Re: DTLS over CoAP for the Zephyr project

Lubos, Robert

Yes, applying `overlay-802154.conf` will make the sample use Zephyr’s native 6lowpan stack. Applying ` overlay-ot.conf` will make the sample use OpenThread, which implements it’s own 6lowpan layer. You can also combine two overlays – `-DOVERLAY_CONFIG=”overlay-802154.conf overlay-tls.conf”` to run DTLS over 802.15.4 6lowpan. Combining DTLS with OpenThread is not supported at this moment.


Certificates are also supported with DTLS sockets – echo_client/echo_server use them to secure DTLS connection. The lwm2m_client though indeed uses PSK.


nrf52840_pca10056 has a hardware crypto acceleration module – CryptoCell 310, which is capable of accelerating ECC operations (we use it for example in “vanilla” OpenThread repository). We have some support for it in our Zephyr based SDK (, sadly we haven’t integrated and tested it with networking samples yet.





From: users@... [mailto:users@...] On Behalf Of Nikos Karamolegkos via Lists.Zephyrproject.Org
Sent: Thursday, July 25, 2019 12:12
To: users@...
Cc: users@...
Subject: Re: [Zephyr-users] DTLS over CoAP for the Zephyr project


Once again thank you for your detailed answer. Therefore, If I apply the "overlay-802154.conf" overlay config then I will have the 6lowpan stack?

Yes, the OpenThread is really a nice choice.

Also, I am going to check the module nrf52840_pca10056 although doesn't support hardware acceleration as I can see. I would like to find a module which can support hardware acceleration for ECC in DTLS (not only pre-shared key). For now, as I can see in the tls_credential.h file the DTLS is using pre-shared key (PSK) only.



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