如何在.NET中验证RSA-SHA512 XML签名？

Question

但是，当我收到SignatureMethod RSA-SHA512(http://www.w3.org/2001/04/xmldsig-more#RSA-SHA512)时，CheckSignature()会出现CryptograhicException中断：无法为提供的签名算法创建SignatureDescription。

看起来CheckSignature（）无法验证RSA-SHA512签名。

有没有人知道怎么检查这种签名？

从MSDN站点获取的代码为：

public static bool VerifyXml(XmlDocument doc, bool removeSignatureElement = false)
{
    // Check arguments.
    if (doc == null)
        throw new ArgumentException("doc");

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

    // Find the "Signature" node and create a new XmlNodeList object.
    XmlNodeList nodeList = doc.GetElementsByTagName("Signature", Constants.NamespaceDSig);

    // Throw an exception if no signature was found.
    if (nodeList.Count < 1)
    {
        throw new CryptographicException("Verification failed: No Signature was found in the document.");
    }

    // This example only supports one signature for the entire XML document.  Throw an exception if more than one signature was found.
    if (nodeList.Count > 1)
    {
        throw new CryptographicException("Verification failed: More that one signature was found for the document.");
    }

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

    // Check the signature and return the result.
    bool signedCorrectly = signedXml.CheckSignature(); // throws the Exception!!!

    return signedCorrectly;
}

签名的XML是：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Notification xmlns="http://www.xxxxxxxxxxx.xx/xxxxx">
    <xenc:EncryptedData xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" Type="http://www.w3.org/2001/04/xmlenc#Content"> ... </xenc:EncryptedData>
    <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
        <ds:SignedInfo>
            <ds:CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
            <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha512"/>
            <ds:Reference URI="">
                <ds:Transforms>
                    <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
                    <ds:Transform Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments"/>
                </ds:Transforms>
                <ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
                <ds:DigestValue>WsHcyNL7Jh8HSzR9ArzTqomBkHs=</ds:DigestValue>
            </ds:Reference>
        </ds:SignedInfo>
        <ds:SignatureValue>
pWDatSEbypIUVQR9NFmLkB9kKWjMb6rKWGFFvGqT5tOUILeDhMHUqjCRB9v/g6yYdogC9TRWouhz
...VoZAIBs7EqCbLt7RgpB4GHWc9E3qp65NaCgluw==
        </ds:SignatureValue>
        <ds:KeyInfo>
            <ds:X509Data>
                <ds:X509Certificate>
MIIG+zCCBOOgAwIBAgIHAe2+sRfTfDANBgkqhkiG9w0BAQUFADCBkTELMAkGA1UEBhMCQVQxDTAL
...tvawqBjOfkw1yeDzsDMJHfMuAcpYfrEL
                </ds:X509Certificate>
            </ds:X509Data>
        </ds:KeyInfo>
    </ds:Signature>
</Notification>

Answer 1

您可以验证RSA SHA512签名，但您必须自己实现和注册签名描述。

签名描述：

public sealed class RSAPKCS1SHA512SignatureDescription : SignatureDescription
{
    public RSAPKCS1SHA512SignatureDescription()
    {
        KeyAlgorithm = typeof( RSACryptoServiceProvider ).FullName;
        DigestAlgorithm = typeof( SHA512Managed ).FullName;
        FormatterAlgorithm = typeof( RSAPKCS1SignatureFormatter ).FullName;
        DeformatterAlgorithm = typeof( RSAPKCS1SignatureDeformatter ).FullName;
    }

    public override AsymmetricSignatureDeformatter CreateDeformatter( AsymmetricAlgorithm key )
    {
        if( key == null )
        {
            throw new ArgumentNullException( "key" );
        }

        var deformatter = new RSAPKCS1SignatureDeformatter( key );
        deformatter.SetHashAlgorithm( "SHA512" );
        return deformatter;
    }

    public override AsymmetricSignatureFormatter CreateFormatter( AsymmetricAlgorithm key )
    {
        if( key == null )
        {
            throw new ArgumentNullException( "key" );
        }

        var formatter = new RSAPKCS1SignatureFormatter( key );
        formatter.SetHashAlgorithm( "SHA512" );
        return formatter;
    }
}

在您的代码中，您必须向cryptoconfig注册此描述：

const string XmlDsigRsaSha512 = "http://www.w3.org/2001/04/xmldsig-more#rsa-sha512";
CryptoConfig.AddAlgorithm( typeof( RSAPKCS1SHA512SignatureDescription ), XmlDsigRsaSha512 );