Bitcoin Optech #152: Lightning Node Funds And More

Bitcoin Optech #152: Lightning Node Payments And More

This week’s newsletter describes a LN node fee proposal, Bitcoin Core PR Review Club meeting and more.

This week’s newsletter describes a LN node fee proposal, Bitcoin Core PR Review Club meeting and more.

The Bitcoin Optech newsletter gives readers with a top-stage summary of the supreme technical files occurring in Bitcoin, along with resources that assist them be taught more. To assist our readers defend up-to-date with Bitcoin, we’re republishing the most fresh inconvenience of this newsletter below. Undergo in suggestions to subscribe to receive this assert straight to your inbox.

This week’s newsletter describes a proposal to allow LN nodes to receive funds without maintaining their non-public keys on-line the general time. Also incorporated are our unparalleled sections with the summary of a Bitcoin Core PR Review Club meeting, announcements of fresh tool releases and launch candidates, and descriptions of famous adjustments to trendy Bitcoin infrastructure tool.


  • Receiving LN funds with a mostly offline non-public key: in 2019, developer ZmnSCPxj proposed an substitute intention to encapsulate pending LN funds (HTLCs) that can within the cleave price of the quantity of community bandwidth and latency required to settle for a fee. More only within the near previous, Lloyd Fournier instructed the foundation could perchance perchance even be aged to allow a node to settle for more than one incoming LN funds without maintaining its non-public keys on-line. The root does maintain some downsides:
    • The node would quiet need its non-public keys to send a penalty transaction if significant.
    • The more funds the node bought without the employ of its non-public key, the more onchain charges would want to be paid if the channel turn out to be unilaterally closed.
    • The receiving node would lose privacy—its instant stare could perchance perchance be ready to uncover that it turn out to be the closing receiver of a fee and never accurate a routing hop. Nonetheless, for some waste-person nodes that don’t route funds, this could perchance perchance already be evident.
  • Within these obstacles, the foundation appears to be like workable and adaptations of it bought dialogue on the mailing list this week, with ZmnSCPxj preparing a transparent presentation. Fournier later instructed improvements to the foundation.

    Enforcing the foundation would require just a few essential LN protocol adjustments, so it appears to be like no longer at risk of be something customers could perchance perchance maintain uncover entry to to in both the short or medium timeframe. Nonetheless, somebody taking a evaluate to within the cleave price of the necessity for LN receiving nodes to decide on their keys on-line is impressed to analyze the foundation.

Bitcoin Core PR Review Club

In this monthly share, we summarize a newest Bitcoin Core PR Review Club meeting, highlighting one of the significant crucial questions and solutions. Click on a query below to appear at a summary of the retort from the meeting.

Prune g_chainman utilization in auxiliary modules is a refactoring PR (#21767) by Carl Dong that is share of a mission to de-globalize g_chainman as a first step in direction of modularizing the consensus engine. This could decouple ingredients and permit more centered attempting out. A longer-timeframe procedure is to utterly separate the consensus engine from non-consensus code.

The overview membership dialogue began with the next traditional questions ahead of diving deeper into the code adjustments:

  • This PR is a refactoring and could perchance perchance no longer commerce any practical behaviour. What are some ways we are in a position to envision that?

    Reviewing the code in moderation, running the assessments, adding take a look at protection, inserting asserts or custom logging, building with –allow-debug, running bitcoind with the adjustments, and stepping during the code with debuggers admire GDB or LLDB.
  • This PR is share of a smarter mission to modularize and separate the Bitcoin Core consensus engine. What are some advantages of doing that?

    This could perchance perchance construct it more straightforward to reason about, make a choice, configure and take a look at the code. It could perchance perchance perchance repeat a minimal API for security and maintainability, with configuration alternatives to budge non-global files. Shall we assign ingredients with variable parameters, providing more defend watch over over attempting out these objects with diverse configurations.
  • What is the ChainstateManager to blame for?

    The ChainstateManager class gives an interface for creating and interacting with one or two chainstates: preliminary block download (IBD) and an elective snapshot.
  • What does CChainState attain?

    The CChainState class stores the present handiest chain and gives an API to substitute our native knowledge of its narrate.
  • What is the CChain class?

