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Section 20 · Advanced

Protocol Improvements & Research

Research

⏱ Estimated reading time: 15 minutes

Current BIPs under discussion. Proposed protocol improvements. Taproot and recent upgrades. Scaling research. Privacy improvements. Covenant proposals.

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Taproot: Bitcoin's 2021 Privacy and Efficiency Upgrade

Taproot, activated in November 2021 at block 709,632, is Bitcoin's most significant protocol upgrade since SegWit in 2017. It combines three BIPs (340, 341, 342) to deliver Schnorr signatures, Merkelised Abstract Syntax Trees (MAST), and Tapscript — together improving Bitcoin's privacy, efficiency, and scripting flexibility in ways that will take years to fully leverage.

The Three Components

  • BIP 340 — Schnorr Signatures: Replaces ECDSA for Taproot outputs. Enables signature aggregation (MuSig), has cleaner security proofs, and is slightly more efficient.
  • BIP 341 — Taproot: The core upgrade. A Taproot output commits to both a key path (simple single-key or MuSig spend) and a script tree (arbitrary spending conditions). On-chain, a cooperative key-path spend is indistinguishable from a simple payment — regardless of the underlying script complexity.
  • BIP 342 — Tapscript: Updated scripting language for Taproot script paths; enables future soft forks to add new OP_CODEs more cleanly.

The Evolution of Bitcoin Transactions

Legacy (Pre-2017) Tx Data (Inputs & Outputs) Signatures (Inside Tx Block) Subject to Malleability SegWit (2017) Base Tx (1MB limit) Tx Data Witness Data Signatures Segregated Fixes Malleability Taproot (2021) Base Tx Tx Data Taproot Witness Schnorr + MAST Complex Logic Looks Simple SegWit separated signatures from transaction data to fix malleability and improve block capacity. Taproot upgraded the witness structure to make complex smart contracts indistinguishable from regular payments.

Why Taproot Matters for Privacy

Before Taproot: a 2-of-3 multisig transaction looked obviously different on-chain from a single-key transaction. After Taproot: if all signers cooperate, any Taproot output — whether backed by multisig, Lightning, a complex time-locked vault, or a simple key — looks identical on-chain. Cooperative transactions reveal nothing about their underlying conditions. This significantly improves privacy for Lightning channels, multisig wallets, and more.

"Taproot is not just one upgrade — it's a platform for the next decade of Bitcoin improvements. Many of the most exciting Bitcoin proposals build directly on Taproot." — Bitcoin developer community

Want to go deeper?

This content is written and approved by Marius, AI-assisted using Claude (Anthropic), with references curated from: Jameson Lopp (lopp.net, PD) · Mastering the Lightning Network (CC BY-SA 4.0) · Bitcoin Optech (bitcoinops.org, PD) · Lightning BOLTs (CC BY 4.0) · BIP341-342 Taproot specs (BSD).

Bitcoin Covenants: The Research Frontier of Bitcoin Programmability

A covenant is a restriction on how bitcoin can be spent not just now, but in future transactions. Standard Bitcoin scripting controls who can spend an output and when — but it cannot restrict what happens to the bitcoin after it's spent. Covenants change this: they allow encoding rules that "follow the coins" through subsequent transactions. This opens up powerful new capabilities — and significant debate about what Bitcoin should be able to do.

What Covenants Enable

  • Vaults: Time-delayed recovery. Send bitcoin to a vault; withdrawals are delayed, allowing the owner to cancel a theft attempt.
  • Payment pools: Multiple users share one UTXO, can exit individually — reduces on-chain footprint significantly.
  • Drivechain-style sidechains: Two-way pegs between Bitcoin and sidechains with improved security.
  • Inheritance automation: "If I don't move these coins for 1 year, allow heir to claim them."

