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by nothasan 1293 days ago
Off-topic but what do you think they used here to render the UI. Qt?
2 comments
the__alchemist 1293 days ago
The correct play is writing to the display buffer directly using a thin wrapper that has fonts, drawing primitives etc. I hope they don't have a GPOS and Qt on this.
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popol12 1293 days ago
home made framework like the previous devices, I'd say. The UI is running directly in the secure element (~1.5MB flash, ~50kb ram) so it's very memory constrained.
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lxgr 1293 days ago
I'd be really surprised if they can pull that off. My guess is on a two-chip architecture [1] like for the original Nano S (non-plus).

[1] https://developers.ledger.com/docs/nano-app/bolos-hardware-a...

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popol12 1293 days ago
They already pulled it off for their previous device, the Nano X (and S+, which shares the same secure element with the new Stax device)
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lxgr 1293 days ago
The Nano X has a minimal user interface and two buttons. I really doubt the Stax can be driven by only a secure element like that.
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popol12 1292 days ago
I just asked a guy working there, he confirmed that the screen and the touch inputs are solely driven by the SE. Basically the OS only stores a few fonts and all the graphical shapes are rebuild at runtime, it's a time for space trade-off.
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lxgr 1292 days ago
Wow, and all that runs on the SE? That would be really impressive!

It's still not ideal though, given that every additional feature or library blows up the trusted code base and increases the scope of any audit as a result.

Well, I just hope the existing wallets will remain supported going forward.

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