    The CChain class is an in-memory indexed chain of blocks. It contains a vector of block index pointers.
  • What is the BlockManager to blame for?

    The BlockManager class maintains a tree of blocks stored in m_block_index that is consulted to bump into basically the most-work chain tip.
  • What is cs_main?

    cs_main is a mutex that protects validation-particular files (as well as, for now, many other things). The title intention severe share essential, as it safe files in essential.cpp, and the code that is now in validation.cpp and net_processing.cpp aged to be in one file called essential.cpp).
  • Conceptually, after we consult with the “validation” share of the codebase, what does that consist of?

    Validation stores and maintains our handiest peek of the block chain and connected UTXO narrate. It also involves an interface to put up unconfirmed transactions to the mempool.

Releases and launch candidates

New releases and launch candidates for trendy Bitcoin infrastructure tasks. Please defend in suggestions upgrading to fresh releases or serving to to take a look at launch candidates.

  • LND 0.13.0-beta.rc5 is a launch candidate that adds toughen for the employ of a pruned Bitcoin beefy node, permits receiving and sending funds the employ of Atomic MultiPath (AMP), and will enhance its PSBT capabilities, among other improvements and bug fixes.

Important code and documentation adjustments

Important adjustments this week in Bitcoin Core, C-Lightning, Eclair, LND, Rust-Lightning, libsecp256k1, Hardware Pockets Interface (HWI), Rust Bitcoin, BTCPay Server, Bitcoin Improvement Proposals (BIPs), and Lightning BOLTs.

  • Bitcoin Core #22051 adds toughen for importing descriptors for taproot outputs into the Bitcoin Core wallet. This PR permits wallet customers to receive funds to taproot outputs and is the prerequisite for an launch PR that implements beefy toughen for customers to receive to and exercise from taproot outputs.
  • Bitcoin Core #22050 drops toughen for version 2 Tor onion products and providers (hidden products and providers). Version 2 products and providers are already deprecated and the Tor mission has launched that they’ll change into inaccessible in September. Bitcoin Core already helps version 3 onion products and providers (gawk Newsletter #132).
  • Bitcoin Core #22095 adds a take a look at to appear at how Bitcoin Core derives BIP32 non-public keys. Though Bitcoin Core has constantly derived these keys correctly, it turn out to be only within the near previous found that some other wallets had been incorrectly deriving a bit of of more than 1 out of 128 keys by failing to pad extended non-public keys (xprivs) that had been no longer as a lot as 32 bytes lengthy. This doesn’t directly waste in a loss of funds or a cleave price in security, then again it does create problems for customers who create an HD wallet seed in one wallet and import it into one other wallet or who create multisignature wallets. The take a look at vector implemented on this PR will seemingly be being added to BIP32 to assist future wallet authors steer clear of this inconvenience.
  • C-Lightning #4532 adds experimental toughen for upgrading a channel—rebuilding the most fresh commitment transaction so that it could perchance most likely perchance perchance incorporate fresh aspects or structural adjustments, e.g. converting to the employ of taproot. The protocol begins with a demand for quiescence, an settlement that neither birthday party will send any fresh narrate updates until the quiescence length is performed. All the intention through this period, the nodes negotiate the adjustments they wish to construct and implement them. Finally, the channel is restored to beefy operation. C-Lightning within the indicate time implements this within the center of connection reestablishment when the channel has already been in a length of compelled inactivity. Varied proposals for channel upgrades had been discussed in Newsletter #108 and the author of this PR wants the characteristic in share to work on the “simplified HTLC negotiation” described in Newsletter #109. This particular PR permits upgrading venerable channels to toughen option_static_remotekey, which C-Lightning first added toughen for in 2019, gawk Newsletter #64.
  • LND #5336 adds the skill for customers to reuse AMP invoices non-interactively by specifying a brand fresh fee secret. The default bill expiry for AMP invoices created by LND will seemingly be bumped to 30 days in negate to facilitate the aforementioned reuse mechanism.
  • BTCPay Server #2474 adds the skill to take a look at webhooks by sending inaccurate events that uncover all their usual fields nonetheless dummy files. This mirrors attempting out aspects on hand on centrally hosted Bitcoin fee processors equivalent to Stripe and Coinbase Commerce.

Gather the long-established put up here.

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