I have one function witch check signature.

public static bool CheckSignature(string key64, string sig64)
{
var key = Convert.FromBase64String(key64);
var sig = Convert.FromBase64String(sig64);

        var rsa = new RSACryptoServiceProvider(new CspParameters
        {
            Flags = CspProviderFlags.UseMachineKeyStore
        });
        rsa.FromXmlString("4IlzOY3Y9fXoh3Y5f06wBbtTg94Pt6vcfcd1KQ0FLm0S36aGJtTSb6pYKfyX7PqCUQ8wgL6xUJ5GRPEsu9 gyz8ZobwfZsGCsvu40CWoT9fcFBZPfXro1Vtlh/xl/yYHm+Gzqh0Bw76xtLHSfLfpVOrmZdwKmSFKMTvNXOFd0V18=AQAB");
        var def = new RSAPKCS1SignatureDeformatter();
        def.SetKey(rsa);
        def.SetHashAlgorithm("MD5");

        return def.VerifySignature(key, sig);

    }

Now i need to create signature for one of my keys.

   public static byte\[\] CreateSignature(string key64)
    {
        var data = Convert.FromBase64String(key64);

        var rSaCryptoServiceProvider = new RSACryptoServiceProvider(new CspParameters
        {
           Flags = CspProviderFlags.UseMachineKeyStore
        });

        rSaCryptoServiceProvider.FromXmlString("4IlzOY3Y9fXoh3Y5f06wBbtTg94Pt6vcfcd1KQ0FLm0S36aGJtTSb6pYKfyX7PqCUQ8wgL6xUJ5GRPEsu9 gyz8ZobwfZsGCsvu40CWoT9fcFBZPfXro1Vtlh/xl/yYHm+Gzqh0Bw76xtLHSfLfpVOrmZdwKmSFKMTvNXOFd0V18=AQAB");
      

        var RSAform = new RSAPKCS1SignatureFormatter();
        RSAform.SetKey(rSaCryptoServiceProvider);
        RSAform.SetHashAlgorithm("MD5");

        byte\[\] hashData = CalculateMD5Hash(data);

        return RSAform.CreateSignature(hashData);
    }

But im getting an exception "Keyset does not exist" on "RSAform.CreateSignature(hashData)" line. Any suggestion?

Still amater