How to implement NCryptSignHash and NCryptVerifySignature in C#?

SUBRAMANIAN Prabhakaran 1 Reputation point
2021-12-08T06:59:39.787+00:00

Hi Team,
How to implement CNG Key storage functions NCryptSignHash and NCryptVerifySignature in C#?

https://learn.microsoft.com/en-us/windows/win32/seccng/cng-key-storage-functions

Please share me code in C#.

Regards,
Prabs

Windows API - Win32
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  1. Junjie Zhu - MSFT 13,226 Reputation points Microsoft Vendor
    2021-12-08T08:05:36.777+00:00

    Hello,
    Welcome to Microsoft Q&A!

    In C# you can use the SignHash and VerifyHash methods of the RSACryptoServiceProvider class, which computes the signature for the specified hash value and verifies that a digital signature is valid. Here is an example of verify signature.

     public static void VerifyLegacySignVerifyHash(bool useLegacySign, bool useLegacyVerify)  
            {  
                byte[] dataHash, signature;  
      
                using (HashAlgorithm hash = SHA256.Create())  
                {  
                    dataHash = hash.ComputeHash(TestData.HelloBytes);  
                }  
      
                using (var rsa = new RSACryptoServiceProvider())  
                {  
                    rsa.ImportParameters(TestData.RSA2048Params);  
      
                    signature = useLegacySign ?  
                        rsa.SignHash(dataHash, "SHA256") :  
                        rsa.SignHash(dataHash, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);  
                }  
      
                bool verified;  
      
                using (var rsa = new RSACryptoServiceProvider())  
                {  
                    rsa.ImportParameters(  
                        new RSAParameters  
                        {  
                            Modulus = TestData.RSA2048Params.Modulus,  
                            Exponent = TestData.RSA2048Params.Exponent,  
                        });  
      
                    verified = useLegacyVerify ?  
                        rsa.VerifyHash(dataHash, "SHA256", signature) :  
                        rsa.VerifyHash(dataHash, signature, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);  
                }  
      
                Assert.True(verified);  
            }  
    

    You can also load ncrypt.dll in c# by DllImport ,@Castorix31 already answered in your last question.

    Thank you.


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  2. Junjie Zhu - MSFT 13,226 Reputation points Microsoft Vendor
    2021-12-10T07:27:00.487+00:00

    In fact, the method of calling them is the same. I suggest you have a look at Castorix31's reply in your last qusetion How to implement NCryptEncrypt and NCryptDecrypt methods in C# using Microsoft Key Storage Provider? , Here is code sample [https://github.com/itbetaw/TPlus-.netCore-/search?q=NCryptSignHash].

        [DllImport("ncrypt.dll", CharSet=CharSet.None, ExactSpelling=false)]  
        public static extern uint NCryptSignHash(SafeNCryptKeyHandle hKey, ref BCrypt.BCRYPT_PSS_PADDING_INFO pPaddingInfo, byte[] pbHashValue, int cbHashValue, byte[] pbSignature, int cbSignature, out uint pcbResult, uint dwFlags);  
          
        [DllImport("ncrypt.dll", CharSet=CharSet.None, ExactSpelling=false)]  
        public static extern uint NCryptVerifySignature(SafeNCryptKeyHandle hKey, ref BCrypt.BCRYPT_PSS_PADDING_INFO pPaddingInfo, byte[] pbHashValue, int cbHashValue, byte[] pbSignature, int cbSignature, uint dwFlags);  
    
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