TLS support in Azure IoT Hub Device Provisioning Service (DPS)

DPS uses Transport Layer Security (TLS) to secure connections from IoT devices.

Current TLS protocol versions supported by DPS are:

  • TLS 1.2

TLS 1.0 and 1.1 are considered legacy and are planned for deprecation. For more information, see Deprecating TLS 1.0 and 1.1 for IoT Hub.

Restrict connections to TLS 1.2

For added security, it is advised to configure your DPS instances to only allow device client connections that use TLS version 1.2 and to enforce the use of recommended ciphers.

To do this, provision a new DPS resource setting the minTlsVersion property to 1.2 in your Azure Resource Manager template's DPS resource specification. The following example template JSON specifies the minTlsVersion property for a new DPS instance.

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "resources": [
        {
            "type": "Microsoft.Devices/ProvisioningServices",
            "apiVersion": "2020-01-01",
            "name": "<provide-a-valid-DPS-resource-name>",
            "location": "<any-region>",
            "properties": {
                "minTlsVersion": "1.2"
            },
            "sku": {
                "name": "S1",
                "capacity": 1
            },
        }     
    ]
}

You can deploy the template with the following Azure CLI command.

az deployment group create -g <your resource group name> --template-file template.json

For more information on creating DPS resources with Resource Manager templates, see, Set up DPS with an Azure Resource Manager template.

The DPS resource created using this configuration will refuse devices that attempt to connect using TLS versions 1.0 and 1.1. Similarly, the TLS handshake will be refused if the device client's HELLO message does not list any of the recommended ciphers.

Note

The minTlsVersion property is read-only and cannot be changed once your DPS resource is created. It is therefore essential that you properly test and validate that all your IoT devices are compatible with TLS 1.2 and the recommended ciphers in advance.

Note

Upon failovers, the minTlsVersion property of your DPS will remain effective in the geo-paired region post-failover.

DPS instances that are configured to accept only TLS 1.2 will also enforce the use of the following cipher suites:

Recommended TLS 1.2 cipher suites
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256

Legacy cipher suites

These cipher suites are currently still supported by DPS but will be depreciated. Use the recommended cipher suites above if possible.

Option #1 (better security)
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P384 (uses SHA-1)
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P256 (uses SHA-1)
TLS_RSA_WITH_AES_256_GCM_SHA384 (lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_128_GCM_SHA256 (lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_256_CBC_SHA256 (lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_128_CBC_SHA256 (lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_256_CBC_SHA (uses SHA-1, lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_128_CBC_SHA (uses SHA-1, lack of Perfect Forward Secrecy)
Option #2 (better performance)
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P256 (uses SHA-1)
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P384 (uses SHA-1)
TLS_RSA_WITH_AES_128_GCM_SHA256 (lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_256_GCM_SHA384 (lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_128_CBC_SHA256 (lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_256_CBC_SHA256 (lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_128_CBC_SHA (uses SHA-1, lack of Perfect Forward Secrecy)
TLS_RSA_WITH_AES_256_CBC_SHA (uses SHA-1, lack of Perfect Forward Secrecy)

Use TLS 1.2 in the IoT SDKs

Use the links below to configure TLS 1.2 and allowed ciphers in the Azure IoT client SDKs.

Language Versions supporting TLS 1.2 Documentation
C Tag 2019-12-11 or newer Link
Python Version 2.0.0 or newer Link
C# Version 1.21.4 or newer Link
Java Version 1.19.0 or newer Link
NodeJS Version 1.12.2 or newer Link

Use TLS 1.2 with IoT Hub

IoT Hub can be configured to use TLS 1.2 when communicating with devices. For more information, see Deprecating TLS 1.0 and 1.1 for IoT Hub.

Use TLS 1.2 with IoT Edge

IoT Edge devices can be configured to use TLS 1.2 when communicating with IoT Hub and DPS. For more information, see the IoT Edge documentation page.