en = ks.aliases();
while(en.hasMoreElements()) {
alias = en.nextElement();
System.out.println("alias name: " + alias);
}
PrivateKey pk = (PrivateKey) ks.getKey(alias, key_password.toCharArray());
Certificate[] chain = ks.getCertificateChain(alias);
PdfStamper stamper = PdfStamper.createSignature(reader, new FileOutputStream(dest), '\0', null, true);
// appearance
PdfSignatureAppearance appearance = stamper.getSignatureAppearance();
appearance.setImage(Image.getInstance(res_src));
appearance.setVisibleSignature(new Rectangle(172, 132, 572, 232), 1, "SignatureField");
// Certificate cert = getPublicCertificate(cert_src);
// stamper.setEncryption(new Certificate[]{cert},
// new int[]{PdfWriter.ALLOW_PRINTING}, PdfWriter.ENCRYPTION_AES_128 ); //| PdfWriter.DO_NOT_ENCRYPT_METADATA
// digital signature
ExternalSignature es = new PrivateKeySignature(pk, "SHA-256", "BC");
ExternalDigest digest = new BouncyCastleDigest();
MakeSignature.signDetached(appearance, digest, es, chain, null, ocsp, null, 0, CryptoStandard.CMS);
} catch (FileNotFoundException e){
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
In method addLtvNoTS I'm getting error "Signature defined. Must be closed in PdfSignatureAppearance." on last line stamper.close(). I'm not able to figure it out. Please, help.
private void addLtvNoTS(String src, String dest, OcspClient ocsp)
throws IOException, DocumentException, GeneralSecurityException {
PdfReader r = new PdfReader(src);
FileOutputStream fos = new FileOutputStream(dest);
PdfStamper stamper = PdfStamper.createSignature(r, fos, '\0', null, true);
LtvVerification v = stamper.getLtvVerification();
AcroFields fields = stamper.getAcroFields();
ArrayList<String> names = fields.getSignatureNames();
String sigName = names.get(names.size() - 1);
PdfPKCS7 pkcs7 = fields.verifySignature(sigName);
v.addVerification(sigName, ocsp, null,
LtvVerification.CertificateOption.WHOLE_CHAIN,
LtvVerification.Level.OCSP,
LtvVerification.CertificateInclusion.NO);
stamper.close();
}

Answer 1

Your addLtvNoTS method seems to first have been a copy of the addLtv method in the article which you then incompletely edited to become a copy of the addLtvNoTS method there.
In particular your addLtvNoTS method still contains this line from the article addLtv method
PdfStamper stamper = PdfStamper.createSignature(r, fos, '\0', null, true);
while in the article addLtvNoTS method the corresponding line is this:
PdfStamper stp = new PdfStamper(r, fos, '\0', true);
Thus, you create a PdfStamper for signing or time stamping (so iText eventually complains about you doing neither) while you should create one which is not.