I have an issue creating a valid CMS signature with Bouncy Castle using a trusted timestamp. The signature creation works well (I want to include the signature to a PDF file), the signature is valid. But after I include a trusted timestamp to the signature's unsigned attribute table, the signature still stays valid, but the Reader reports that The signature includes an embedded timestamp but it is invalid. This leads me to believe, that the hash I timestamp is not the correct one, but I cannot seem to figure out what is the problem with it.
Signing code:
Store store = new JcaCertStore(Arrays.asList(certContainer.getChain()));
CMSSignedDataGenerator signedDataGenerator = new CMSSignedDataGenerator();
JcaSignerInfoGeneratorBuilder infoGeneratorBuilder = new JcaSignerInfoGeneratorBuilder(new JcaDigestCalculatorProviderBuilder().setProvider("BC").build());
JcaContentSignerBuilder contentSignerBuilder = new JcaContentSignerBuilder("SHA1withRSA");
signedDataGenerator.addSignerInfoGenerator(
infoGeneratorBuilder.build(contentSignerBuilder.build(certContainer.getPrivateKey()), (X509Certificate)certContainer.getSignatureCertificate()));
signedDataGenerator.addCertificates(store);
CMSTypedData cmsData = new CMSProcessableByteArray(data);
signedData = signedDataGenerator.generate(cmsData, false);
Collection<SignerInformation> ss = signedData.getSignerInfos().getSigners();
SignerInformation si = ss.iterator().next(); // get first signer (should be only one)
ASN1EncodableVector timestampVector = new ASN1EncodableVector();
Attribute token = createTSToken(si.getSignature());
timestampVector.add(token);
AttributeTable at = new AttributeTable(timestampVector);
si = SignerInformation.replaceUnsignedAttributes(si, at);
ss.clear();
ss.add(si);
SignerInformationStore newSignerStore = new SignerInformationStore(ss);
CMSSignedData newSignedData = CMSSignedData.replaceSigners(signedData, newSignerStore);
The createTSToken code:
public Attribute createTSToken(byte[] data) throws NoSuchProviderException, NoSuchAlgorithmException, IOException {
// Generate timestamp
MessageDigest digest = MessageDigest.getInstance("SHA1", "BC");
TimeStampResponse response = timestampData(digest.digest(data));
TimeStampToken timestampToken = response.getTimeStampToken();
// Create timestamp attribute
Attribute a = new Attribute(PKCSObjectIdentifiers.id_aa_signatureTimeStampToken, new DERSet(ASN1Primitive.fromByteArray(timestampToken.getEncoded())));
return a;
}
timestampData:
TimeStampRequestGenerator reqgen = new TimeStampRequestGenerator();
TimeStampRequest req = reqgen.generate(TSPAlgorithms.SHA1, data);
byte request[] = req.getEncoded();
URL url = new URL("http://time.certum.pl");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setDoOutput(true);
con.setDoInput(true);
con.setRequestMethod("POST");
con.setRequestProperty("Content-type", "application/timestamp-query");
con.setRequestProperty("Content-length", String.valueOf(request.length));
OutputStream out = con.getOutputStream();
out.write(request);
out.flush();
if (con.getResponseCode() != HttpURLConnection.HTTP_OK) {
throw new IOException("Received HTTP error: " + con.getResponseCode() + " - " + con.getResponseMessage());
}
InputStream in = con.getInputStream();
TimeStampResp resp = TimeStampResp.getInstance(new ASN1InputStream(in).readObject());
response = new TimeStampResponse(resp);
response.validate(req);
if(response.getStatus() != 0) {
System.out.println(response.getStatusString());
return null;
}
return response;
Thanks for your help!
Example files:
Signed PDF with LTV - edited
timestampDatamethod? Can you furthermore provide a sample PDF signed and timestamped by your code? – Festival