我在 .NET Framework 4.5 版中遇到了一个阻止程序来处理带有数字签名的 XML 签名。

我的问题是基于需要使用 RSA SHA-256 算法使用 X.509 证书对单个 XML 元素进行签名。我已经阅读了很多关于这个主题的 .NET 帖子，似乎有一个解决方案最初是在 CLR 安全项目 RSAPKCS1SHA256SignatureDescription.cs 类中开发的。 RSAPKCS1SHA256SignatureDescription 当然已经合并到 .net 运行时中，从 .NET 4.5 开始，现在可以在分布式二进制 System.Deployment.dll 下使用。我已尝试在 .NET 中使用上述解决方案使用 RSA SHA-256 对特定的 XML 元素进行签名，但尚未取得任何成功。

我正在尝试使用 WSSE token 签署符合 Oasis ebms 标准的 SOAP 消息。请注意，该类(class)是为满足 Soap With Attachments (SwA) 和签署个人附件而编写的。 我的代码如下

我的代码如下:

using System;
using System.Collections.Generic;
using System.IO;
using System.IdentityModel.Tokens;
using System.Security;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Security.Cryptography.Xml;
using System.ServiceModel.Channels;
using System.ServiceModel.Security;
using System.Text;
using System.Xml;
using System.Xml.Linq;
using System.Xml.Serialization;
using System.Deployment.Internal.CodeSigning;

namespace TestCSharpX509CertificateRSSHA256
{
    public class SignatureSupportUtility
    {

    private bool IsSignatureContentTransform
    {
        get
        {
          return true;
          //get IsSignatureContentTransform                
        }
    }

       public SignatureSupportUtility()
       {
          Register();
       }


    private static void Register()
    {
        CryptoConfig.AddAlgorithm(typeof(RSAPKCS1SHA256SignatureDescription), "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256");
    }

    private void Sign(Message message, string[] elementIdsToSign, string[] attachmentsToSign, string wssNamespace, X509Certificate2 certificate)
    {
       //Prepare XML to encrypt and sign
       var element = this.PrepareEncyrptSign(message);

            bool signEntireDocument = true;
            string elementToBeSigned = string.Empty;
            var signedMessage = new XmlDocument();
            signedMessage.AppendChild(signedMessage.ImportNode(element, true));

            SignatureType signAs = SignatureType.InternallyDetached;
            signedMessage.PreserveWhitespace = false;

            OverrideSignedXml signedXml = new OverrideSignedXml(signedMessage);
            signedXml.SignedInfo.CanonicalizationMethod = SignedXml.XmlDsigExcC14NTransformUrl;

            if (elementIdsToSign != null && elementIdsToSign.Length > 0)
            {
                bool isContentTransform = this.IsSignatureContentTransform;

                foreach (string s in elementIdsToSign)
                {
                    // Create a reference to be signed.
                    Reference reference = new Reference(string.Format("#{0}", s));
                    reference.AddTransform(new XmlDsigExcC14NTransform());
                    reference.DigestMethod = "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256";


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

                signEntireDocument = false;
            }

            // Reference attachments to sign
            if (attachmentsToSign != null && attachmentsToSign.Length > 0)
            {
                bool isContentTransform = this.IsSignatureContentTransform;

                foreach (string attachmentId in attachmentsToSign)
                {
                    // Create a reference to be signed.
                    Reference reference = new Reference(string.Format("{0}{1}", Constants.CidUriScheme, attachmentId));
                    reference.DigestMethod = "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256";

                    if (isContentTransform)
                    {
                        AttachmentContentSignatureTransform env = new AttachmentContentSignatureTransform();
                        reference.AddTransform(env);
                    }
                    else
                    {
                        AttachmentCompleteSignatureTransform env = new AttachmentCompleteSignatureTransform();
                        reference.AddTransform(env);
                    }

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

                signEntireDocument = false;
            }

            if (signEntireDocument)
            {
                Reference reference = new Reference();
                reference.Uri = "";
                reference.DigestMethod = "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256";

                XmlDsigEnvelopedSignatureTransform env = new XmlDsigEnvelopedSignatureTransform();
                reference.AddTransform(env);
                signedXml.AddReference(reference);
                signAs = SignatureType.Enveloped;
            }

            string x509CertificateReferenceId = string.Format("{0}-{1}", Constants.IdAttributeName, Guid.NewGuid().ToString("N"));
            KeyInfo keyInfo = new KeyInfo();
            keyInfo.AddClause(new KeyInfoX509SecurityTokenReference(string.Format("#{0}", x509CertificateReferenceId), wssNamespace));
            signedXml.KeyInfo = keyInfo;
           signedXml.SignedInfo.SignatureMethod = "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256";

