DPS freshness -- terminology

Author: kgremban

articles/iot-dps/concepts-service.md

@@ -1,62 +1,74 @@
 ---
 title: Terminology and glossary for Azure DPS
 titleSuffix: Azure IoT Hub Device Provisioning Service
-description: This article describes common terminology used with the Device Provisioning Service (DPS) and IoT Hub
+description: This article describes common terminology used with the Device Provisioning Service (DPS) and IoT Hub.
 author: kgremban
 
 ms.author: kgremban
-ms.date: 09/18/2019
+ms.date: 04/25/2024
 ms.topic: concept-article
 ms.service: iot-dps
 ---
 
-# IoT Hub Device Provisioning Service (DPS) terminology
+# IoT Hub Device Provisioning Service terminology
 
-IoT Hub Device Provisioning Service is a helper service for IoT Hub that you use to configure zero-touch device provisioning to a specified IoT hub. With the Device Provisioning Service, you can [provision](about-iot-dps.md#provisioning-process) millions of devices in a secure and scalable manner.
+IoT Hub Device Provisioning Service (DPS) is a helper service for IoT Hub that enables zero-touch device provisioning to IoT hubs. With the Device Provisioning Service, you can provision millions of devices in a secure and scalable manner.
 
-Device provisioning is a two part process. The first part is establishing the initial connection between the device and the IoT solution by *registering* the device. The second part is applying the proper *configuration* to the device based on the specific requirements of the solution. Once both steps have been completed, the device has been fully *provisioned*. Device Provisioning Service automates both steps to provide a seamless provisioning experience for the device.
+Device provisioning is a two part process.
 
-This article gives an overview of the provisioning concepts most applicable to managing the *service*. This article is most relevant to personas involved in the [cloud setup step](about-iot-dps.md#cloud-setup-step) of getting a device ready for deployment.
+1. The first part establishes the initial connection between the device and the IoT solution by *registering* the device.
+1. The second part applies the proper *configuration* to the device based on the specific requirements of the solution.
+
+Once both steps have been completed, the device has been fully *provisioned*. Device Provisioning Service automates both steps to provide a seamless provisioning experience for the device.
+
+This article gives an overview of the provisioning concepts applicable to managing the *service*. This article is most relevant to personas involved in the [cloud setup step](about-iot-dps.md#cloud-setup-step) of getting a device ready for deployment.
 
 ## Service operations endpoint
 
-The service operations endpoint is the endpoint for managing the service settings and maintaining the enrollment list. This endpoint is only used by the service administrator; it is not used by devices.
+The service operations endpoint is the endpoint for managing the service settings and maintaining the enrollment list. This endpoint is only used by the service administrator; it isn't used by devices.
 
 ## Device provisioning endpoint
 
-The device provisioning endpoint is the single endpoint all devices use for auto-provisioning. The URL is the same for all provisioning service instances, to eliminate the need to reflash devices with new connection information in supply chain scenarios. The ID scope ensures tenant isolation.
+The device provisioning endpoint is the single endpoint that all devices use for provisioning. The URL is the same for all provisioning service instances, which eliminates the need to reflash devices with new connection information in supply chain scenarios. The [ID scope](#id-scope) ensures tenant isolation.
 
 ## Linked IoT hubs
 
-The Device Provisioning Service can only provision devices to IoT hubs that have been linked to it. Linking an IoT hub to an instance of the Device Provisioning Service gives the service read/write permissions to the IoT hub's device registry; with the link, a Device Provisioning Service can register a device ID and set the initial configuration in the device twin. Linked IoT hubs may be in any Azure region. You may link hubs in other subscriptions to your provisioning service.
+The Device Provisioning Service can only provision devices to IoT hubs that have been linked to it. Linking an IoT hub to an instance of the Device Provisioning Service gives the service read/write permissions to the IoT hub's device registry. With the link, a Device Provisioning Service can register a device ID and set the initial configuration in the device twin. Linked IoT hubs may be in any Azure region. You can link hubs in other subscriptions to your provisioning service.
+
+For more information, see [How to link and manage IoT hubs](./how-to-manage-linked-iot-hubs.md)
 
 ## Allocation policy
 
-The service-level setting that determines how Device Provisioning Service assigns devices to an IoT hub. There are four supported allocation policies:
+The allocation policy is a service-level setting that determines how Device Provisioning Service assigns devices to an IoT hub. There are four supported allocation policies:
 
-* **Evenly weighted distribution**: linked IoT hubs are equally likely to have devices provisioned to them. The default setting. If you are provisioning devices to only one IoT hub, you can keep this setting.
+* **Evenly weighted distribution**: linked IoT hubs are equally likely to have devices provisioned to them. The default setting. If you're provisioning devices to only one IoT hub, you can keep this setting.
 
