问如何使用pdfbox和TimeStampToken添加时间戳

EN

/**
 * SignatureInterface implementation.
 *
 * This method will be called from inside of the pdfbox and create the PKCS #7 signature.
 * The given InputStream contains the bytes that are given by the byte range.
 *
 * This method is for internal use only.
 *
 * Use your favorite cryptographic library to implement PKCS #7 signature creation.
 */
@Override
public byte[] sign(InputStream content) throws IOException
{
    //TODO this method should be private
    try
    {
        List<Certificate> certList = new ArrayList<Certificate>();
        certList.add(certificate);
        Store certs = new JcaCertStore(certList);
        CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
        org.bouncycastle.asn1.x509.Certificate cert = org.bouncycastle.asn1.x509.Certificate.getInstance(ASN1Primitive.fromByteArray(certificate.getEncoded()));
        ContentSigner sha1Signer = new JcaContentSignerBuilder("SHA256WithRSA").build(privateKey);
        gen.addSignerInfoGenerator(new JcaSignerInfoGeneratorBuilder(new JcaDigestCalculatorProviderBuilder().build()).build(sha1Signer, new X509CertificateHolder(cert)));
        gen.addCertificates(certs);
        CMSProcessableInputStream msg = new CMSProcessableInputStream(content);
        CMSSignedData signedData = gen.generate(msg, false);
        if (tsaClient != null)
        {
            signedData = signTimeStamps(signedData);
        }
        return signedData.getEncoded();
    }
    catch (GeneralSecurityException e)
    {
        throw new IOException(e);
    }
    catch (CMSException e)
    {
        throw new IOException(e);
    }
    catch (TSPException e)
    {
        throw new IOException(e);
    }
    catch (OperatorCreationException e)
    {
        throw new IOException(e);
    }
}

/**
 * Sign pdf file and create new file that ends with "_signed.pdf".
 *
 * @param inputFile The source pdf document file.
 * @param signedFile The file to be signed.
 * @param tsaClient optional TSA client
 * @param signatureFieldName optional name of an existing (unsigned) signature field
 * @throws IOException
 */
public void signPDF(File inputFile, File signedFile, TSAClient tsaClient, String signatureFieldName) throws IOException
{
    [...]

    PDSignature signature;

    // sign a PDF with an existing empty signature, as created by the CreateEmptySignatureForm example. 
    signature = findExistingSignature(doc, signatureFieldName);

    if (signature == null)
    {
        // create signature dictionary
        signature = new PDSignature();
    }

    // default filter
    signature.setFilter(PDSignature.FILTER_ADOBE_PPKLITE);

    // subfilter for basic and PAdES Part 2 signatures
    signature.setSubFilter(PDSignature.SUBFILTER_ADBE_PKCS7_DETACHED);

    [...]
}

    signature.setSubFilter(PDSignature.SUBFILTER_ADBE_PKCS7_DETACHED);

    signature.setSubFilter(new COSName("ETSI.RFC3161"));

    signature.setType(new COSName("DocTimeStamp"));