Question

我想使用pdf摘要签名pdf。我使用以下代码创建了哈希，

byte[] buffer = new byte[1024];
int numOfBytesRead =0;
MessageDigest md = null;
md = MessageDigest.getInstance("SHA256","BC");
while((numOfBytesRead = content.read(buffer)) != -1 ){
     md.update(buffer, 0, numOfBytesRead);
}
byte[] digest = md.digest();

最后，我需要将此签名附加到pdf上。我找到了一种解决方案Create pkcs7 signature from file digest，但是链接中使用的算法是 SHA256withRSA 。我的私钥使用 EC 算法生成，我需要使用 SHA256withECDSA 。是否可以使用 SHA256withECDSA 对哈希进行签名并将签名附加到使用 PDFBox ExternalSigning 界面创建pdf。

Answer 1

在许多情况下，Adobe称签署人的证书无效，即使该证书显然有效；特别是在手头的情况下：

密钥用法或扩展密钥用法值不合适
PAdES签名缺少ESS signing-certificate-v2属性

密钥用法或扩展密钥用法值不合适

这是基于OP最初发布为an answer

的信息

我仍然尝试在下面的代码中pdf指出签名无效。您能检查一下代码吗？

[...]

我附上了pdf。 Pdf file created

确实，Adobe Reader说签名无效，但请仔细观察：

上面写着“自从应用此签名以来，文档没有被修改”-这表示该签名在数学上是正确的！

问题在于“签名者的证书无效”，在深入研究签名属性对话框时可以看到其原因：

因此，问题在于您的签名者证书使用无效。

这是由于突出显示了属性，而“密钥用法” “数字签名” 正常时，“扩展密钥用法” 1.3.6.1.5.5.8.2.2 （ IPSEC保护的OID不是！

根据Adobe Digital Signatures Guide for IT，Adobe Acrobat仅接受

以下一个或多个主要用法值（如果有）
- 不可否认
- signTransaction（仅11.0.09）
- digitalSignature（11.0.10及更高版本）
和以下一个或多个扩展密钥用法值（如果有）
- 电子邮件保护
- codeSigning
- anyExtendedKeyUsage
- 1.2.840.113583.1.1.5（Adobe Authentic Documents Trust）

由于其 IPSEC保护扩展密钥用法值，因此，您的证书对于签署PDF文档无效。

这可能仅是旧版ISO 32000-1签名中的问题，可能不是PAdES签名中的问题。

PAdES签名缺少ESS signing-certificate-v2属性

这是基于OP最初发布为an answer

的信息

我已经创建了2个pdf文件，使用以下代码的pdf内容摘要对PDFA进行了签名，

[...]

PDFA

PDFB是使用相同的私钥和证书创建的，但我不是使用摘要而是直接使用pdf文档内容，这给了我有效的签名pdf，下面的PDFB代码

[...]

PDFB

我认为PDFA的签名部分缺少一些我无法弄清的东西。

这里的主要区别不是您自己显式计算哈希还是允许隐式计算哈希，主要区别在于PDFB中的签名包含ESS signing-certificate-v2属性，而PDFA中的签名不包含。此属性是在

之间生成的

//PAdES - PDF Advanced Electronic Signature

和

//PAdES-end

正如评论已经暗示的那样，这仅对于PAdES签名是必需的，而对于传统的ISO 32000-1签名则不是必需的。 The answer the OP took his original code from是指在OP创建PAdES签名时创建旧版ISO 32000-1签名（因此可以正常工作）。

PAdES规范ETSI EN 319 142-1需要ESS签名证书属性的存在：

e）生成器应根据ETSI EN 319 122-1，根据哈希函数使用签名证书或signing-certificate v2属性。

（ETSI EN 319 142-1，第6.3节PAdES基线签名）

它引用了CAdES规范ETSI EN 319 122-1，

h）SPO的要求：ESS signing-certificate。如果使用SHA-1哈希算法，则应使用ESS signing-certificate属性。

i）SPO的要求：ESS signing-certificate-v2。当使用除SHA-1以外的其他哈希算法时，应使用ESS signing-certificate-v2属性。

（ETSI EN 319 122-1，第6.3节组件和服务要求）

Answer 2

我尝试了以下代码，但pdf仍然显示签名无效。您能检查一下代码吗，

System.out.println("Hash Signing started");
    List<Certificate> certList = getFormatCertificate(strCertificate);
    PrivateKey privateKey;
    CMSSignedData s = null;
    Security.addProvider(new BouncyCastleProvider());
    byte[] signature = null;
    try {
        privateKey = loadPrivateKey(strPrivatekey);
        byte[] buffer = new byte[1024];
        int numOfBytesRead =0;
        MessageDigest md = null;
        md = MessageDigest.getInstance("SHA256","BC");
        while((numOfBytesRead = content.read(buffer)) != -1 ){
            md.update(buffer, 0, numOfBytesRead);
        }
        byte[] digest = md.digest();