 * **Lowest latency**: devices are provisioned to an IoT hub with the lowest latency to the device. If multiple linked IoT hubs would provide the same lowest latency, the provisioning service hashes devices across those hubs
 
 * **Static configuration via the enrollment list**: specification of the desired IoT hub in the enrollment list takes priority over the service-level allocation policy.
 
-* **Custom (Use Azure Function)**: A [custom allocation policy](how-to-use-custom-allocation-policies.md) gives you more control over how devices are assigned to an IoT hub. This is accomplished by using custom code in an Azure Function to assign devices to an IoT hub. The device provisioning service calls your Azure Function code providing all relevant information about the device and the enrollment to your code. Your function code is executed and returns the IoT hub information used to provisioning the device.
+* **Custom (Use Azure Function)**: A custom allocation policy gives you more control over how devices are assigned to an IoT hub. Custom allocation policies use an Azure Function to assign devices to an IoT hub. The device provisioning service calls your Azure Function code providing all relevant information about the device and the enrollment to your code. Your function code is executed and returns the IoT hub information used to provisioning the device. For more information, see [Understand custom allocation policies](how-to-use-custom-allocation-policies.md).
+
+For more information, see [How to use allocation policies](./how-to-use-allocation-policies.md).
 
 ## Enrollment
 
-An enrollment is the record of devices or groups of devices that may register through auto-provisioning. The enrollment record contains information about the device or group of devices, including:
-- the [attestation mechanism](#attestation-mechanism) used by the device
-- the optional initial desired configuration
-- desired IoT hub
-- the desired device ID
+An enrollment is the record of devices or groups of devices that may register through autoprovisioning. The enrollment record contains information about the device or group of devices, including:
+
+* The [attestation mechanism](#attestation-mechanism) used by the device
+* The optional initial desired configuration
+* The desired IoT hub
+* The desired device ID
 
-There are two types of enrollments supported by Device Provisioning Service:
+There are two types of enrollments supported by Device Provisioning Service: enrollment groups and individual enrollments.
 
 ### Enrollment group
 
-An enrollment group is a group of devices that share a specific attestation mechanism. Enrollment groups support X.509 certificate or symmetric key attestation. Devices in an X.509 enrollment group present X.509 certificates that have been signed by the same root or intermediate Certificate Authority (CA). The subject common name (CN) of each device's end-entity (leaf) certificate becomes the registration ID for that device. Devices in a symmetric key enrollment group present SAS tokens derived from the group symmetric key.
+An enrollment group is a group of devices that share a specific attestation mechanism. Enrollment groups support X.509 certificate or symmetric key attestation.
+
+The name of the enrollment group and the registration IDs presented by devices must be case-insensitive strings of alphanumeric characters plus the special characters: `- . _ :`. The last character must be alphanumeric or dash (`-`). The enrollment group name can be up to 128 characters long. In symmetric key enrollment groups, the registration IDs presented by devices can be up to 128 characters long. However, in X.509 enrollment groups, because the maximum length of the subject common name in an X.509 certificate is 64 characters, the registration IDs are limited to 64 characters.
 
-The name of the enrollment group as well as the registration IDs presented by devices must be case-insensitive strings of alphanumeric characters plus the special characters: `'-'`, `'.'`, `'_'`, `':'`. The last character must be alphanumeric or dash (`'-'`). The enrollment group name can be up to 128 characters long. In symmetric key enrollment groups, the registration IDs presented by devices can be up to 128 characters long. However, in X.509 enrollment groups, because the maximum length of the subject common name in an X.509 certificate is 64 characters, the registration IDs are limited to 64 characters.
+Devices in an X.509 enrollment group present X.509 certificates that are signed by the same root or intermediate Certificate Authority (CA). The subject common name (CN) of each device's end-entity (leaf) certificate becomes the registration ID for that device. Devices in a symmetric key enrollment group present SAS tokens derived from the group symmetric key.
 
