Device Validation

{
  "deviceId": "WillyNB",
  "hostName": "CCP-IoTHub-Dev.azure-devices.net",
  "symmetricKey": {
    "primaryKey": "myoJyBj6YKkZZk7WwZgzmXNi/+tVBzMEM3XLWhIBv4w=",
    "secondaryKey": "3lq24daPO51sk382haQl1WhZZbDBDXC/K8Jwm7yrQbY="
  },
  "azureIoTHubConnectionString": "HostName=CCP-IoTHub-Dev.azure-devices.net;DeviceId=WillyNB;SharedAccessKey=myoJyBj6YKkZZk7WwZgzmXNi/+tVBzMEM3XLWhIBv4w="
}

[TestClass]
public class IoTDeviceValidationUnitTest
{
    // 測試主機
    private const string ApiBaseAddress = "https://ccp-iot-api-dev.core-pcloud.com/";
    // CCP 自訂的 Scheme
    private const string AuthorizationHeaderScheme = "CCP-HMAC-KEY";

    // 測試裝置的 GUID
    private const string DeviceGuid = "956D5BE6-AFE0-499E-A579-F08CD684D23D";
    // 測試裝置的 SecretKey，註冊時提供，一定要記錄下來，因無法再向系統取得
    private const string DeviceSecretKey = "myoJyBj6YKkZZk7WwZgzmXNi/+tVBzMEM3XLWhIBv4w=";

    /// <summary>
    /// Validations the using hmac authentication test method.
    /// </summary>
    [TestMethod]
    public void ValidationUsingHmacAuthenticationTestMethod()
    {
        ValidationAsync().Wait();
    }

    /// <summary>
    /// Validations the asynchronous.
    /// </summary>
    private static async Task ValidationAsync()
    {
        Console.WriteLine("Calling the back-end API");
        Console.WriteLine($"Back-end API Server: {ApiBaseAddress}");
        var requestUri = $"{ApiBaseAddress}api/Devices/Validation/{DeviceGuid}";
        Console.WriteLine($"Request Uri: {requestUri}");
        Console.WriteLine();

        var customDelegatingHandler = new HMACAuthenticationDelegatingHandler(DeviceGuid, DeviceSecretKey, AuthorizationHeaderScheme)
        {
            InnerHandler = new HttpClientHandler()
        };

        var client = new HttpClient(customDelegatingHandler);

        var response = await client.GetAsync(requestUri);
        if (response.IsSuccessStatusCode)
        {
            var responseString = await response.Content.ReadAsStringAsync();
            Console.WriteLine();
            Console.WriteLine(responseString);
            Console.WriteLine("HTTP Status: {0}, Reason {1}. Press ENTER to exit", response.StatusCode,
                response.ReasonPhrase);
        }
        else
        {
            Console.WriteLine("Failed to call the API. HTTP Status: {0}, Reason {1}", response.StatusCode, response.ReasonPhrase);
        }

        Assert.AreEqual(response.StatusCode, HttpStatusCode.OK);
    }
}

/// <summary>
/// HMAC 驗證 Header 產生方式
/// </summary>
/// <seealso cref="DelegatingHandler" />
public class HMACAuthenticationDelegatingHandler : DelegatingHandler
{
    private readonly string _deviceGuid;
    private readonly string _deviceSecretKey;
    private readonly string _authorizationHeaderScheme;

    public HMACAuthenticationDelegatingHandler(string deviceGuid, string deviceSecretKey, string authorizationHeaderScheme)
    {
        _deviceGuid = deviceGuid;
        _deviceSecretKey = deviceSecretKey;
        _authorizationHeaderScheme = authorizationHeaderScheme;
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var requestUri = HttpUtility.UrlEncode(request.RequestUri.ToString());

        var requestHttpMethod = request.Method.Method;

        //Create random nonce for each request
        string nonce = Guid.NewGuid().ToString("N");
        
        //Calculate UNIX time
        var requestTimeStamp = DateTimeOffset.UtcNow.ToUnixTimeSeconds().ToString();

        //Creating the raw signature string
        var signatureRawData = $"{_deviceGuid}{requestHttpMethod}{requestUri}{requestTimeStamp}{nonce}";

        Console.WriteLine("Signature Raw Data : " + signatureRawData);
        Console.WriteLine();

        var secretKeyByteArray = Encoding.UTF8.GetBytes(_deviceSecretKey);

        var signature = Encoding.UTF8.GetBytes(signatureRawData);

        using (var hmac = new HMACSHA256(secretKeyByteArray))
        {
            var signatureBytes = hmac.ComputeHash(signature);
            var requestSignatureBase64String = Convert.ToBase64String(signatureBytes);

            //Setting the values in the Authorization header using custom scheme
            request.Headers.Authorization = new AuthenticationHeaderValue(_authorizationHeaderScheme,
                $"{_deviceGuid}:{requestSignatureBase64String}:{nonce}:{requestTimeStamp}");

            Console.WriteLine("Headers Authorization : " + request.Headers.Authorization);
            Console.WriteLine();
        }

        var response = await base.SendAsync(request, cancellationToken);

        return response;
    }
}