Panoramic review of the Bitcoin protocol layer in 2025
Source: ChainFeeds Research
Bitcoin Optech'sAnnual summaryIt has historically been seen as a technical weather vane for the Bitcoin ecosystem. It doesn't pay attention to currency price fluctuations.Record only the most realistic pulse of the Bitcoin protocol and critical infrastructure。
The 2025 report revealed a clear trend:Bitcoin is undergoing a paradigm shift from “passive defense” to “active evolution.”
Over the past year, the community was no longer satisfied with fixing bugs, but began to systematically address survival-level threats (such as quantum computing) and aggressively explore the boundaries of scalability and programmability without sacrificing decentralization. This report is not only a memorandum from developers, but also a key index for understanding Bitcoin's asset attributes, cybersecurity, and governance logic in the next five to ten years.
Core findings
Throughout 2025, Bitcoin's technological evolution showed three core characteristics, which are the keys to understanding the following 10 major events:
Preemption of defense:The defense roadmap against quantum threats became clear and practical for the first time, and security thinking extended from the “now” to the “post-quantum era.”
Functional stratification:The high-intensity discussion of the soft fork proposal and the “hot plug” evolution of the Lightning Network showed that Bitcoin is achieving the architectural goals of “stable at the bottom and flexible at the top layer” through hierarchical protocols.
Decentralized infrastructure:From the mining protocol (Stratum v2) to node verification (uTreexo/SwiftSync), a large amount of engineering resources have been invested in lowering the threshold of participation and improving censorship resistance, with the aim of countering the centralized gravity of the physical world.
Bitcoin Optech's annual report covers hundreds or thousands of code submissions, mailgroup discussions, and BIP proposals over the past year. To extract the real signal from technical noise, I excluded updates limited to “partial optimization” and screened out the following 10 ecologicalStructural effectsevents.
1. Systematic defense and “hardening roadmap” against quantum threats
[Status: Research and long-term proposals]
2025 marks a qualitative shift in the Bitcoin community's attitude towards quantum computing threats, moving from theoretical discussions to engineering preparations. BIP360 received a number and changed its nameP2TSH (Pay to Tapscript Hash). This is seen both as an important stepping stone on the quantum hardening route, and more generally serves certain Taproot use cases (such as promise structures that don't require internal keys).
At the same time, the community discussed more specific quantum security signature verification solutions in depth.Including on the premise that corresponding scripting capabilities are introduced in the future (such as re-introducing OP_CAT or adding new signature verification operation codes), use OP_CAT to construct Winternitz signatures, discuss STARK authentication as a native scripting capability, and optimize hash signature schemes (such asSLH-DSA/SPHINCS+) on-chain costs.
The reason this topic is at the top is because it touches on the mathematical cornerstone of Bitcoin. If quantum computing actually weakens the elliptic curve discrete logarithm hypothesis in the future (thereby threatening the security of ECDSA/Schnorr signatures), it will triggerSystematic migration pressure and safe stratification of historical output. This forces Bitcoin to prepare an upgrade path ahead of time at the protocol and wallet layers. For long-term holders, choosing a hosting plan with an upgrade roadmap and security audit culture, and focusing on possible future migration windows will become compulsory courses in asset preservation.
2. A blowout of soft fork proposals: the cornerstone of building a “programmable treasury”
[Status: High Density Discussion/Draft Stage]
This year was a year of intense discussions on soft fork proposals, with a focus on how to unleash the expressive power of the script while maintaining minimalism. Contractual proposals such as CTV (BIP119) and CSFS (BIP348), as well as technologies such as LUNHANCE and OP_TEMPLATEHASH, are all trying to introduce more secure “restrictive clauses” for Bitcoin. In addition, OP_CHECKCONTRACTVERIFY (CCV) became BIP443, and various arithmetic operation code and script recovery proposals are waiting for consensus.
