Re: [Suit] SUIT Manifest MTI Algorithms

[Michael Richardson <[e-mail]>]

Emmanuel Baccelli <[e-mail]> wrote:
    > We have recently conducted an experimental study on this topic,
    > evaluating SUIT on common microcontrollers (Cortex-M, ESP-32 and
    > RISC-V) In particular, we evaluate the cost of upgrading from ed25519
    > to HSS/LMS with SUIT used to secure actual RIOT firmware updates: see
    > preprint at https://eprint.iacr.org/2021/781.pdf

Awesome!

    > In a nutshell: for small-sized software updates using SUIT with LMS, we
    > measured impact on network transfer costs (~45% more data over the
    > wire) and on memory footprint on-device (~35% more Flash memory
    > required), but only little impact on RAM or execution time, compared to
    > using SUIT with ed25519. If the baseline is something else (i.e. not
    > SUIT, or not ed25519), the overhead might be more.

I looked into your paper trying to understand where this 35% more flash
memory required.  Is it table 6 and 7?   I think it's a 35% increase of
the verification code from ECDSA to HSS-LSS.  I don't think it's a 35%
increase in total flash required, right?

    > What will be considered bearable overhead to upgrade to SUIT-compliant
    > security, on microcontroller-based IoT devices? That is a question.

Your paper seems to suggest it's acceptable.

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