带有多个签名的iText7 PDF

Question

我正在将代码从iText5迁移到iText7，目前我正在努力将一个签名添加到已经包含另一个签名的PDF中。这些签名是用我们的国民身份证（公民卡）进行的。

在iText5中，我使用了PdfStamper，但它在Itext7中丢失了...

这是我目前所掌握的：

package cartaocidadao;

import java.io.FileOutputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.Security;
import java.security.cert.Certificate;
import javax.swing.JOptionPane;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.poreid.config.POReIDConfig;
import org.poreid.crypto.POReIDProvider;
import com.itextpdf.signatures.OcspClientBouncyCastle;
import com.itextpdf.signatures.TSAClientBouncyCastle;
import java.io.IOException;
import java.util.Collection;

import com.itextpdf.kernel.geom.Rectangle;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.signatures.BouncyCastleDigest;
import com.itextpdf.signatures.ICrlClient;
import com.itextpdf.signatures.DigestAlgorithms;
import com.itextpdf.signatures.IExternalDigest;
import com.itextpdf.signatures.IExternalSignature;
import com.itextpdf.signatures.IOcspClient;
import com.itextpdf.signatures.PdfSignatureAppearance;
import com.itextpdf.signatures.PdfSigner;
import com.itextpdf.signatures.PrivateKeySignature;
import com.itextpdf.signatures.ITSAClient;
import com.itextpdf.signatures.OCSPVerifier;
import java.security.GeneralSecurityException;
import static javax.swing.JOptionPane.ERROR_MESSAGE;

/**
 *
 * @author i.lourenco
 */
public class Signature {

    /**
     *  Signs the PDF with the Citizen Card Certificate
     * @param src Source file
     * @param dest Destination file
     * @return TRUE if the PDF was signed successfully
     */
    protected static boolean signPDF(String src, String dest) {

        try {

            Security.addProvider(new POReIDProvider());

            BouncyCastleProvider provider = new BouncyCastleProvider();
            Security.addProvider(provider);

            KeyStore ks = KeyStore.getInstance(POReIDConfig.POREID);
            ks.load(null);

            PrivateKey pk = (PrivateKey) ks.getKey(POReIDConfig.ASSINATURA, null);

            Certificate[] chain = ks.getCertificateChain(POReIDConfig.ASSINATURA);

            OCSPVerifier ocspVerifier = new OCSPVerifier(null, null);

            IOcspClient ocspClient = new OcspClientBouncyCastle(ocspVerifier);

            ITSAClient tsaClient = new TSAClientBouncyCastle("http://ts.cartaodecidadao.pt/tsa/server", "", "");

            sign(src, dest, chain, pk, DigestAlgorithms.SHA256, POReIDConfig.POREID, PdfSigner.CryptoStandard.CMS, "", "", null, ocspClient, tsaClient, 0);
        } catch (Exception e) {
            JOptionPane.showMessageDialog(null, e.getMessage(), "Erro", ERROR_MESSAGE);
        }

        return true;
    }

    /**
     * Applies the certificate, timestamp and revocation list to a PDF
     * @param src Original PDF document
     * @param dest Signed PDF document
     * @param chain List of certificates
     * @param pk Private key
     * @param digestAlgorithm Encryption algorithm
     * @param provider Citizen Card provider
     * @param subfilter CMS
     * @param reason Reason for signature
     * @param location Location
     * @param crlList Revocation list
     * @param ocspClient Online Certification Status
     * @param tsaClient Timestamp server
     * @param estimatedSize
     * @throws IOException
     * @throws GeneralSecurityException 
     */
    private static void sign(String src, String dest, Certificate[] chain, PrivateKey pk, String digestAlgorithm, 
            String provider, PdfSigner.CryptoStandard subfilter, String reason, String location, Collection<ICrlClient> crlList, 
            IOcspClient ocspClient, ITSAClient tsaClient, int estimatedSize) throws IOException, GeneralSecurityException {

        PdfReader reader = new PdfReader(src);

        PdfSigner signer = new PdfSigner(reader, new FileOutputStream(dest), false);

        PdfSignatureAppearance appearance = signer.getSignatureAppearance()
                .setReason(reason)
                .setLocation(location)
                .setReuseAppearance(false);
        Rectangle rect = new Rectangle(36, 648, 200, 100);
        appearance.setPageRect(rect).setPageNumber(1);

        signer.getNewSigFieldName();

        IExternalSignature pks = new PrivateKeySignature(pk, digestAlgorithm, provider);
        IExternalDigest digest = new BouncyCastleDigest();

        signer.signDetached(digest, pks, chain, crlList, ocspClient, tsaClient, estimatedSize, subfilter);
    }


}

POReID（https://github.com/POReID/POReID）是用于与智能卡交互的库。

当第一次签署文件时，它工作得很好。再次对文档签名时，它使第一个签名无效，只有最后一个签名有效。

两个签名

Answer 1

PdfSigner signer = new PdfSigner(reader, new FileOutputStream(dest), false);

PdfSigner signer = new PdfSigner(reader, new FileOutputStream(dest), true);

构造函数中的第三个参数确定是否在追加模式下使用签名者。