Subject: [Suit] Feedback/ comments on moran-suit-architecture

From: Madjid Nakhjiri <[email-masked]>
Date: Fri, 10 Nov 2017 22:35:31 +0000

Hi all, suit-architecture authors

I reviewed the draft and have some comments. I had originally embedded the comments in a txt file and sent to Hannes, but he asked to send to the list and I am assuming the list does not accept attachment, so here it is. Sorry for the long-winded list.

Introduction:
I wonder if 3rd use case is "Augmenting uninitiated devices with provisioning and configuration data from service operators"

Section 3.2 on broadcast delivery not relying on transport security. True and it should be pointed out:
integrity or confidentiality protection mechanisms should be applied during image preparation and later installation process, instead. The same applies for requirements regarding authorization for receiving the update by devices.
Note: I am wondering what the use case for FW update broadcast in true sense is?

Section 3.3 regarding "the information that is encrypted individually for each device must be an absolute
   minimum."
This is hard to meet if the entire firmware image has to be protected.

Regarding "All information necessary for a device to make a decision about the
   installation of an update must fit into the available RAM of a
   constrained IoT device.  This prevents flash write exhaustion."

I am not clear on this ,if I hash the entire image and sign the hash, what is "all information necessary" in that case?
Are we saying all image has to fit in the RAM when the hash is being calculated? What if it resides on external flash?

Section 3.4
To be added IMO: download/distribution servers shall properly log information on download operation along with relevant metadata, such as device identity, FW metadata (manifest), result of download. Access to the logs shall be protected through proper IAM mechanisms.

Section 6
Manifest should include "signing time" and version of image, so it can readily be available for distribution servers w/o having to parse the image before sending..

Regards,
Madjid Nakhjiri,
Sr. Director, ARTIK Security Architect