Bouncy Castle 使用 C# 签名并验证 SHA256 证书

Question

我通过大量示例了解人们如何使用 Bouncy Castle 动态生成 RSA 密钥对，然后在一个代码块中进行签名和验证。这些答案很棒，真的帮助我快速提升！

也就是说，我需要创建一个客户端，它可以通过 WCF JSON 调用一个公钥，以便稍后用于签名验证，我似乎无法让它工作。首先是我用来生成证书的代码：

    public System.Security.Cryptography.X509Certificates.X509Certificate2 LoadCertificate()
    {
        System.Security.Cryptography.X509Certificates.X509Certificate2 returnX509 = null;
        //X509Certificate returnCert = null;

        try
        {
            returnX509 = new System.Security.Cryptography.X509Certificates.X509Certificate2(CertificateName, CertificatePassword);
            //returnCert = DotNetUtilities.FromX509Certificate(returnX509);
        }
        catch
        {
            Console.WriteLine("Failed to obtain cert - trying to make one now.");

            try
            {
                Guid nameGuid = Guid.NewGuid();
                AsymmetricCipherKeyPair kp;
                var x509 = GenerateCertificate("CN=Server-CertA-" + nameGuid.ToString(), out kp);
                SaveCertificateToFile(x509, kp, CertificateName, CertificateAlias, CertificatePassword);
                returnX509 = new System.Security.Cryptography.X509Certificates.X509Certificate2(CertificateName, CertificatePassword);
                //returnCert = DotNetUtilities.FromX509Certificate(returnX509);
                Console.WriteLine("Successfully wrote and retrieved cert!");
            }
            catch (Exception exc)
            {
                Console.WriteLine("Failed to create cert - exception was: " + exc.ToString());
            }
        }

        return returnX509;
    }

完成后，我使用以下代码签署消息：

    public string SignData(string Message, string PrivateKey)
    {
        try
        {
            byte[] orgBytes = UnicodeEncoding.ASCII.GetBytes(Message);
            byte[] privateKey = UnicodeEncoding.ASCII.GetBytes(PrivateKey);

            string curveName = "P-521";
            X9ECParameters ecP = NistNamedCurves.GetByName(curveName);
            ECDomainParameters ecSpec = new ECDomainParameters(ecP.Curve, ecP.G, ecP.N, ecP.H, ecP.GetSeed());

            ISigner signer = SignerUtilities.GetSigner("SHA-256withECDSA");
            BigInteger biPrivateKey = new BigInteger(privateKey);
            ECPrivateKeyParameters keyParameters = new ECPrivateKeyParameters(biPrivateKey, ecSpec);

            signer.Init(true, keyParameters);
            signer.BlockUpdate(orgBytes, 0, orgBytes.Length);

            byte[] data = signer.GenerateSignature();
            //Base64 Encode
            byte[] encodedBytes;
            using (MemoryStream encStream = new MemoryStream())
            {
                base64.Encode(orgBytes, 0, orgBytes.Length, encStream);
                encodedBytes = encStream.ToArray();
            }

            if (encodedBytes.Length > 0)
                return UnicodeEncoding.ASCII.GetString(encodedBytes);
            else
                return "";
        }
        catch (Exception exc)
        {
            Console.WriteLine("Signing Failed: " + exc.ToString());
            return "";
        }
    }

最后，我尝试验证：

    public bool VerifySignature(string PublicKey, string Signature, string Message)
    {
        try
        {
            AsymmetricKeyParameter pubKey = new AsymmetricKeyParameter(false);

            var publicKey = PublicKeyFactory.CreateKey(Convert.FromBase64String(PublicKey));
            ISigner signer = SignerUtilities.GetSigner("SHA-256withECDSA");
            byte[] orgBytes = UnicodeEncoding.ASCII.GetBytes(Message);

            signer.Init(false, publicKey);
            signer.BlockUpdate(orgBytes, 0, orgBytes.Length);

            //Base64 Decode
            byte[] encodeBytes = UnicodeEncoding.ASCII.GetBytes(Signature);
            byte[] decodeBytes;
            using (MemoryStream decStream = new MemoryStream())
            {
                base64.Decode(encodeBytes, 0, encodeBytes.Length, decStream);
                decodeBytes = decStream.ToArray();
            }

            return signer.VerifySignature(decodeBytes);
        }
        catch (Exception exc)
        {
            Console.WriteLine("Verification failed with the error: " + exc.ToString());
            return false;
        } 
    }

