GPG-split like application

[Martin Holst Swende]

Hi,

I would like to create an application that behaves very similar to how
the GPG split works. I am developing a 'signer' for Ethereum
(https://github.com/holiman/go-ethereum/tree/signer_mhs/cmd/signer),
which is basically a wallet.

The signer exposes an external API, which can be either RPC-based or
HTTP-based. The external API is considered untrusted, and all requests
to that API are handled via sign-what-you-see on the 'internal' side via
a UI of the users choice. The user can either start the signer with a
native CLI ui, or use a GUI to start the signer (in the trusted
environment), e.g the proof-of-concept QT-based poc implementation at
https://github.com/holiman/qtsigner.

Now, I would like to use a similar mechanism as gpg-split uses, in order
to have the signer running in a separate 'vault' which does not have
external networking, but does expose either RPC or HTTP to other VM:s.

So I'm curious about the different options that exist for implementing
this, and if anyone can point me towards what resources I should read up
on to understand what I need to do to accomplish this. Do I need to
build a modified Qubes in order to put this together, or is it enough to
allow RPC interaction via rules?

Cheers,

Martin Holst Swende

[Raffaele Florio]

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> So I'm curious about the different options that exist for implementing this, and if anyone can point me towards what resources I should read up on to understand what I need to do to accomplish this. Do I need to build a modified Qubes in order to put this together, or is it enough to allow RPC interaction via rules?

The best way is to use [0]. It's here for this purpose. So you need to write a server side software, a client side software and the policies. Essentially the server side software acts like an adapter for the wallet (you don't need either to modify the wallet's code).
HTTP isn't a good idea for various reasons:
- - *more* complexity
- - 'signer' VM exposed to other VMs
- - absence of Qubes OS RPC policy
- - absence of OS's integration and so on...

[0] = https://www.qubes-os.org/doc/qrexec3/

Best Regards,
Raffaele.
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