Bitcoin full node via Electrum Server 🌕

[matejzak]

Design: to be added
Spec: Notion

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Tech Spec

Main objective

Add support into blockchain-link for Electrum Server. This way the user will have the ability to opt-out from our Blockbook backends and set Electrum server address which they may have running on their personal Bitcoin node. Note that we will support Bitcoin only (no altcoins).

Blockchain-link

As mentioned the main part of this task is to add a new backend to blockchain-link. We will either add a new dependency that @prusnak listed below or write it ourselves. I have a small preference to write it ourselves because a) we want to be careful about adding new dependencies b) the projects do not seem very well maintained. I believe the best approach is to get inspired heavily by the libs (if the license allows it) but have it in the blockchain-link directly. But the decision is yours.

CLI option

We should also not forget about adding a CLI option to launch Suite against the Electrum server directly, otherwise some info might leak to our blockbooks once Suite is started. This needs to be discussed as it might not be needed after #3729?

Modify Bitcoin settings

User wishing to set their own Electrum server will go to Settings -> Coins -> Bitcoin's Advanced settings where they will be able to replace Blockbook URL with an Electrum server. @matejzak will prepare design for this.

Useful links

• There are number of public Electrum servers. For example listed here.
• I have personally tried electrum.blockstream.info:50002:s. If you would like to run Electrum against such server you can do that by running electrum --oneserver --server="electrum.blockstream.info:50002:s".

Next steps

• Prepare design for settings
• Discuss support in blockchain-link
• Add support to blockchain-link
• Document support in blockchain-link
• Add CLI option (if agreed upon)
• Add the option to settings
• Document the feature as a whole

[prusnak]

Is this an issue covering adding an option to use custom full node (instead of nodes of Satoshi Labs)?

You can already use custom node when you run Blockbook.

This issue is about possibility to connect to Bitcoin Core directly (or at least to Electrum server, which has lower system requirements than Blockbook)

[josibake]

Do you have a high level idea on how this will work? specifically, I am running a full node on a raspi with electRS and use electrum desktop as my wallet, connected to my full node. I'd like to use Trezor Suite instead and I'm hoping I can keep the same full node setup and just point Trezor Suite at it once this is implemented.

[prusnak]

We are evaluating this and it indeed seems that connecting to Electrum API is probably the best way forward as this is what most of people have in mind when they say "full node".

Electrum APIs in JS:

• https://www.npmjs.com/package/electrumjs (inactive)
• https://www.npmjs.com/package/electrum-client (inactive)
• https://www.npmjs.com/package/@codewarriorr/electrum-client-js (active)
• https://github.com/BlueWallet/rn-electrum-client (active)
• https://github.com/janoside/electrum-client (active)

[samuel-emrys]

@prusnak for what it's worth, I'd be interested in integration with bitcoin core more than electrum.

[tsusanka]

@prusnak feel free to check my Tech Spec draft in the original post.

[prusnak]

Unfortunately without pagination there's no way to actually measure progress.

Progress does not have to be a progress bar with percent. Progress can be shown also as a rotating wheel or just a text "please wait, I am doing something" :-)

[tsusanka]

We have discussed next steps with @marekrjpolak in more detail:

Product (@matejzak):

• Create design for Settings - option to add Electrum server (maybe it is the same input as the one for blockbook 🤷)
• Improve onboarding - option for connecting Electrum server (nice to have, we can roll this out without this as we'll have the CLI --option)
• Check and finalise design for "modal loading"
• Create design for signalising that we are using custom backend in the upper menu (similar to how we display that you are using Tor). Note that this might have three states: 1. fully on our blockbook servers 2. fully on custom servers 3. mix of 1 and 2 (using Bitcoin via Electrum server but other coins via our blockbook instances).

Code (@marekrjpolak):

• Add support for Taproot
• Send info to @matejzak what kind of info we may show in the loader
• Check what we are caching but let's not worry about advanced caching to files (cache only during runtime)
• Discuss Coingecko vs Blockbook:
  • There is a small problem with fetching (historic) fiat rates. We have replaced Blockbook with Electrum server so we do not have the needed data. There are two options:
    1. Hide historic fiat rates and use Coingecko for these users. Note that this has huge implications into the design such as hiding the dashboard, some tool tips etc.
    2. Extrapolate the "fiat rates" logic from blockchain-link into separate module/package/whatever and get fiat rates from Blockbook. This is probably the right solution, although a bit more time consuming.

.. and review obviously.

[Kixunil]

FYI regarding Electrum servers Taproot should be no-op because the Electrum protocol already hashes whole script_verify and doesn't care what's inside.

[tsusanka]

Btw some numbers from testing this on the PR (commit 5348af3) on my "small testing seed" (cca 10 transactions):

• About 12 seconds from choosing Standard wallet to the dashboard loaded up properly on our internal company server. Tor OFF.
• About 22 seconds from choosing Standard wallet to the dashboard loaded up properly on my personal raspberry pi running Umbrel. Tor OFF.
• About 33 seconds from choosing Standard wallet to the dashboard loaded up properly on my personal raspberry pi running Umbrel. Tor ON.

[tsusanka]

Discuss Coingecko vs Blockbook:

To recap this: we will keep communicating with Blockbook for fiat rates and we will extend this blockbook REST endpoint with batching option. @martinboehm will look into it, it should be an easy one :).

[tsusanka]

Some product work still needs to be done.

[bosomt]

Can you please add update of context help in Sessings/Crypro to tasks/next steps ?

[hynek-jina]

Follow-up issues are tracked in separate Milestone

[tsusanka]

Wooohooo, great job everyone 🎉 🎉 🎉 .