 For devices in an enrollment group, the registration ID is also used as the device ID that is registered to IoT Hub.
 
@@ -65,13 +77,13 @@ For devices in an enrollment group, the registration ID is also used as the devi
 
 ### Individual enrollment
 
-An individual enrollment is an entry for a single device that may register. Individual enrollments may use either X.509 leaf certificates or SAS tokens (from a physical or virtual TPM) as the attestation mechanisms. The registration ID in an individual enrollment is a case-insensitive string of alphanumeric characters plus the special characters: `'-'`, `'.'`, `'_'`, `':'`. The last character must be alphanumeric or dash (`'-'`). DPS supports registration IDs up to 128 characters long.
+An individual enrollment is an entry for a single device that may register. Individual enrollments can use either X.509 leaf certificates or SAS tokens (from a physical or virtual TPM) as the attestation mechanisms.
 
-For X.509 individual enrollments, the subject common name (CN) of the certificate becomes the registration ID, so the common name must adhere to the registration ID string format. The subject common name has a maximum length of 64 characters, so the registration ID is limited to 64 characters for X.509 enrollments.
+The registration ID in an individual enrollment is a case-insensitive string of alphanumeric characters plus the special characters: `- . _ :`. The last character must be alphanumeric or dash (`-`). DPS supports registration IDs up to 128 characters long.
 
-Individual enrollments may have the desired IoT hub device ID specified in the enrollment entry. If it's not specified, the registration ID becomes the device ID that's registered to IoT Hub.
+For X.509 individual enrollments, the subject common name (CN) of the certificate must match the registration ID, so the common name must adhere to the registration ID string format. The subject common name has a maximum length of 64 characters, so the registration ID is limited to 64 characters for X.509 enrollments.
 
-You can temporarily or permanently allow or block a specific device from being provisioning through the Device Provisioning Service by controlling [provisioning status of an enrollment](how-to-revoke-device-access-portal.md)
+Individual enrollments may have the desired IoT hub device ID specified in the enrollment entry. If it's not specified, the registration ID becomes the device ID that's registered to IoT Hub.
 
 > [!TIP]
 > We recommend using individual enrollments for devices that require unique initial configurations, or for devices that can only authenticate using SAS tokens via TPM attestation.
@@ -84,41 +96,39 @@ An attestation mechanism is the method used for confirming a device's identity.
 > IoT Hub uses "authentication scheme" for a similar concept in that service.
 
 The Device Provisioning Service supports the following forms of attestation:
+
 * **X.509 certificates** based on the standard X.509 certificate authentication flow. For more information, see [X.509 attestation](concepts-x509-attestation.md).
-* **Trusted Platform Module (TPM)** based on a nonce challenge, using the TPM standard for keys to present a signed Shared Access Signature (SAS) token. This does not require a physical TPM on the device, but the service expects to attest using the endorsement key per the [TPM spec](https://trustedcomputinggroup.org/work-groups/trusted-platform-module/). For more information, see [TPM attestation](concepts-tpm-attestation.md).
+* **Trusted Platform Module (TPM)** based on a nonce challenge, using the TPM standard for keys to present a signed Shared Access Signature (SAS) token. This doesn't require a physical TPM on the device, but the service expects to attest using the endorsement key per the [TPM spec](https://trustedcomputinggroup.org/work-groups/trusted-platform-module/). For more information, see [TPM attestation](concepts-tpm-attestation.md).
 * **Symmetric Key** based on shared access signature (SAS) [SAS tokens](../iot-hub/iot-hub-dev-guide-sas.md#sas-tokens), which include a hashed signature and an embedded expiration. For more information, see [Symmetric key attestation](concepts-symmetric-key-attestation.md).
 