           RSA  key = (RSACryptoServiceProvider)certificate.PrivateKey;
           signedXML.SigningKey = key;
            CidWebRequest.Message = message;

            signedXml.ComputeSignature();
            var xmlSignature = signedXml.GetXml();
            XmlDocument unsignedEnvelopeDoc = new XmlDocument();
            unsignedEnvelopeDoc.LoadXml(message.MessageAsString); }}} 

using System;
using System.Collections.Generic;
using System.IO;
using System.IdentityModel.Tokens;
using System.Security;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Security.Cryptography.Xml;
using System.ServiceModel.Channels;
using System.ServiceModel.Security;
using System.Text;
using System.Xml;
using System.Xml.Linq;
using System.Xml.Serialization;
using System.Deployment.Internal.CodeSigning;


namespace TestCSharpX509CertificateRSSHA256
{
public sealed class OverrideSignedXml : SignedXml
{
    public OverrideSignedXml()
        : base()
    {
    }

    public OverrideSignedXml(XmlDocument doc)
        : base(doc)
    {
    }

    public override XmlElement GetIdElement(XmlDocument document, string idValue)
    {
        XmlElement element = base.GetIdElement(document, idValue);

        if (element == null)
        {
            XmlNamespaceManager nsmgr = new XmlNamespaceManager(document.NameTable);
            nsmgr.AddNamespace("wsu", ="http://docs.oasis-open. org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd");

            element = document.SelectSingleNode("//*[@wsu:Id=\"" + idValue + "\"]", nsmgr) as XmlElement;
        }

        return element;
    }
}

我的 SignatureSupportUtility 类中的 Sign 方法应该足以对单个 XML 元素或整个消息进行签名，但是我一直收到 Cryptography 异常，声称不支持 SHA-256。我认为这个异常不应该是有效的观察 RSAPKCS1SHA256SignatureDescription.cs 已注册。但是，观察到 SignedXML 类不包含 SHA-256 的命名空间，而只包含 SHA-128，我开始怀疑无论是否注册，是否都支持 SHA 256。

有人可以告诉我如何最好地解决我的问题并能够通过 RSA SHA 256 算法使用 X.509 证书签署 XML 吗？

最佳答案

我也在看 Oasis ebms 的东西。

我找不到我从中获取这篇文章的文章，但我使用了 4.5 中的那个类:

public class RsaPkCs1Sha256SignatureDescription : SignatureDescription
{
    public RsaPkCs1Sha256SignatureDescription()
    {
        KeyAlgorithm = "System.Security.Cryptography.RSACryptoServiceProvider";
        DigestAlgorithm = "System.Security.Cryptography.SHA256Managed";
        FormatterAlgorithm = "System.Security.Cryptography.RSAPKCS1SignatureFormatter";
        DeformatterAlgorithm = "System.Security.Cryptography.RSAPKCS1SignatureDeformatter";
    }

    public override AsymmetricSignatureDeformatter CreateDeformatter(AsymmetricAlgorithm key)
    {
        var asymmetricSignatureDeformatter = (AsymmetricSignatureDeformatter) CryptoConfig.CreateFromName(DeformatterAlgorithm);
        asymmetricSignatureDeformatter.SetKey(key);
        asymmetricSignatureDeformatter.SetHashAlgorithm("SHA256");
        return asymmetricSignatureDeformatter;
    }

然后使用类似这样的东西来签名(已经编辑了一些不相关的位):

    public XmlElement SignDocument(XmlDocument doc, List<string> idsToSign)
    {
        CryptoConfig.AddAlgorithm(typeof(RsaPkCs1Sha256SignatureDescription), @"http://www.w3.org/2001/04/xmldsig-more#rsa-sha256");

        var cspParams = new CspParameters(24) { KeyContainerName = "XML_DISG_RSA_KEY" };
        var key = new RSACryptoServiceProvider(cspParams);
        key.FromXmlString(_x509SecurityToken.Certificate.PrivateKey.ToXmlString(true));

        var signer = new SoapSignedXml(doc) { SigningKey = key };

        signer.SignedInfo.CanonicalizationMethod = SignedXml.XmlDsigExcC14NTransformUrl;

        var keyInfo = new KeyInfo();
        keyInfo.AddClause(new SecurityTokenReference(_x509SecurityToken, SecurityTokenReference.SerializationOptions.Embedded));

        signer.KeyInfo = keyInfo;
        signer.SignedInfo.SignatureMethod = "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256";

        var cn14Transform = new XmlDsigExcC14NTransform();
        string referenceDigestMethod = "http://www.w3.org/2001/04/xmlenc#sha256";

        foreach (string id in idsToSign)
        {
            var reference = new Reference("#" + id);
            reference.AddTransform(cn14Transform);
            reference.DigestMethod = referenceDigestMethod;
            signer.AddReference(reference);
        }

        signer.ComputeSignature();

        return signer.GetXml();
    }

似乎有效并在另一端验证 OK。前几天使用 Holodeck 进行了测试，我认为它在签名元素中缺少的时间戳上失败了。

但是，附件的签名似乎是 .NET 中的一个真正问题 - 我认为根本不支持相关的转换。

关于C# 支持对单个 XML 元素进行 RSA SHA 256 签名，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17258800/