Bitcoin Improvement Proposal 360 (BIP 360) has been merged into the official Bitcoin Improvement Proposals repository on GitHub, making the latest draft an official, numbered BIP that the ecosystem can reference and iterate on.
That “merged into the BIPs repo” milestone is not the same thing as a Bitcoin network upgrade going live. The BIPs repository is primarily a publication and archival venue, and publication does not imply consensus or imminent activation.
What BIP 360 Proposes
BIP 360, titled “Pay-to-Merkle-Root (P2MR),” proposes a new output type that is intended to preserve most of the practical benefits of Taproot script trees while removing Taproot’s quantum-vulnerable key-path spend.
In plain terms, Taproot today gives spenders two primary ways to spend:
- Key-path spend: spend with a signature against a public key committed in the output.
- Script-path spend: reveal the relevant script branch and a Merkle proof.
BIP 360’s core move is simple: keep the script-tree approach, but remove the key-path option entirely for this new output type. That means P2MR outputs commit only to the Merkle root of a script tree, rather than also committing to an internal key that could become a quantum target after being exposed.
The draft frames this as an “opt-in” hardening path against long-exposure quantum attacks, where an attacker has a long time window to target public keys exposed on-chain. The text also explicitly notes that this does not solve short-exposure attacks, such as a future quantum attacker targeting a public key visible in the mempool while a transaction is waiting to confirm.
Why This Gets Framed as “Quantum Resistance”
The headline risk being discussed is that a sufficiently capable quantum computer could use Shor’s algorithm to recover a private key from an exposed elliptic-curve public key. The BIP text argues that the earliest realistic risk window is “long exposure,” meaning keys that are visible on-chain for long periods, because an attacker would have far more time to run key recovery against historical data.
Taproot key-path spends are part of that narrative because Taproot outputs commit to a public key. Even if users spend quickly, the key material can become visible and persist in the blockchain record once spent, which is exactly the kind of long-lived target the draft is trying to minimize.
BIP 360’s positioning is, effectively: remove the key-path spend in a Taproot-like structure and make the default spend path be a script-path, which can be designed to reveal less quantum-vulnerable key material over time.
What Changes for Users and the Ecosystem
Nothing changes on the Bitcoin network just because BIP 360 is published. For anything like P2MR to be usable on mainnet, the proposal would need a separate implementation track, broad review, and an activation process consistent with consensus changes. BIP 360 is explicitly scoped as a soft fork proposal in the “Consensus (soft fork)” layer.
If the idea progresses, the practical implications would be felt mostly by wallet developers, hardware wallet vendors, exchanges, and libraries:
- Wallet support would need to add a new output type and address handling logic.
- Infrastructure would need to update parsing, signing flows (script-path-only for P2MR), and fee estimation assumptions for the larger witness data that comes with script-path spends.
- Exchanges and custodians would need operational comfort with a new, opt-in output class and any associated policy changes.
The draft also proposes that P2MR uses SegWit version 2 and indicates mainnet addresses starting with “bc1z” in its example format. That detail matters because it signals potential downstream work: bech32m tooling, address UX, and conservative rollout strategies similar to how Taproot adoption evolved over time.
What To Watch Next
For readers tracking whether this becomes more than an archival milestone, the next signals are procedural and technical, not price-driven:
- Ongoing technical discussion in developer venues, including review of tradeoffs like witness size, privacy characteristics, and interoperability with existing Taproot workflows.
- Any reference implementations or experimental branches that show how P2MR validation and policy could look in practice.
- Whether the conversation shifts from “remove key-path spends” to broader post-quantum signature discussions, which the BIP itself treats as a separate, future step.
In short, BIP 360’s addition to the official repository is a meaningful documentation milestone, and it clarifies a specific design direction: an opt-in, Taproot-like output that reduces long-exposure quantum risk by removing key-path spends. The market impact, if any, is likely downstream and gradual, because the real gating factor is adoption and activation, not the BIP number itself.
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