Add Export XPUB Option for BULL Wallet

[thibistaken]

Currently, there's no export preset option for the FOSS BULL wallet, developed by Bull Bitcoin. It would be good to add it as BULL now supports Seed Signer as a hardware device.

h/t for @SovereignGG who first tested the feature on BULL 🥇

[BullishNode]

Is it possible to get descriptor instead of xpub?

The ideal flow here would be segwit descriptor straight to QR code

[kdmukai]

@BullishNode what QR format(s) do you support? @newtonick is the expert, but I believe we also already support the UR:ACCOUNT format which, to my understanding, is a much richer export.

@thibistaken one of our TODO items is to re-review the formats currently being used by the supporting wallet software out there. Our current approach of listing specific wallets just won't scale over time. And most likely there are only 2-3 QR formats being used and odds are that they'll start converging over time down to just one or two. We've talked about changing the UX flow to just assume the most common format and then provide instructions for the user to be able to swap formats if the default can't be read by the software they're using.

[BullishNode]

We support URQR and BBQR both

cc @ethicnology

[SovereignGG]

@kdmukai FYI, I was able it to connect the SeedSigner to BULL Wallet via Nunchuk Xpub export, but not the BlueWallet option.

However, once I connect the SS via Nunchuk, the wallet doesn't automatically appear in on the Home screen of the mobile app, like it does for other HHW which get connected. But you need to close and reopen the BULL app and the Seedsigner wallet will show up.

[ethicnology]

We support single signature descriptors (bip44/bip49/bip84) formatted:

• combined https://github.com/ethicnology/dart-satoshifier/blob/ad386bc15717532aa5dc8e349ba12d22a89f8550/lib/_test_value.dart#L41
• external https://github.com/ethicnology/dart-satoshifier/blob/ad386bc15717532aa5dc8e349ba12d22a89f8550/test/descriptor_test.dart#L371

The payload is not big so we can use a plain text QR.

EDIT: We also support this kind of key expression [origin]xpub https://github.com/ethicnology/dart-satoshifier/blob/ad386bc15717532aa5dc8e349ba12d22a89f8550/test/descriptor_test.dart#L296

[SovereignGG]

@kdmukai quick update, on the latest version of BULL Wallet version 6.2.3+107 the 'Nunchuk' Export Xpub works perfect now. (no more need to restart the wallet app for it to be visible.)

Could you duplicate the Nunchuk export and name it BULL. That's should be all.

[kdmukai]

Could you duplicate the Nunchuk export and name it BULL. That's should be all.

This is exactly the functionality I'm trying to avoid going forward.

We currently list five wallet software but only actually have three paths:

        if coordinator == SettingsConstants.COORDINATOR__SPECTER_DESKTOP:
            self.qr_encoder = SpecterXPubQrEncoder(**encoder_args)

        elif coordinator in [SettingsConstants.COORDINATOR__BLUE_WALLET,
                             SettingsConstants.COORDINATOR__KEEPER]:
            self.qr_encoder = StaticXpubQrEncoder(**encoder_args)

        else:
            self.qr_encoder = UrXpubQrEncoder(**encoder_args)

Sparrow and Nunchuk land in that final else. Bull would as well.

Notice also that Sparrow, Nunchuk, and now Bull are likely to be the most actively developed wallets going forward. So it feels like we already are starting to see that possible convergence I mentioned above.

Specter Desktop can either be dropped or we can urge that team to add support for the converging format.

Blue Wallet... maybe we can PR in support.

And I'm not sure Keeper will be a consideration going forward.

Realistically we're still a few months away from our next release. I think cleaning house in this area should be our priority vs continuing with the status quo.

[SovereignGG]

Ok that makes sense. In that case for the time being, as we need to create instructions and tutorials for all the other hardware wallets, for SeedSigner integration we will just use the 'Sparrow' Xpub export version, as it's not working on BULL version 6.2.3+107.

And once the next SeedSigner version is released in the next few months, we will update our guide / instructions according to the new export procedure.