c# base64url 和HMACSha256加密

 private static 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);
                Console.WriteLine(hashmessage);
                char[] padding = { '=' };
                //转换成base64url格式
                return Convert.ToBase64String(hashmessage, Base64FormattingOptions.None).TrimEnd(padding).Replace('+', '-').Replace('/', '_'); ;
            }
        }