SSO SAML的签名XML签名验证（使用sha256）

Question

在Windows 2003服务器上使用VS 2008和.Net Framework 3.5。

为了安全起见，我们使用SAML实施了SSO。 我们在服务提供商端工作，我们验证从客户端系统生成的签名XML SAML Assertuib令牌。 截至目前，我们遇到的任何签名文档都使用了签名算法“rsa-sha1”，但现在我们有新客户发送带有签名算法的文件“rsa-sha256”，这就是问题的开始。

public static string VerifySignature()
{
    if (m_xmlDoc == null)
        return "Could not load XMLDocument ";

    try
    {
        XmlNamespaceManager nsm = new XmlNamespaceManager(new NameTable());
        nsm.AddNamespace("dsig", SignedXml.XmlDsigNamespaceUrl);
        XmlElement sigElt = (XmlElement)m_xmlDoc.SelectSingleNode(
            "//dsig:Signature", nsm);

        // Load the signature for verification
        SignedXml sig = new SignedXml(m_xmlDoc);
        sig.LoadXml(sigElt);

        if (!sig.CheckSignature())
            return "Invalid Signature";
    }
    catch (Exception ex)
    {
        return ex.Message;
    }
    return string.Empty;
}

现在，当我为这个新客户尝试相同的代码（使用签名算法rsa-sha256h）时 - 这不起作用，我收到错误“无法为提供的签名算法创建SignatureDescription。”

在过去2-3天内浏览了许多博客和文章，我发现SignedXml不支持sha256。 精细。 但接下来是什么。 在其提到的某个地方使用WIF，我也检查过并试过这个 。

我也在尝试使用RSAPKCS1SignatureDeformatter的VerifySignature方法。 但不确定要传递的两个参数是什么。

Answer 1

Dotnet 4.6.2+内置了较新的sha哈希。对于dotnet 4 +，要访问rsa-sha512，rsa-sha384和rsa-sha256，你应该在某个地方包含这个代码。

/// <summary>Declare the signature type for rsa-sha512</summary>
public class RsaPkCs1Sha512SignatureDescription : SignatureDescription
{
    public RsaPkCs1Sha512SignatureDescription()
    {
        KeyAlgorithm = typeof(RSACryptoServiceProvider).FullName;
        DigestAlgorithm = typeof(SHA512CryptoServiceProvider).FullName;
        FormatterAlgorithm = typeof(RSAPKCS1SignatureFormatter).FullName;
        DeformatterAlgorithm = typeof(RSAPKCS1SignatureDeformatter).FullName;
    }

    public override AsymmetricSignatureDeformatter CreateDeformatter(AsymmetricAlgorithm key)
    {
        var sigProcessor = (AsymmetricSignatureDeformatter)CryptoConfig.CreateFromName(DeformatterAlgorithm);
        sigProcessor.SetKey(key);
        sigProcessor.SetHashAlgorithm("SHA512");
        return sigProcessor;
    }

    public override AsymmetricSignatureFormatter CreateFormatter(AsymmetricAlgorithm key)
    {
        var sigProcessor =
            (AsymmetricSignatureFormatter)CryptoConfig.CreateFromName(FormatterAlgorithm);
        sigProcessor.SetKey(key);
        sigProcessor.SetHashAlgorithm("SHA512");
        return sigProcessor;
    }
}

/// <summary>Declare the signature type for rsa-sha384</summary>
public class RsaPkCs1Sha384SignatureDescription : SignatureDescription {
    public RsaPkCs1Sha384SignatureDescription()
    {
        KeyAlgorithm = typeof(RSACryptoServiceProvider).FullName;
        DigestAlgorithm = typeof(SHA384CryptoServiceProvider).FullName;
        FormatterAlgorithm = typeof(RSAPKCS1SignatureFormatter).FullName;
        DeformatterAlgorithm = typeof(RSAPKCS1SignatureDeformatter).FullName;
    }

