Azure IoT 中級（4）-（案例2）使用DPS通過對稱密鑰進行設備組註冊
視頻講解：
您可以在B站觀看視頻講解：https://www.bilibili.com/video/av92782084/
圖文講解：
1. 在DPS添加組註冊：
注意：組註冊中，沒有註冊ID的概念，也沒有Device ID的概念。
機制
有三種：x509證書，對稱密鑰
在本例中，我們使用對稱密鑰方式以便我們快速理解和驗證組註冊的業務邏輯；
密鑰我們採用自動生成，當然也可以手動輸入符合要求的自定義密鑰；
注意：本文中使用對稱密鑰方式做演示，後續章節介紹X509證書的方式，證書也是推薦的海量設備方案中應用的方案。
如何分配設備到中心
最低延遲：將設備預配到具有最低延遲的 IoT 中心，注意最低延遲不是指地理位置，例如中國北部的設備根據網絡情況可能出現分配到中國東部IoT Hub的情況。
均勻加權分發（默認）：鏈接的 IoT 中心等可能地獲得預配到它們的設備。 此設置爲默認設置。 如果只將設備預配到一個 IoT 中心，則可以保留此設置。
通過註冊列表進行靜態配置：註冊列表中所需 IoT 中心的規範優先於設備預配服務級別的分配策略。
使用Azure Function（自定義）：該方案可以使用自定義邏輯判斷分發到哪個IoT Hub。
在本例中，我們只配置了一個IoT Hub，因此採用默認的均勻加權即可。
初始設備孿生狀態
例如可以設置版本號爲 1.11，會按照device twin的邏輯進行版本升級；
添加之後的狀態爲：
註冊記錄爲空：
2.準備示例代碼
項目中使用的示例代碼，https://codeload.github.com/Azure-Samples/azure-iot-samples-csharp/zip/master
關鍵處請參加如下代碼中的中文註釋：
// Copyright (c) Microsoft. All rights reserved.// Licensed under the MIT license. See LICENSE file in the project root for full license information.using Microsoft.Azure.Devices.Provisioning.Client;using Microsoft.Azure.Devices.Provisioning.Client.Samples;using Microsoft.Azure.Devices.Provisioning.Client.Transport;using Microsoft.Azure.Devices.Shared;using System;using System.Security.Cryptography;using System.Text;namespace SymmetricKeySample{ class Program
{ // The Provisioning Hub IDScope.
// For this sample either:
// - pass this value as a command-prompt argument
// - set the DPS_IDSCOPE environment variable
// - create a launchSettings.json (see launchSettings.json.template) containing the variable
//private static string s_idScope = Environment.GetEnvironmentVariable("DPS_IDSCOPE");
private static string s_idScope = "此處需要修改成dps的ID"; // In your Device Provisioning Service please go to "Manage enrollments" and select "Individual Enrollments".
// Select "Add individual enrollment" then fill in the following:
// Mechanism: Symmetric Key
// Auto-generate keys should be checked
// DeviceID: iothubSymmetricKeydevice1
// Symmetric Keys may also be used for enrollment groups.
// In your Device Provisioning Service please go to "Manage enrollments" and select "Enrollment Groups".
// Select "Add enrollment group" then fill in the following:
// Group name: <your group name>
// Attestation Type: Symmetric Key
// Auto-generate keys should be checked
// You may also change other enrollment group parameters according to your needs
//private const string GlobalDeviceEndpoint = "global.azure-devices-provisioning.net";
//此處應該改成中國的終結點.CN結尾
private const string GlobalDeviceEndpoint = "global.azure-devices-provisioning.cn"; //These are the two keys that belong to your enrollment group.
// Leave them blank if you want to try this sample for an individual enrollment instead
private const string enrollmentGroupPrimaryKey = "僅當使用組註冊時，必須填寫此值"; private const string enrollmentGroupSecondaryKey = "僅當使用組註冊時，必須填寫此值"; //registration id for enrollment groups can be chosen arbitrarily and do not require any portal setup.
//The chosen value will become the provisioned device's device id.