These seemingly obscure upgrades actually add new “laws of physics” to global value networks.They are expected to make the native “vaults (vaults)” structure simpler, more secure, and standardisable, and allow users to set up mechanisms such as delayed withdrawals and cancellation windows to achieve “programmable self-protection” at the level of protocol expressiveness.At the same time, these capabilities are expected to greatly reduce the interaction cost and complexity of second-layer protocols such as Lightning Network and DLC (discrete logarithmic contract).
3. “Censorship-resistant” restructuring of mining infrastructure
[Status: Experimental Implementation/Protocol Evolution]
The decentralization of the mining layer directly determines Bitcoin's censorship-resistant properties. In 2025, Bitcoin Core 30.0 introduced an experimental IPC interface.Greatly optimized the efficiency of interaction between the mining pool software/Stratum v2 service and Bitcoin Core's verification logic, reducing reliance on inefficient JSON-RPC, paving the way for Stratum v2 integration.
One of Stratum v2's key capabilities (when using mechanisms such as Job Negotiation) is to further decentralize transaction options from the mining pool to a more decentralized miner side, thereby improving censorship resistance.Meanwhile, the advent of MevPool attempted to passBlinded templates and market competitionTo solve the MEV problem: Ideally, multiple marketplaces should coexist to avoid a single point market becoming a new centralized hub. This is directly related to whether the transactions of ordinary users can still be fairly packaged in extreme environments.
4. Immune System Upgrades: Vulnerability Disclosure and Differential Fuzzy Testing
[Status: Ongoing engineering operations]
Bitcoin's security relies on self-inspection before a real attack. In 2025, Optech recorded a number of bug disclosures targeting Bitcoin Core and Lightning implementations (such as LDK/LND/eClair), covering everything from funds stuck to privacy de-anonymization, and even serious coin theft risks. This year, Bitcoinfuzz used “differential fuzzing (differential fuzzing)” technology to uncover more than 35 deep bugs by comparing the responses of different software to the same data.
This intense “stress test” is a sign of ecological maturity. It is like a vaccine. Although it exposes the lesion in the short term, it significantly enhances the system's immunity in the long run. It's also a wake-up call for users who rely on privacy tools or the Lightning Network: no software is perfect, and keeping key components updated is the simplest rule to keep deposits safe.
5. Lightning Network Splicing: A “Hot Update” for Channel Funding
[Status: Experimental support across implementations]
Lightning Network (Lightning Network) ushered in a major breakthrough in usability in 2025:Splicing (splicing/channel hot update). This technology allows users toDynamically adjust funds (deposit or withdraw) without closing the channelCurrently, it has experimental support in the three major implementations of LDK, Eclair, and Core Lightning. While the relevant BOLTs specifications are still being refined, compatibility testing across implementations has made significant progress.
Splicing is a key ability to “add or subtract money regardless of the channel.”It is expected to reduce payment failures and operating and maintenance frictions caused by inconvenient channel fund adjustments. In the future, wallets are expected to significantly reduce the cost of learning channel engineering, and allow more users to use LN as a payment layer close to a “balance account”This is the key puzzle for Bitcoin payments to large-scale daily use.
6. Verification cost revolution: let all nodes run on “civilian devices”
[Status: Prototype Implementation (SwiftSync)/Draft BIP (Utreexo)]
The moat of decentralization lies in the cost of verification. In 2025, two major technologies, SwiftSync and Utreexo, had a positive impact on the “full node threshold.”SwiftSync optimizes the UTXO set write path during IBD (initial block download): Only add chainstate when confirming that an output has not been spent at the end of IBD,Also, with a “least trust” hints file, the IBD process was accelerated by more than 5 times in the sample implementation, while opening up space for parallel verification.Utreexo (BIP181-183), on the other hand, uses the Merkle forest accumulator to allow nodes to verify transactions without storing the full UTXO set locally.
Advances in these two technologies mean it will become practical to run full nodes on resource-limited devices, increasing the number of independent validators in the network.