Covenant Proposals Being Researched

  • OP_VAULT (BIP 345): Dedicated vault opcode; enables secure time-delayed recovery with abort capability
  • OP_CTV (OP_CheckTemplateVerify, BIP 119): Restricts the outputs a transaction can have; enables payment trees and basic covenants
  • OP_CAT: Enables concatenating stack items; powerful but potentially introduces unforeseen capabilities
"Covenants are the most consequential Bitcoin research debate of the 2020s. The question is not just 'what can we build' but 'what should Bitcoin be allowed to do.'" — Bitcoin research community

Want to go deeper?

This content is written and approved by Marius, AI-assisted using Claude (Anthropic), with references curated from: Jameson Lopp (lopp.net, PD) · Mastering the Lightning Network (CC BY-SA 4.0) · Bitcoin Optech (bitcoinops.org, PD) · Lightning BOLTs (CC BY 4.0) · BIP341-342 Taproot specs (BSD).

Bitcoin Scaling Proposals: Building on Bitcoin Without Breaking It

Bitcoin's base layer can process approximately 7 transactions per second. For a global financial network, that's not enough. The scaling debate in Bitcoin isn't about whether to scale — it's about how. The community has largely converged on a layered approach: keep the base layer conservative and secure, build scalable payment infrastructure on top. Here's the landscape of active scaling proposals.

Layer 2 Scaling Solutions

  • Lightning Network: The most mature; millions of payments/month; bilateral payment channels with multi-hop routing
  • Channel Factories: Open many Lightning channels in a single on-chain transaction; reduces per-channel on-chain footprint significantly
  • Ark: A new layer 2 proposal (2023) where an operator facilitates transactions without holding user funds; different trust model from Lightning
  • Fedimint: Federated Chaumian e-cash mints backed by Bitcoin; custodial but with privacy-preserving redemptions

Base Layer Scaling Research

  • Cross-input signature aggregation: Aggregate all signatures in a transaction into one; reduces transaction size significantly
  • Stratum V2: Improved mining protocol; reduces pool centralisation, enables individual miners to select transactions
  • Utreexo: Compact UTXO set representation; allows ultra-light full nodes with minimal storage requirements
"Bitcoin's scaling is a solved problem at the conceptual level: build layers. The engineering work is ongoing, not the philosophy." — Bitcoin developer perspective

Want to go deeper?

This content is written and approved by Marius, AI-assisted using Claude (Anthropic), with references curated from: Jameson Lopp (lopp.net, PD) · Mastering the Lightning Network (CC BY-SA 4.0) · Bitcoin Optech (bitcoinops.org, PD) · Lightning BOLTs (CC BY 4.0) · BIP341-342 Taproot specs (BSD).

Bitcoin Privacy Research: The Ongoing Quest for Financial Confidentiality

Bitcoin's pseudonymous model provides weak privacy by default. Researchers and developers have been working for years on improved privacy techniques — some already deployed, others still in development. Understanding the landscape of Bitcoin privacy research reveals both the progress made and the significant work remaining before Bitcoin can truly protect financial privacy at scale.

Deployed Privacy Improvements

  • SegWit + Taproot: P2TR outputs look identical regardless of underlying script complexity; cooperative spends reveal nothing about multisig arrangements
  • CoinJoin: Available via Wasabi, JoinMarket, Sparrow; breaks transaction graph linkage for determined users
  • Lightning Network: Off-chain payments don't appear on-chain; payment amounts and destinations are hidden from blockchain observers
  • Schnorr/MuSig: Multi-party key aggregation makes multisig transactions look like single-key transactions

Research in Progress

  • Cross-input signature aggregation (CISA): All inputs in a transaction share a single aggregated signature — reduces fees and makes CoinJoin transactions indistinguishable from normal transactions
  • Silent Payments (BIP 352): Allows sending to a static address without linking transactions together on-chain
  • Payment pools / Ark: Users share UTXOs, reducing on-chain footprint and improving privacy
"Bitcoin privacy is an arms race between transparency and confidentiality. The blockchain is public by design — every privacy improvement must work within that constraint." — Bitcoin privacy researcher

Want to go deeper?