//
//registration id for individual enrollments must be retrieved from the portal and will be unrelated to the provioned
//device's device id
//
//This field is mandatory to provide for this sample
private static string registrationId = "對於組註冊，此處爲待註冊的設備DeviceID，通常填寫諸如MAC地址等唯一值"; //These are the two keys that belong to your individual enrollment.
// Leave them blank if you want to try this sample for an individual enrollment instead
private const string individualEnrollmentPrimaryKey = ""; private const string individualEnrollmentSecondaryKey = ""; public static int Main(string[] args)
{ if (string.IsNullOrWhiteSpace(s_idScope) && (args.Length > 0))
{
s_idScope = args[0];
} if (string.IsNullOrWhiteSpace(s_idScope))
{
Console.WriteLine("ProvisioningDeviceClientSymmetricKey <IDScope>"); return 1;
} string primaryKey = ""; string secondaryKey = ""; if (!String.IsNullOrEmpty(registrationId) && !String.IsNullOrEmpty(enrollmentGroupPrimaryKey) && !String.IsNullOrEmpty(enrollmentGroupSecondaryKey))
{ //Group enrollment flow, the primary and secondary keys are derived from the enrollment group keys and from the desired registration id
//注意，此處的primaryKey和secondryKey即IoT Hub中新增Device 的primaryKey和secondryKey
primaryKey = ComputeDerivedSymmetricKey(Convert.FromBase64String(enrollmentGroupPrimaryKey), registrationId);
secondaryKey = ComputeDerivedSymmetricKey(Convert.FromBase64String(enrollmentGroupSecondaryKey), registrationId);
} else if (!String.IsNullOrEmpty(registrationId) && !String.IsNullOrEmpty(individualEnrollmentPrimaryKey) && !String.IsNullOrEmpty(individualEnrollmentSecondaryKey))
{ //Individual enrollment flow, the primary and secondary keys are the same as the individual enrollment keys
primaryKey = individualEnrollmentPrimaryKey;
secondaryKey = individualEnrollmentSecondaryKey;
} else
{
Console.WriteLine("Invalid configuration provided, must provide group enrollment keys or individual enrollment keys"); return -1;
} using (var security = new SecurityProviderSymmetricKey(registrationId, primaryKey, secondaryKey)) // Select one of the available transports:
// To optimize for size, reference only the protocols used by your application.
using (var transport = new ProvisioningTransportHandlerAmqp(TransportFallbackType.TcpOnly)) // using (var transport = new ProvisioningTransportHandlerHttp())
// using (var transport = new ProvisioningTransportHandlerMqtt(TransportFallbackType.TcpOnly))
// using (var transport = new ProvisioningTransportHandlerMqtt(TransportFallbackType.WebSocketOnly))
{
ProvisioningDeviceClient provClient =
ProvisioningDeviceClient.Create(GlobalDeviceEndpoint, s_idScope, security, transport); var sample = new ProvisioningDeviceClientSample(provClient, security);
sample.RunSampleAsync().GetAwaiter().GetResult();
}
Console.WriteLine("Enter any key to exit");
Console.ReadLine(); return 0;
} /// <summary>
/// Generate the derived symmetric key for the provisioned device from the enrollment group symmetric key used in attestation
/// </summary>
/// <param name="masterKey">Symmetric key enrollment group primary/secondary key value</param>
/// <param name="registrationId">the registration id to create</param>
/// <returns>the primary/secondary key for the member of the enrollment group</returns>
public static string ComputeDerivedSymmetricKey(byte[] masterKey, string registrationId)
{ using (var hmac = new HMACSHA256(masterKey))
{ return Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(registrationId)));
}
}
}
}
3.運行程序，得到分配的IoT Hub名稱以及DeviceID
設備側程序可以得到IoT Hub的名稱，設備的ID，加上代碼裏的key，則具備了連接IoT Hub的所有參數，此時可以直接連接到IoT Hub。
此時，可以在組註冊中的註冊列表中看到對應的註冊記錄：
此時，在IoT Hub中能夠看到由DPS註冊過來的Device:
將代碼中的 private static string registrationId = "對於組註冊，此處爲待註冊的設備DeviceID，通常填寫諸如MAC地址等唯一值"; 替換，可以通過DPS的這個組註冊添加多臺設備到IoT Hub中：
