Lập Trình .NET

    private string HMACSHA256(string message, string secret)
    {
        secret = secret ?? "";
        var encoding = new System.Text.ASCIIEncoding();
        byte[] keyByte = encoding.GetBytes(secret);
        byte[] messageBytes = encoding.GetBytes(message);
        using (var hmacsha256 = new HMACSHA256(keyByte))
        {
            byte[] hashmessage = hmacsha256.ComputeHash(messageBytes);
            string sbinary = "";
            for (int i = 0; i < hashmessage.Length; i++)
            {
                sbinary += hashmessage[i].ToString("x2"); // hex format
            }
            return sbinary;
        }
    }