        // Separate signature container creation step
        JcaCertStore certs = new JcaCertStore(certList);

        CMSSignedDataGenerator gen = new CMSSignedDataGenerator();

        Attribute attr = new Attribute(CMSAttributes.messageDigest,
                new DERSet(new DEROctetString(digest)));

        ASN1EncodableVector v = new ASN1EncodableVector();

        v.add(attr);

        SignerInfoGeneratorBuilder builder = new SignerInfoGeneratorBuilder(new BcDigestCalculatorProvider())
                .setSignedAttributeGenerator(new DefaultSignedAttributeTableGenerator(new AttributeTable(v)));

        //AlgorithmIdentifier sha256withECDSA = new DefaultSignatureAlgorithmIdentifierFinder().find(signerAlgorithm);

        CertificateFactory certFactory = CertificateFactory.getInstance("X.509");
        InputStream in = new ByteArrayInputStream(certList.get(certList.size()-1).getEncoded());
        X509Certificate cert = (X509Certificate) certFactory.generateCertificate(in);

        gen.addSignerInfoGenerator(builder.build(
                new JcaContentSignerBuilder(signerAlgorithm).build(privateKey),
                new JcaX509CertificateHolder(cert)));
        //DErse
//      gen.addSignerInfoGenerator(builder.build(
//              new JcaContentSignerBuilder(sha256withRSA,
//                      new DefaultDigestAlgorithmIdentifierFinder().find(sha256withRSA))
//                              .build(PrivateKeyFactory.createKey(privateKey.getEncoded())),
//              new JcaX509CertificateHolder(cert)));

        gen.addCertificates(certs);

        s = gen.generate(new CMSAbsentContent(), false);
        System.out.println("Hash sign completed");
        signature = s.getEncoded();// ConstructEcdsaSigValue(s.getEncoded());
    } catch (GeneralSecurityException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("GeneralSecurityException ::"+e.toString());
    } catch (OperatorCreationException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("OperatorCreationException ::"+e.toString());
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("IOException ::"+e.toString());
    } catch (CMSException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("CMSException ::"+e.toString());
    }finally{
        return signature;
    }

我附上了pdf。 Pdf file created

@ Mkl / Tilman：我创建了2个pdf文件，使用以下代码的pdf内容摘要对PDFA进行了签名，

System.out.println("Hash Signing started");
    List<Certificate> certList = getFormatCertificate(strCertificate);
    PrivateKey privateKey;
    CMSSignedData s = null;
    Security.addProvider(new BouncyCastleProvider());
    byte[] signature = null;
    try {
        privateKey = loadPrivateKey(strPrivatekey);

        /*byte[] buffer = new byte[1024];
        int numOfBytesRead =0;
        MessageDigest md = null;
        //md = MessageDigest.getInstance("SHA256","BC");
        md = MessageDigest.getInstance("SHA-256");
        while((numOfBytesRead = content.read(buffer)) != -1 ){
            md.update(buffer, 0, numOfBytesRead);
        }
        byte[] digest = md.digest();*/
        MessageDigest md = MessageDigest.getInstance("SHA256", "BC");
        byte[] digest = md.digest(IOUtils.toByteArray(content));

        // Separate signature container creation step
        JcaCertStore certs = new JcaCertStore(certList);

        CMSSignedDataGenerator gen = new CMSSignedDataGenerator();

        Attribute attr = new Attribute(CMSAttributes.messageDigest,
                new DERSet(new DEROctetString(digest)));

        ASN1EncodableVector v = new ASN1EncodableVector();

        v.add(attr);

        SignerInfoGeneratorBuilder builder = new SignerInfoGeneratorBuilder(new BcDigestCalculatorProvider())
                .setSignedAttributeGenerator(new DefaultSignedAttributeTableGenerator(new AttributeTable(v)));

        //AlgorithmIdentifier sha256withECDSA = new DefaultSignatureAlgorithmIdentifierFinder().find(signerAlgorithm);

        CertificateFactory certFactory = CertificateFactory.getInstance("X.509");
        InputStream in = new ByteArrayInputStream(certList.get(certList.size()-1).getEncoded());
        X509Certificate cert = (X509Certificate) certFactory.generateCertificate(in);

        gen.addSignerInfoGenerator(builder.build(
                new JcaContentSignerBuilder(signerAlgorithm).build(privateKey),
                new JcaX509CertificateHolder(cert)));
        //DErse
//      gen.addSignerInfoGenerator(builder.build(
//              new JcaContentSignerBuilder(sha256withRSA,
//                      new DefaultDigestAlgorithmIdentifierFinder().find(sha256withRSA))
//                              .build(PrivateKeyFactory.createKey(privateKey.getEncoded())),
//              new JcaX509CertificateHolder(cert)));

        gen.addCertificates(certs);

        s = gen.generate(new CMSAbsentContent(), false);
        System.out.println("Hash sign completed");
        signature = s.getEncoded();// ConstructEcdsaSigValue(s.getEncoded());
    } catch (GeneralSecurityException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("GeneralSecurityException ::"+e.toString());
    } catch (OperatorCreationException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("OperatorCreationException ::"+e.toString());
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("IOException ::"+e.toString());
    } catch (CMSException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("CMSException ::"+e.toString());
    }finally{
        return signature;
    }

