如何使用DPS通过对称密钥进行设备组注册？

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

1. 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。

2. 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。

3. 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。

4. 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：