这是我的测试应用：

        Console.WriteLine("Attempting to load cert...");
        System.Security.Cryptography.X509Certificates.X509Certificate2 thisCert = LoadCertificate();
        if (thisCert != null)
        {
            Console.WriteLine(thisCert.IssuerName.Name);
            Console.WriteLine("Signing the text - Mary had a nuclear bomb");
            string signature = SignData("Mary had a nuclear bomb", thisCert.PublicKey.Key.ToXmlString(true));

            Console.WriteLine("Signature: " + signature);

            Console.WriteLine("Verifying Signature");

            if (VerifySignature(thisCert.PublicKey.Key.ToXmlString(false), signature, "Mary had a nuclear bomb."))
                Console.WriteLine("Valid Signature!");
            else
                Console.WriteLine("Signature NOT valid!");

        }

当我尝试运行测试应用程序时，我收到错误“密钥在指定状态下无效”。上线：

    string signature = SignData("Mary had a nuclear bomb", thisCert.PublicKey.Key.ToXmlString(true));

我尝试用“PrivateKey”替换“PublicKey.Key”，但这并没有什么不同。我也尝试使用 BounceyCastle X509Certificate 但我不知道如何提取密钥。有什么想法吗？

谢谢！

更新：我确实弄清楚了如何仅使用 .NET 进行签名和验证，但这对我来说并不是很有用，因为我需要跨平台，事实上，我们的主要客户端应用程序是用 Java 编写的。有人知道相当于下面代码的充气城堡吗？

    public string SignDataAsXml(string Message, X509Certificate2 ThisCert)
    {
        XmlDocument doc = new XmlDocument();
        doc.PreserveWhitespace = false;
        doc.LoadXml("<core>" + Message + "</core>");

        // Create a SignedXml object.
        SignedXml signedXml = new SignedXml(doc);

        // Add the key to the SignedXml document. 
        signedXml.SigningKey = ThisCert.PrivateKey;

        // Create a reference to be signed.
        Reference reference = new Reference();
        reference.Uri = "";

        // Add an enveloped transformation to the reference.
        XmlDsigEnvelopedSignatureTransform env = new XmlDsigEnvelopedSignatureTransform();
        reference.AddTransform(env);

        // Add the reference to the SignedXml object.
        signedXml.AddReference(reference);

        // Create a new KeyInfo object.
        KeyInfo keyInfo = new KeyInfo();

        // Load the certificate into a KeyInfoX509Data object 
        // and add it to the KeyInfo object.
        keyInfo.AddClause(new KeyInfoX509Data(ThisCert));

        // Add the KeyInfo object to the SignedXml object.
        signedXml.KeyInfo = keyInfo;

        // Compute the signature.
        signedXml.ComputeSignature();

        // Get the XML representation of the signature and save 
        // it to an XmlElement object.
        XmlElement xmlDigitalSignature = signedXml.GetXml();

        // Append the element to the XML document.
        doc.DocumentElement.AppendChild(doc.ImportNode(xmlDigitalSignature, true));


        if (doc.FirstChild is XmlDeclaration)
        {
            doc.RemoveChild(doc.FirstChild);
        }

        using (var stringWriter = new StringWriter())
        {
            using (var xmlTextWriter = XmlWriter.Create(stringWriter))
            {
                doc.WriteTo(xmlTextWriter);
                xmlTextWriter.Flush();
                return stringWriter.GetStringBuilder().ToString();
            }
        }
    }

    public bool VerifyXmlSignature(string XmlMessage, X509Certificate2 ThisCert)
    {
        // Create a new XML document.
        XmlDocument xmlDocument = new XmlDocument();

        // Load the passed XML file into the document. 
        xmlDocument.LoadXml(XmlMessage);

        // Create a new SignedXml object and pass it the XML document class.
        SignedXml signedXml = new SignedXml(xmlDocument);

        // Find the "Signature" node and create a new XmlNodeList object.
        XmlNodeList nodeList = xmlDocument.GetElementsByTagName("Signature");

        // Load the signature node.
        signedXml.LoadXml((XmlElement)nodeList[0]);

        // Check the signature and return the result. 
        return signedXml.CheckSignature(ThisCert, true);
    }

Answer 1

Bouncy Castle 根本不支持 XML 格式。除非您的用例严格要求它，否则您会发现仅使用 Base64 编码会更容易，证书 (X.509) 和私钥 (PKCS#8) 以 PEM 格式存储。这些都是字符串格式，所以应该可以直接和 JSON 一起使用。

