使用充气城堡创建带有预签名数据的PKCS7

Question

我想使用PKCS7容器在PDF文件中创建分离的签名。 数据（哈希）已预先使用私钥在其他设备上签名。 我想创建一个包含签名数据以及带有公钥的证书的PKCS7。 如果没有提供私钥并使库对数据进行签名，我似乎无法创建带有弹力城堡的PKCS7。 这似乎不起作用：

        InputStream inStream = new FileInputStream("1_public.pem");
        BufferedInputStream bis = new BufferedInputStream( inStream );

        CertificateFactory cf = CertificateFactory.getInstance("X.509");

        List<Certificate> certList = new ArrayList<Certificate>();
        Certificate certificate = cf.generateCertificate(bis);
        certList.add(certificate);
        Store certs = new JcaCertStore(certList);

        CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
        gen.addCertificates( certs );
        CMSProcessableInputStream msg = new CMSProcessableInputStream( new ByteArrayInputStream( "signedhash".getBytes() ) );

        CMSSignedData signedData = gen.generate(msg, false);
        byte[] pkcs7 = signedData.getEncoded() ) );

Answer 1

我通过提供一个不签名的ContentSigner来做到这一点，实际上非常简单：

        InputStream inStream = new FileInputStream("1_public.pem");
        BufferedInputStream bis = new BufferedInputStream( inStream );

        CertificateFactory cf = CertificateFactory.getInstance("X.509");

        List<Certificate> certList = new ArrayList<Certificate>();
        Certificate certificate = cf.generateCertificate(bis);
        certList.add(certificate);
        Store certs = new JcaCertStore(certList);
        CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
        gen.addCertificates( certs );

        final byte[] signedHash = "signedhash".getBytes();

        ContentSigner nonSigner = new ContentSigner() {

            @Override
            public byte[] getSignature() {
                return signedHash;
            }

            @Override
            public OutputStream getOutputStream() {
                return new ByteArrayOutputStream();
            }

            @Override
            public AlgorithmIdentifier getAlgorithmIdentifier() {
                return new DefaultSignatureAlgorithmIdentifierFinder().find( "SHA256WithRSA" );
            }
        };

        org.bouncycastle.asn1.x509.Certificate cert = org.bouncycastle.asn1.x509.Certificate.getInstance(ASN1Primitive.fromByteArray(certificate.getEncoded()));
        JcaSignerInfoGeneratorBuilder sigb = new JcaSignerInfoGeneratorBuilder(new JcaDigestCalculatorProviderBuilder().build());
        sigb.setDirectSignature( true );
        gen.addSignerInfoGenerator(sigb.build(nonSigner, new X509CertificateHolder(cert)));
        CMSProcessableInputStream msg = new CMSProcessableInputStream( new ByteArrayInputStream( "not used".getBytes() ) );

        CMSSignedData signedData = gen.generate(msg, false);
        byte[] pkcs7 = signedData.getEncoded();

Answer 2

如果“外部签名”是由硬件设备执行的，则它也可能包含“签名属性”。 在这种情况下，代码还必须包含：

AttributeTable signedAttributes = signer.getSignedAttributes();
signerInfoBuilder.setSignedAttributeGenerator(new SimpleAttributeTableGenerator(signedAttributes));     
signatureGenerator.addSignerInfoGenerator(signerInfoBuilder.build(nonSigner, signCertificate));

您还应该删除

signatureGenerator.setDirectSignature(true)

有关完整示例，请参见https://www.len.ro/work/attach-payload-into-detached-pkcs7-signature/ 。 由于我花了很多时间寻找解决方案，并且这篇文章提供了重要的线索，我认为我应该补充我仍然在文章中缺少的信息。 谢谢。