SAS token mismatch on Azure DPS with Azure IoT Edge

Question

Hi,

I have a recent issue with DPS registration requests, giving me error " {"Message":"{"errorCode":401002,"message":"The specified SAS token has an invalid signature. It does not match either the primary or secondary key.","trackingId":"E377D48366F943E189A5FEA744D89D95-G2:-TimeStamp:2025-01-03T14:15:03.453324531Z","timestampUtc":"2025-01-03T14:15:03.453324531Z","info":null}","ExceptionMessage":""}".

I have two different IoT Hub in different environments, and my devices are running IoT Edge with group enrollments symmetric keys, but Azure Identidy daemon seems to only be able to register in one of the DPS environments. For this other one, I have that error. I already tried to regenerate the keys. It has been working for many months now, but all of a sudden it doesn't work anymore in that environment. And I can't remember changing anything in the setup.

Answer 1

Hello @LALANNE Jeremie - CELLENZA ,

welcome to this moderated Azure community forum.

You say you have multiple DPS environments (as in '... one of the DPS environments')?

Your Azure IoT Edge runtime can only connect to one Device Provisioning service where the right IoT Hub will be selected/linked to your device.

Please check this blog post with background information about the group enrollments using symmetric keys.

There you find details on how to generate the right unique registration ID for each device.

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Answer 2

To whoever comes by that same issue, I figured out (with the help of Azure support) that the issue came from the DPS linked iot hub not being synced correctly with that iot hub. When the DPS is linked to iot hub, the link is not synchronous. When the link is created, it takes the connection string of the iot hub with the specified shared access policy, and that's it. At some point we renewed the primary key of the iot hub, and broke that link.

The solution was to remove and readd the dps link to the iot hub.
The other solutin with Azure CLI is az iot dps update --name MyExampleDps --set properties.iotHubs[0].connectionString="HostName=MyExampleHub-2.azure-devices.net;SharedAccessKeyName=iothubowner;SharedAccessKey=NewTokenValue"
(Take from documentation https://learn.microsoft.com/en-us/azure/iot-dps/how-to-manage-linked-iot-hubs?tabs=cli#update-keys-for-linked-iot-hubs)