private byte[] ComputeHMacSHA256(string data, byte[] key)
{
var hmacSha256Algorism = new HMac(new Sha256Digest());
hmacSha256Algorism.Init(new KeyParameter(key));
var dataUtf8 = Encoding.UTF8.GetBytes(data);
hmacSha256Algorism.BlockUpdate(dataUtf8, 0, dataUtf8.Length);
var result = new byte[hmacSha256Algorism.GetUnderlyingDigest().GetDigestSize()];
hmacSha256Algorism.DoFinal(result, 0);
return(result);
}