Azure IoT 中级（4）-（案例2）使用DPS通过对称密钥进行设备组注册
视频讲解：
您可以在B站观看视频讲解：https://www.bilibili.com/video/av92782084/
图文讲解：
1. 在DPS添加组注册：
注意：组注册中，没有注册ID的概念，也没有Device ID的概念。
机制
有三种：x509证书，对称密钥
在本例中，我们使用对称密钥方式以便我们快速理解和验证组注册的业务逻辑；
密钥我们采用自动生成，当然也可以手动输入符合要求的自定义密钥；
注意：本文中使用对称密钥方式做演示，后续章节介绍X509证书的方式，证书也是推荐的海量设备方案中应用的方案。
如何分配设备到中心
最低延迟：将设备预配到具有最低延迟的 IoT 中心，注意最低延迟不是指地理位置，例如中国北部的设备根据网络情况可能出现分配到中国东部IoT Hub的情况。
均匀加权分发（默认）：链接的 IoT 中心等可能地获得预配到它们的设备。 此设置为默认设置。 如果只将设备预配到一个 IoT 中心，则可以保留此设置。
通过注册列表进行静态配置：注册列表中所需 IoT 中心的规范优先于设备预配服务级别的分配策略。
使用Azure Function（自定义）：该方案可以使用自定义逻辑判断分发到哪个IoT Hub。
在本例中，我们只配置了一个IoT Hub，因此采用默认的均匀加权即可。
初始设备孪生状态
例如可以设置版本号为 1.11，会按照device twin的逻辑进行版本升级；
添加之后的状态为：
注册记录为空：
2.准备示例代码
项目中使用的示例代码，https://codeload.github.com/Azure-Samples/azure-iot-samples-csharp/zip/master
关键处请参加如下代码中的中文注释：
// 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 = "此处需要修改成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:
// 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";
//此处应该改成中国的终结点.CN结尾
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 = "仅当使用组注册时，必须填写此值"; private const string enrollmentGroupSecondaryKey = "仅当使用组注册时，必须填写此值"; //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 = "对于组注册，此处为待注册的设备DeviceID，通常填写诸如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 "); 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，此处的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;
} ///
/// Generate the derived symmetric key for the provisioned device from the enrollment group symmetric key used in attestation
///
/// Symmetric key enrollment group primary/secondary key value
/// the registration id to create
/// the primary/secondary key for the member of the enrollment group
public static string ComputeDerivedSymmetricKey(byte[] masterKey, string registrationId)
{ using (var hmac = new HMACSHA256(masterKey))
{ return Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(registrationId)));
}
}
}
}
3.运行程序，得到分配的IoT Hub名称以及DeviceID
设备侧程序可以得到IoT Hub的名称，设备的ID，加上代码里的key，则具备了连接IoT Hub的所有参数，此时可以直接连接到IoT Hub。
此时，可以在组注册中的注册列表中看到对应的注册记录：
此时，在IoT Hub中能够看到由DPS注册过来的Device:
将代码中的 private static string registrationId = "对于组注册，此处为待注册的设备DeviceID，通常填写诸如MAC地址等唯一值"; 替换，可以通过DPS的这个组注册添加多台设备到IoT Hub中：