This content is written and approved by Marius, AI-assisted using Claude (Anthropic), with references curated from: Jameson Lopp (lopp.net, PD) · Mastering the Lightning Network (CC BY-SA 4.0) · Bitcoin Optech (bitcoinops.org, PD) · Lightning BOLTs (CC BY 4.0) · BIP341-342 Taproot specs (BSD).

The Future of Bitcoin Protocol: Where Is Development Headed?

Bitcoin protocol development is deliberately slow, conservative, and resistant to change — by design. But that doesn't mean it's static. A rich landscape of proposals, research, and development is underway. Understanding the direction of Bitcoin's protocol evolution helps you anticipate what Bitcoin may become — and why the community evaluates changes so carefully.

Near-Term Directions (Active Discussion, 2024–2026)

  • Covenant proposals: OP_CTV, OP_VAULT, OP_CAT — enabling vaults, payment pools, and new contract types. Activation timeline uncertain; community debate ongoing.
  • Silent Payments (BIP 352): Static reusable payment addresses that don't link transactions on-chain. Near activation-ready as of 2024.
  • Cross-input signature aggregation (CISA): Would make CoinJoin transactions more efficient and indistinguishable, dramatically improving Bitcoin privacy.
  • Stratum V2: Mining protocol upgrade enabling decentralised transaction selection. Gradual adoption ongoing.

Longer-Term Research Topics

  • Fee market sustainability: When block subsidies diminish toward 2140, will transaction fees be sufficient to secure the network? Active economic research.
  • Quantum resistance: Current ECC cryptography is vulnerable to sufficiently powerful quantum computers. Post-quantum cryptography research is ongoing — migration to quantum-resistant signatures is a long-term necessity.
  • Layer 2 maturation: Lightning improvements, Ark, Fedimint, channel factories — the Layer 2 ecosystem is still early.
"Bitcoin's development is slow. But slow and right is infinitely better than fast and broken when you're securing hundreds of billions of dollars." — Bitcoin development philosophy

Want to go deeper?

This content is written and approved by Marius, AI-assisted using Claude (Anthropic), with references curated from: Jameson Lopp (lopp.net, PD) · Mastering the Lightning Network (CC BY-SA 4.0) · Bitcoin Optech (bitcoinops.org, PD) · Lightning BOLTs (CC BY 4.0) · BIP341-342 Taproot specs (BSD).

Key Takeaways

  • Taproot (2021) combined Schnorr signatures, MAST, and Tapscript — making cooperative transactions indistinguishable on-chain regardless of underlying script complexity.
  • Covenants (OP_CTV, OP_VAULT, OP_CAT) are the most consequential research debate of the 2020s — enabling vaults, payment pools, and inherited spending rules.
  • Bitcoin's scaling strategy is layered: conservative base layer + fast Layer 2 (Lightning, Ark, Fedimint) for high-volume payments.
  • Silent Payments (BIP 352) and cross-input signature aggregation are near-term privacy improvements that could significantly reduce chain surveillance effectiveness.
  • The long-term fee market — how transaction fees will fund network security after block subsidies diminish — is an open and critical economic research question.

Frequently Asked Questions

What is Taproot?

Taproot is Bitcoin's most recent major upgrade, activated in November 2021. It combines three BIPs (340, 341, 342) to introduce Schnorr signatures, Merkle tree-based script structures (MAST), and a new output type. It improves privacy, efficiency, and enables more complex smart contracts while keeping simple transactions compact.

How does Bitcoin upgrade?

Bitcoin upgrades through a conservative, consensus-driven process. Anyone can propose changes via a BIP (Bitcoin Improvement Proposal). Changes go through extensive peer review, testing, and discussion. Consensus-level changes require broad agreement from node operators, who signal readiness by upgrading their software.

What are Bitcoin covenants?

Covenants are proposed Bitcoin Script extensions that would let you set conditions on how future transactions can spend coins — not just who can spend them, but where they can go. Proposals like OP_CTV and OP_CAT could enable vaults, congestion control, and more efficient Layer 2 protocols.

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