PDFA

PDFB是使用相同的私钥和证书创建的，但我没有使用摘要，而是直接使用pdf文档内容，这给了我有效的签名pdf，下面的PDFB代码，

SignatureInterface signatureInterface = new SignatureInterface() {
                    @SuppressWarnings("rawtypes")
                    @Override
                    public byte[] sign(InputStream content) throws IOException {
                        try {
                            byte[] certificateByte = null;

                            Store certs = new JcaCertStore(certificates);

                            //PAdES - PDF Advanced Electronic Signature
                            //ESS - Enhanced Security Services
                            //ASN1 - Abstract Syntax Notation One-standard interface description language for defining data structures that can be serialized and deserialized in a cross-platform way
                            // Generating certificate hash
                            MessageDigest md = MessageDigest.getInstance("SHA-256");
                            md.update(certificates.get(certificates.size()-1).getEncoded());
                            byte[] certHash = md.digest();
                            // Generating certificate hash ends
                            System.out.println("Cert hash generated");
                            //ESSCertIDv2 identifies the certificate from the hash
                            ESSCertIDv2 essCert1 =
                                    new ESSCertIDv2(new AlgorithmIdentifier(NISTObjectIdentifiers.id_sha256), certHash);
                            ESSCertIDv2[] essCert1Arr =
                                    {
                                            essCert1
                                    };
                            SigningCertificateV2 scv2 = new SigningCertificateV2(essCert1Arr);
                            Attribute certHAttribute =
                                    new Attribute(PKCSObjectIdentifiers.id_aa_signingCertificateV2, new DERSet(scv2));
                            ASN1EncodableVector v = new ASN1EncodableVector();
                            v.add(certHAttribute);

                            AttributeTable at = new AttributeTable(v);

                            //Create a standard attribute table from the passed in parameters - certhash
                            CMSAttributeTableGenerator attrGen = new DefaultSignedAttributeTableGenerator(at){
                                protected Hashtable createStandardAttributeTable(Map parameters)
                                {
                                    Hashtable result = super.createStandardAttributeTable(parameters);
                                    result.remove(CMSAttributes.signingTime);
                                    return result;
                                }
                            };
                            //PAdES-end
                            System.out.println("CMSAttributeTableGenerator generated");
                            SignerInfoGeneratorBuilder genBuild =
                                    new SignerInfoGeneratorBuilder(new BcDigestCalculatorProvider());
                            genBuild.setSignedAttributeGenerator(attrGen);
                            //Get single certificate
                            org.spongycastle.asn1.x509.Certificate certas1 = org.spongycastle.asn1.x509.Certificate.getInstance(ASN1Primitive.fromByteArray(certificates.get(certificates.size()-1).getEncoded()));
                            // ContentSigner interface creates SHA256withECDSA signer using PvtKey
                            ContentSigner sha1Signer = new JcaContentSignerBuilder(signerAlgorithm).build(privateKey);
                            //Creates SignerInfoGenerator using X.509 cert and ContentSigner
                            SignerInfoGenerator sifGen = genBuild.build(sha1Signer, new X509CertificateHolder(certas1));

                            // CMSSignedDataGenerator generates a pkcs7-signature message 
                            CMSSignedDataGenerator gen = new CMSSignedDataGenerator();

                            gen.addCertificates(certs);
                            gen.addSignerInfoGenerator(sifGen);
                            //Creates CMS message from PDF
                            CMSProcessableInputStream msg = new CMSProcessableInputStream(content);
                            //Generate a CMS Signed Data object which can be carrying a detached CMS signature
                            //msg - content to be signed
                            CMSSignedData signedData = gen.generate(msg, false);
                            System.out.println("CMSSignedData is done");
                            return signedData.getEncoded();
                        } catch (GeneralSecurityException e) {
                            throw new IOException(e);
                        } catch (CMSException e) {
                            throw new IOException(e);
                        } catch (OperatorCreationException e) {
                            throw new IOException(e);
                        }
                }

            };
            System.out.println("CMSSignedData is done2");
            PDDocument pdDocument =  PDDocument.load(inputfile);

            System.out.println("pdDocument loaded");
            pdDocument.addSignature(signature, signatureInterface);

PDFB

我认为PDFA的签名部分缺少某些内容，我无法弄清。

如何从摘要中生成PKCS＃7签名？

2 个答案:

密钥用法或扩展密钥用法值不合适

PAdES签名缺少ESS signing-certificate-v2属性