Combined summary - On the scalability issues of onboarding millions of LN mobile clients
The Bitcoin development community has engaged in extensive discussions addressing technological challenges and potential solutions to enhance the security, usability, and decentralization of Bitcoin and the Lightning Network (LN).
Keagan McClelland emphasized the need for easier connections between mobile Lightning clients and personal full nodes to counter centralized services. Christopher Allen introduced QuickConnect for secure remote node connections via Tor v3, supported by various tools and hardware, and requested contributions on GitHub for further development.
Nodes' economic significance is recognized as a defense against miner consensus hijacks, with hopes that LN will provide cheaper transactions while maintaining noncustodiality. Suggestions include selecting backup nodes during client initialization and considering private servers for robust Simplified Payment Verification (SPV).
Challenges in user experience, such as installation, configuration, and understanding client-server distinctions, were noted. Will from the mailing list detailed his setup and acknowledged areas for improvement such as backups and liquidity. Start9 Labs identified zero-configuration apps and clear guides as possible solutions.
Security discussions revolved around trusting full nodes for SPV security, employing header chains for transaction validation, and implications of wide LN adoption without full node verification, including the risks of a split into full-node-coin and SPV-coin due to miners targeting SPV wallets. Antoine Riard and Chris Belcher suggested incentivizing diverse backup servers to prevent centralization.
Luke Dashjr and Lloyd Fournier underscored operating full nodes for Bitcoin's security model, warning against attacks exploiting SPVs' trust issues. Off-grid nodes securely obtaining blockchain data through a system resembling watchtowers was proposed by ZmnSCPxj.
Christopher Allen called for collaborators to define wallet functionality levels and enhance core wallet features, advocating for a cryptographic capability mechanism to restrict RPC functionality exposure in Bitcoin-core. FullyNoded2 multisig wallet serves as an example of secure communication between personal nodes and users.
Antoine Riard and Igor Cota explored running full nodes on mobile devices with Sleeper Nodes™, storing blocks when idle. However, concerns remain about scalability, security, and privacy, with suggestions for monetizing node operation like servicing filters within a watchtower-like framework.
McClelland critiqued Bitcoin Core's RPC interface, proposing three distinct ports to reduce security risks. Blockchain Commons expressed interest in hosting proposals for wallet functionalities. BIP 157's stateless nature was discussed, with concerns over network demand but recognition of its potential for serving light clients over HTTP.
Developers contemplate alternative networks for supporting light clients and increasing full node diversity, such as geostationary satellites or radio systems. The security model faces "consensus capture" risks, with strategies including allowing light clients to choose their full node tethers.
The overarching theme is finding a balance between light client usability and a decentralized, secure Bitcoin network. While protocols like BIP 157 and economic incentives for full-node operation are proposed, there are warnings against undermining Bitcoin's trust-minimization principles. Additionally, the risks of malicious servers providing incorrect data to light clients and LN's vulnerabilities due to its liveliness requirements were discussed. Compensation for serving filters may address light clients' free-riding problem, fitting into the broader paradigm of delegated protocol execution.