TLS crypto method "NX_CRYPTO_NONE" issue

[Kim-Wurtz]

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We have since sometime during Fall 2023 not been able to connect our embedded devices, using the Azure RTOS / NetX Duo and ADU service, to connect to our IoTHub. They all fails during the initial TLS handshake. Up until sometime during the Fall 2023 they all worked without any issues, so clearly something has changed on the Azure IoTHub side.

I have narrowed the issue down to supported TLS crypto methods. During initialization of the ADU agent the function:

nx_azure_iot_hub_client_initialize(...)

is called where one of the parameters is:

_nx_azure_iot_tls_supported_crypto

which is a NX_CRYPTO_METHOD structure containing the supported crypto methods.

If this structure contains an entry defined as NX_CRYPTO_NONE the devices are not able to connect. If I remove this method from the crypto methods structure they are all then able to connect.

Is there anything we can do on the IoTHub side (configuration etc.) to have all our already deployed devices connect again, or is it expected behavior when one on the crypto methods is set to NX_CRYPTO_NONE?

As now they are all unreachable via ADU service for updating the firmware

They are all deployed with NetX Duo version 6.1.11