Use serialization helpers

[robin-nitrokey]

Instead of using Trussed’s re-exports of postcard that will be removed in Trussed 0.2.0, we use the public and stable serialization helper methods.

[sosthene-nitrokey]

Actually we should use trussed_rsa_alloc::RsaPublicParts::(de)serialize rather than postcard directly. Maybe even trussed-rsa-alloc could wrap the RsaPublicParts in a newtype to hide the serde implementation.

[robin-nitrokey]

This is already done by this PR (that’s what I meant with “use the public wrapper”). But there is no matching mechanism for the private key injection AFAIS so we have to use postcard there.

[sosthene-nitrokey]

https://github.com/Nitrokey/trussed-rsa-backend/blob/main/src/types.rs#L79 ?

[robin-nitrokey]

Ah, must have missed that. Updated.

[sosthene-nitrokey]

Why didn't the pipeline run?

[robin-nitrokey]

I think it ran (Pipeline #19494) but the checkmarks are missing.

[sosthene-nitrokey]

I triggered it manually

[robin-nitrokey]

Yes, but there’s also a pipeline that was triggered by sync-github.