Injecting public keys into FTDs for FIT verification

Jan Kiszka jan.kiszka at
Fri Nov 5 13:42:09 CET 2021

On 05.11.21 11:28, Rasmus Villemoes wrote:
> On 05/11/2021 11.16, Jan Kiszka wrote:
>> Hi all,
>> in order to use CONFIG_FIT_SIGNATURE and also
>> CONFIG_SPL_FIT_SIGNATURE, a public key needs to be placed into the
>> control FDT. So far, I only found mkimage being able to do that during
>> FIT image signing. That is fairly unhandy and often incompatible with
>> how firmware is built & signed vs. how the lifecycle of the artifacts to
>> be loaded and verified look like. Is there really no other way than
>> mkimage -K?
>> I'm currently considering to derive a tool that, given a public key
>> (which is easy to hand around, compared to the private key needed for
>> signing), injects them into a FDT. Then I would hook that up as generic
>> feature for U-Boot builds, enriching all control FTDs already during the
>> first build with this when requested.
>> Am I missing an even simpler approach?
> You're not missing an existing upstream simpler approach, but it's
> certainly an itch that others have had [1] [2]. My latest attempt
> does now have an R-b by Simon, so now I'm just waiting for that to
> actually make it into master. I have the script(s) that will convert a
> public key to a .dtsi fragment, and I'm happy to share that.

Cool, that would be very welcome!


> Rasmus
> [1]
> [2]

Siemens AG, T RDA IOT
Corporate Competence Center Embedded Linux

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