X509certificates containing ECDSA Example

dotnet-461-crypto.cs

// Current approach
public class Net46Approach
    {
        public static byte[] SignECDsaSha512(byte[] data, X509Certificate2 cert)
        {
            // This would require using cert.Handle and a series of p/invokes to get at the
            // underlying key, then passing that to a CngKey object, and passing that to
            // new ECDsa(CngKey).  It's a lot of work.
            throw new Exception("That's a lot of work...");
        }

        public static byte[] SignECDsaSha512(byte[] data, ECDsa privateKey)
        {
            // This way works, but SignData probably better matches what you want.
            using (SHA512 hasher = SHA512.Create())
            {
                byte[] signature1 = privateKey.SignHash(hasher.ComputeHash(data));
            }

            // This might not be the ECDSAsa you got!
            ECDsaCng ecDsaCng = (ECDsaCng)privateKey;
            ecDsaCng.HashAlgorithm = CngAlgorithm.Sha512;
            return ecDsaCng.SignData(data);
        }
    }


// The new way
public class Net461Approach
    {
        public static byte[] SignECDsaSha512(byte[] data, X509Certificate2 cert)
        {
            using (ECDsa privateKey = cert.GetECDsaPrivateKey())
            {
                return privateKey.SignData(data, HashAlgorithmName.SHA512);
            }
        }

        public static byte[] SignECDsaSha512(byte[] data, ECDsa privateKey)
        {
            return privateKey.SignData(data, HashAlgorithmName.SHA512);
        }
    }