    public override AsymmetricSignatureDeformatter CreateDeformatter(AsymmetricAlgorithm key)
    {
        var sigProcessor = (AsymmetricSignatureDeformatter) CryptoConfig.CreateFromName(DeformatterAlgorithm);
        sigProcessor.SetKey(key);
        sigProcessor.SetHashAlgorithm("SHA384");
        return sigProcessor;
    }

    public override AsymmetricSignatureFormatter CreateFormatter(AsymmetricAlgorithm key)
    {
        var sigProcessor =
            (AsymmetricSignatureFormatter)CryptoConfig.CreateFromName(FormatterAlgorithm);
        sigProcessor.SetKey(key);
        sigProcessor.SetHashAlgorithm("SHA384");
        return sigProcessor;
    }
}

/// <summary>Declare the signature type for rsa-sha256</summary>
public class RsaPkCs1Sha256SignatureDescription : SignatureDescription
{
    public RsaPkCs1Sha256SignatureDescription()
    {
        KeyAlgorithm = typeof(RSACryptoServiceProvider).FullName;
        DigestAlgorithm = typeof(SHA256CryptoServiceProvider).FullName;
        FormatterAlgorithm = typeof(RSAPKCS1SignatureFormatter).FullName;
        DeformatterAlgorithm = typeof(RSAPKCS1SignatureDeformatter).FullName;
    }

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

    public override AsymmetricSignatureFormatter CreateFormatter(AsymmetricAlgorithm key)
    {
        var sigProcessor =
            (AsymmetricSignatureFormatter)CryptoConfig.CreateFromName(FormatterAlgorithm);
        sigProcessor.SetKey(key);
        sigProcessor.SetHashAlgorithm("SHA256");
        return sigProcessor;
    }
}

然后，您应该通过调用这样的代码来激活这些sig描述。 您只需要调用一次，因此如果您愿意，可以从静态构造函数中调用它。

    CryptoConfig.AddAlgorithm(typeof(RsaPkCs1Sha512SignatureDescription),
        "http://www.w3.org/2001/04/xmldsig-more#rsa-sha512");
    CryptoConfig.AddAlgorithm(typeof(RsaPkCs1Sha384SignatureDescription),
        "http://www.w3.org/2001/04/xmldsig-more#rsa-sha384");
    CryptoConfig.AddAlgorithm(typeof(RsaPkCs1Sha256SignatureDescription),
        "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256");

提示微软的Carlos Lopez和BitSchupster以及Andrew的SO。

Answer 2

对于.net 4及更早版本，我发现从http://clrsecurity.codeplex.com/添加Security.Cryptography后，以下工作正常。

（注意X509CertificateFinder是我自己的，通过指纹查找证书存储区中的签名证书）

        /// <summary>
        /// Validate an XmlDocuments signature
        /// </summary>
        /// <param name="xnlDoc"> The saml response with the signature elemenet to validate </param>
        /// <returns> True if signature can be validated with certificate </returns>
        public bool ValidateX509CertificateSignature(XmlDocument xnlDoc)
        {
            XmlNodeList XMLSignatures = xnlDoc.GetElementsByTagName("Signature", "http://www.w3.org/2000/09/xmldsig#");

            // Checking If the Response or the Assertion has been signed once and only once.
            if (XMLSignatures.Count != 1) return false;

            var signedXmlDoc = new SignedXml(xnlDoc);
            signedXmlDoc.LoadXml((XmlElement)XMLSignatures[0]);

            var certFinder = new X509CertificateFinder();
            var foundCert = certFinder.GetSignatureCertificate();

            CryptoConfig.AddAlgorithm(typeof(RSAPKCS1SHA256SignatureDescription), "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256");
            return signedXmlDoc.CheckSignature(foundCert,false);
        }

Answer 3

这符合“简单”但可能不是“解决方案”的条件:)对于我们遇到过的少数客户，我们已经要求他们使用SHA-1将他们的IdP更改为签名。 他们能够改变它，当他们这样做时。

不是技术解决方案，但它在“现场”工作，所以我想我会提到它。

Answer 4

只需将其更新到.NET framework 4.6.01590或更高版本，它将支持SHA-512而无需更改任何代码。