是否可以使用RSA SHA512对哈希进行签名？

Question

我使用OpenSSL创建了一个自签名证书，如下所示：

然后，我在C#.NET4.0中编写了以下代码：

public static bool DSHandler(string operation, string path, string devicePath)
{
    bool result = false;
        CryptoConfig.AddAlgorithm(typeof(USBSaferAppEFB.RsaPkCs1Sha512SignatureDescription),
            "http://www.w3.org/2001/04/xmldsig-more#rsa-sha512");
        string password = "xxxx";
        bool validSignature = false;
        byte[] hashchain = generateHash(path);
        string digSignFile = Utils.RegVarValue(DIGSIGNFILE);
        string subjectDN = Utils.RegVarValue(SUBJECTDN);

        if (operation == "sign")
        {
            byte[] signature = SignFromContainer(hashchain, subjectDN);
            if (signature != null)
            {
                string signaturestring = Convert.ToBase64String(signature);

                File.WriteAllBytes(devicePath + digSignFile, signature);
                result = true;
            }
            else
                result = false;
        }
}

static byte[] SignFromContainer(byte[] hashchain, string certSubject)
{
    try
    {
        X509Store my = new X509Store(StoreName.My, StoreLocation.CurrentUser);
        my.Open(OpenFlags.ReadOnly);
        RSACryptoServiceProvider csp = null;
        foreach (X509Certificate2 cert in my.Certificates)
        {
            if (cert.Subject.Contains(certSubject))
            {
                // We found it.
                // Get its associated CSP and private key
                csp = (RSACryptoServiceProvider)cert.PrivateKey;
            }
        }

        if (csp == null)
        {
            return null;
        }

        byte[] myHash = { 59,4,248,102,77,97,142,201,
        210,12,224,93,25,41,100,197,
        210,12,224,93};

        // Sign the hash
        return csp.SignHash(hashchain, CryptoConfig.MapNameToOID("SHA-512"));
    }
    catch (Exception e)
    {
        log.Logger("Exception: "+e.Message, "debug");
        log.Logger(e.StackTrace, "debug");
        return null;
    }
}

使用一些文章和答案中的解决方案，我有RSAPKCS1SHA512SignatureDescription类，我试图在其中实现和注册签名描述：

public 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)
    {
        var sigProcessor = (AsymmetricSignatureDeformatter)CryptoConfig.CreateFromName(DeformatterAlgorithm);
        sigProcessor.SetKey(key);
        sigProcessor.SetHashAlgorithm("SHA-512");
        return sigProcessor;
    }

    public override AsymmetricSignatureFormatter CreateFormatter(AsymmetricAlgorithm key)
    {
        var sigProcessor =
            (AsymmetricSignatureFormatter)CryptoConfig.CreateFromName(FormatterAlgorithm);
        sigProcessor.SetKey(key);
        sigProcessor.SetHashAlgorithm("SHA-512");
        return sigProcessor;
    }
}

我已经验证了hash的长度为64字节，它返回一个CryptographicException:Bad hash。但是如果我使用myhashvar(20字节长），尽管signhash中指定的算法是SHA512，但它可以工作，并使用SHA1算法对哈希进行签名。

另外，如果我打印csp.signaturealgorithm，它的值是http://www.w3.org/2000/09/xmldsig#rsa-sha1。如果安装的证书的详细信息显示SHA512RSA为签名算法，为什么签名算法等于http://www.w3.org/2000/09/xmldsig#RSA-SHA1？这一点可能是真正的问题吗？如果是，如何正确创建证书？提前感谢！

Answer 1

NET 4.6中对此过程进行了简化：

byte[] signature;

using (RSA rsa = cert.GetRSAPrivateKey())
{
    signature = rsa.SignHash(hash, HashAlgorithmName.SHA512, RSASignaturePadding.Pkcs1);
}

请注意，.NET4.6RSA类型不再需要强制转换为RSACryptoServiceProvider，如果您使用GetRSAPrivateKey（）（而不是PrivateKey属性），返回的对象很可能处理SHA-512签名生成。GetRSAPrivateKey每次还返回一个唯一的对象，因此您应该适当地处理它。