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 文件中创建分离签名。数据（哈希）已在使用私钥的不同设备上预先签名。我想创建一个包含签名数据的 PKCS7 以及带有公钥的证书。如果不提供私钥并让图书馆签署数据，我似乎无法创建带有充气城堡的 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

我设法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”由硬件设备执行，它可能还包含“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));

你也应该删除

signatureGenerator.setDirectSignature(true)

一个完整的例子可以在这里找到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，而这篇文章提供了一个重要的线索，我认为我应该在一篇文章中补充我仍然错过的信息。谢谢。