 ## Hardware security module
 
-The hardware security module, or HSM, is used for secure, hardware-based storage of device secrets, and is the most secure form of secret storage. Both X.509 certificates and SAS tokens can be stored in the HSM. HSMs can be used with both attestation mechanisms the provisioning service supports.
+A hardware security module, or HSM, is used for secure, hardware-based storage of device secrets, and is the most secure form of secret storage. Both X.509 certificates and SAS tokens can be stored in an HSM.
 
 > [!TIP]
 > We strongly recommend using an HSM with devices to securely store secrets on your devices.
 
-Device secrets may also be stored in software (memory), but it is a less secure form of storage than an HSM.
+Device secrets can also be stored in software (memory), but it's a less secure form of storage than an HSM.
 
 ## ID scope
 
-The ID scope is assigned to a Device Provisioning Service when it is created by the user and is used to uniquely identify the specific provisioning service the device will register through. The ID scope is generated by the service and is immutable, which guarantees uniqueness.
-
-> [!NOTE]
-> Uniqueness is important for long-running deployment operations and merger and acquisition scenarios.
+The ID scope is assigned to a Device Provisioning Service when it's created and is used to uniquely identify the specific provisioning service. The ID scope is generated by the service and is immutable, which guarantees uniqueness. ID scope uniqueness is important for long-running deployment operations and merger and acquisition scenarios.
 
 ## Registration Record
 
-A registration record is the record of a device successfully registering/provisioning to an IoT Hub via the Device Provisioning Service. Registration records are created automatically; they can be deleted, but they cannot be updated.
+A registration record is the record of a device successfully registering/provisioning to an IoT Hub via the Device Provisioning Service. Registration records are created automatically; they can be deleted, but they can't be updated.
 
 ## Registration ID
 
-The registration ID is used to uniquely identify a device registration with the Device Provisioning Service. The registration ID must be unique in the provisioning service [ID scope](#id-scope). Each device must have a registration ID. The registration ID is a case-insensitive string of alphanumeric characters plus the special characters: `'-'`, `'.'`, `'_'`, `':'`. The last character must be alphanumeric or dash (`'-'`). DPS supports registration IDs up to 128 characters long.
+The registration ID is used to uniquely identify a device registration with the Device Provisioning Service. The registration ID must be unique in the provisioning service ID scope. Each device must have a registration ID. The registration ID is a case-insensitive string of alphanumeric characters plus the special characters: `- . _ :`. The last character must be alphanumeric or dash (`-`). DPS supports registration IDs up to 128 characters long.
 
-* In the case of TPM, the registration ID is provided by the TPM itself.
-* In the case of X.509-based attestation, the registration ID is set to the subject common name (CN) of the device certificate. For this reason, the common name must adhere to the registration ID string format. However, the registration ID is limited to 64 characters because that's the maximum length of the subject common name in an X.509 certificate.
+* With TPM attestation, the registration ID is provided by the TPM itself.
+* With X.509-based attestation, the registration ID is set to the subject common name (CN) of the device certificate. For this reason, the common name must adhere to the registration ID string format. However, the registration ID is limited to 64 characters because that's the maximum length of the subject common name in an X.509 certificate.
 
 ## Device ID
 
-The device ID is the ID as it appears in IoT Hub. The desired device ID may be set in the enrollment entry, but it is not required to be set. Setting the desired device ID is only supported in individual enrollments. If no desired device ID is specified in the enrollment list, the registration ID is used as the device ID when registering the device. Learn more about [device IDs in IoT Hub](../iot-hub/iot-hub-devguide-identity-registry.md).
+The device ID is the ID as it appears in IoT Hub. The desired device ID may be set in the enrollment entry, but it isn't required to be set. Setting the desired device ID is only supported in individual enrollments. If no desired device ID is specified in the enrollment list, the registration ID is used as the device ID when registering the device. Learn more about [device IDs in IoT Hub](../iot-hub/iot-hub-devguide-identity-registry.md).
 
 ## Operations
 
-Operations are the billing unit of the Device Provisioning Service. One operation is the successful completion of one instruction to the service. Operations include device registrations and re-registrations; operations also include service-side changes such as adding enrollment list entries, and updating enrollment list entries.
+Operations are the billing unit of the Device Provisioning Service. One operation is the successful completion of one instruction to the service. Operations can include device registrations and re-registrations as well as service-side changes like adding and updating enrollment list entries.