7. Cluster Mempool: Reshaping the underlying scheduling of the fee market
[Status: Close to release (Staging)]
Among the expected features of Bitcoin Core 31.0, the implementation of Cluster Mempool (cluster memory pool) is nearing completion.It introduces structures such as TxGraph to abstract complex transaction dependencies into “transaction cluster linearization/sequencing” problems that can be solved efficiently, making block template construction more systematic.
Although this is an upgrade to the underlying scheduling system, itIt is expected to improve the stability and predictability of rate estimates. By eliminating abnormal packaging sequences caused by algorithm limitations, the future Bitcoin network will perform more rationally and smoothly during congestion, and users' accelerated transaction requests (CPFP/RBF) can also take effect under a more certain logic.
8. Refined governance of the P2P transmission layer
[Status: Strategy Update/ Continuous Optimization]
The Bitcoin P2P network experienced a strategic inflection point in response to the surge in low-fee transactions that occurred in 2025. Bitcoin Core 29.1 lowered the default minimum relay rate to 0.1 SAT/vB.At the same time, the Erlay protocol continues to advance to reduce node bandwidth consumption; in addition, the community has put forward proposals such as “block template sharing” and continues to optimize compact block reconstruction strategies to cope with increasingly complex communication environments.
The viability of low-rate transactions to spread across the network when policies are more consistent and nodes default to lower thresholdsIt is expected to be improved。These directions are expected to reduce the hard bandwidth requirements of running nodesIt has further maintained the fairness of the network.
9. OP_RETURN and the blockchain space “commons tragedy” debate
[Status: Mempool Policy Change (Core 30.0)]
Core 30.0 relaxed OP_RETURN's strategic restrictions (allowing more output, removing part of the size limit), which sparked a heated philosophical debate about Bitcoin's use in 2025.Note that this is part of Bitcoin Core's Mempool Policy (default forwarding/standard policy), not a consensus rule; However, it will significantly affect whether transactions are easy to spread and be seen by miners, so it will actually affect the competitive landscape in the block space.
Proponents believe this will correct the incentive distortion, while opponents fear it will be seen as an endorsement of “on-chain data storage.” This debate reminds us that the rules for using blockchain space as a scarce resource (even if not at the level of consensus) are the result of a continuous game of interests between all parties.
10. Bitcoin Kernel: A “componentized” refactoring of the core code
[Status: Architecture Restructure/ API Release]
Bitcoin Core took a critical step in architectural decoupling in 2025: introducing the Bitcoin Kernel C API. This marks the separation of “consensus verification logic” from huge node programs into an independent, reusable standard component. Currently, this kernel can support external projects to reuse block verification and chain state logic.
“Encoreization” will bring structural security dividends to the ecosystem. It allows wallet backends, indexers, and analysis tools to directly call official verification logic, avoiding the risk of consensus differences caused by reinventing the wheel. This is like providing a standardized “original engine” for the Bitcoin ecosystem, and all kinds of applications built on this will be more robust.
Appendix: Mini-Glossary
To aid reading, here is a brief explanation of the key terms in the article:
UTXO (Unresolved Transaction Output):No transaction output is spent. The basic unit of Bitcoin ledger status records who owns how many coins.
IBD (Initial Block Download):Initial block download, the process of synchronizing historical data when a new node joins the network.
CPFP/RBF:Two transaction acceleration mechanisms. CPFP (parent compensation) relies on new transactions to drive old transactions; RBF (fee replacement) directly replaces low rate transactions with high-rate transactions.
Mempool (memory pool):Nodes are used to store buffers for “broadcasted but not yet packed into blocks” transactions.
BOLTS:A series of technical specifications for Lightning Networks (Basis of Lightning Technology).
MEV (Maximal Extractable Value):Maximum extractable value refers to the additional profit that miners can earn by reordering or reviewing transactions.
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