代码示例中还有其他问题：签名应该使用私钥，签名不应该被视为 ASCII 字符串，可能您的消息实际上是 UTF8。我希望内部签名/验证例程可能看起来像这样：

    public string SignData(string msg, ECPrivateKeyParameters privKey)
    {
        try
        {
            byte[] msgBytes = Encoding.UTF8.GetBytes(msg);

            ISigner signer = SignerUtilities.GetSigner("SHA-256withECDSA");
            signer.Init(true, privKey);
            signer.BlockUpdate(msgBytes, 0, msgBytes.Length);
            byte[] sigBytes = signer.GenerateSignature();

            return Convert.ToBase64String(sigBytes);
        }
        catch (Exception exc)
        {
            Console.WriteLine("Signing Failed: " + exc.ToString());
            return null;
        }
    }

    public bool VerifySignature(ECPublicKeyParameters pubKey, string signature, string msg)
    {
        try
        {
            byte[] msgBytes = Encoding.UTF8.GetBytes(msg);
            byte[] sigBytes = Convert.FromBase64String(signature);

            ISigner signer = SignerUtilities.GetSigner("SHA-256withECDSA");
            signer.Init(false, pubKey);
            signer.BlockUpdate(msgBytes, 0, msgBytes.Length);
            return signer.VerifySignature(sigBytes);
        }
        catch (Exception exc)
        {
            Console.WriteLine("Verification failed with the error: " + exc.ToString());
            return false;
        }
    }

另一个问题是我认为 .NET 直到 .NET 3.5 才获得 ECDSA 支持，无论如何 .NET 1.1 中没有 ECDsa 类（这是 BC 即将发布的 1.8 版本的目标 - 我们将“现代化" 之后），因此 DotNetUtilities 不支持 ECDSA。但是，我们可以导出到 PKCS#12 并导入到 BC。一个示例程序：

    public void Program()
    {
        Console.WriteLine("Attempting to load cert...");
        System.Security.Cryptography.X509Certificates.X509Certificate2 thisCert = LoadCertificate();

        Console.WriteLine(thisCert.IssuerName.Name);
        Console.WriteLine("Signing the text - Mary had a nuclear bomb");

        byte[] pkcs12Bytes = thisCert.Export(X509ContentType.Pkcs12, "dummy");
        Pkcs12Store pkcs12 = new Pkcs12StoreBuilder().Build();
        pkcs12.Load(new MemoryStream(pkcs12Bytes, false), "dummy".ToCharArray());

        ECPrivateKeyParameters privKey = null;
        foreach (string alias in pkcs12.Aliases)
        {
            if (pkcs12.IsKeyEntry(alias))
            {
                privKey = (ECPrivateKeyParameters)pkcs12.GetKey(alias).Key;
                break;
            }
        }

        string signature = SignData("Mary had a nuclear bomb", privKey);

        Console.WriteLine("Signature: " + signature);

        Console.WriteLine("Verifying Signature");

        var bcCert = DotNetUtilities.FromX509Certificate(thisCert);
        if (VerifySignature((ECPublicKeyParameters)bcCert.GetPublicKey(), signature, "Mary had a nuclear bomb."))
            Console.WriteLine("Valid Signature!");
        else
            Console.WriteLine("Signature NOT valid!");
    }

我还没有真正测试过上面的任何代码，但它应该会给你一些继续的东西。请注意，BC 也有密钥和证书生成器，因此您可以选择将 BC 用于所有内容（XML 除外！），并仅在必要时向/从 .NET 土地导出/导入。

Answer 2

感谢 Petters 的回答，我想添加代码以使用 RSA 算法验证签名。

public bool VerifySignature(AsymmetricKeyParameter pubKey, string signature, string msg)
{
    try
    {
        byte[] msgBytes = Encoding.UTF8.GetBytes(msg);
        byte[] sigBytes = Convert.FromBase64String(signature);

        ISigner signer = SignerUtilities.GetSigner("SHA-256withRSA");
        signer.Init(false, pubKey);
        signer.BlockUpdate(msgBytes, 0, msgBytes.Length);
        return signer.VerifySignature(sigBytes);
    }
    catch (Exception exc)
    {
        Console.WriteLine("Verification failed with the error: " + exc.ToString());
        return false;
    }
}