feat: example using hwi signing with

[sdmg15]

Description

Integrates a new BDK signer using async-hwi.
The included example uses Bitbox02 but can be easily extended to use any other supported device.

Notes for reviewer

It's related to issue #20

Changelog notice

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

[notmandatory]

Thanks for this! looks like a good simple example for using hwi-async with bdk_wallet. One FYI we are talking about removing signing from bdk_wallet and delegating it to the rust-bitcoin Psbt::sign function. How hard would it be to use hwi-async to just sign a Psbt ?

[sdmg15]

async-hwi provides a function with the following signature

    async fn sign_tx(&self, tx: &mut Psbt) -> Result<(), Error>;

So I think after constructing the psbt we can just call that function and voila.

[sdmg15]

So at this level we can just call bibox_signer.sign(psbt) given that the psbt has been constructed with bdk_wallet or something else

[notmandatory]

Yes I think this is the right approach. Even though it makes the example much simpler it's still useful to show the end-to-end flow of using async-hwi to sign a psbt created with bdk_wallet::TxBuilder (and eventually the bdk_tx::TxBuilder).

[sdmg15]

Is it a good idea to add syncing wallet code in the example?
If not what's a good way of mocking the wallet with some utxos to sign?

[sdmg15]

@notmandatory
Instead of syncing I "mocked" the wallet with some UTXOs since syncing isn't the goal of this example.

I also added a feature simulator when enabled for people that don't have a physical device connected but still want to run the example (Still need to add instructions on the readme on how to run)

Please let me know what you think

[oleonardolima]

Thanks for working on this one, I left a few comments and also would recommend squashing the commits into a single one and follow the https://www.conventionalcommits.org/en/v1.0.0/ (e.g chore(example): add example using `async-hwi`.

[oleonardolima]

You probably can have this as an optional dependency with the simulator feature.

[oleonardolima]

It looks like they already have this patched in the official release v0.8.0, we should be using that instead.

[sdmg15]

Yes indeed I was the one that requested the fix 😉 . But it's not needed anymore. The initial way I understood what we wanted was not right.

[oleonardolima]

Suggested change

	`$ cargo run `
	`$ cargo run --bin example_wallet_hwi_signer`

[oleonardolima]

Suggested change

	cargo run --features=simulator
	cargo run --bin example_wallet_hwi_signer --features=simulator

[oleonardolima]

As the example is focused on a BitBox device, we probably should also explicitly use only the bitbox feature.

[sdmg15]

Thanks for taking a look @oleonardolima. I've addressed your suggestions.