BIP-361 is a draft Bitcoin Improvement Proposal that would retire Bitcoin’s quantum-vulnerable signatures in two stages. First it would block new sends to vulnerable address types about three years after activation. Then, about five years after activation, a flag day would sunset legacy signatures. It is not active and has no activation date. It would only affect your coins if the Bitcoin network adopted it through a consensus change.<\/p>\n
This guide covers what the draft says, how it relates to BIP-360 (P2MR), why coins in early P2PK outputs, Satoshi’s included, are a special case, and what holders can sensibly do today. One caveat first: the draft is still being revised, so details may differ from the version you read.<\/p>\n
BIP-361 is titled “Post Quantum Migration and Legacy Signature Sunset.” Jameson Lopp and five co-authors wrote it, and it was submitted to the bitcoin\/bips repository as pull request #1895, merged on April 14, 2026<\/a>. Merging into the BIPs repository gives a proposal a number and a public home. It is not an endorsement, and it does not activate anything.<\/p>\n The BIP header<\/a> lists it as Status: Draft and Type: Informational, with “Requires: TBD Post Quantum Signature BIP.” That last line matters. The plan depends on a post-quantum signature standard that has not been written yet, so it cannot be deployed as it stands.<\/p>\n The timing follows a sharp drop in public estimates of what a quantum attack on Bitcoin would cost. In late March 2026, Google Quantum AI published “Safeguarding cryptocurrency by disclosing quantum vulnerabilities responsibly”<\/a> alongside a paper co-authored with the Ethereum Foundation and Stanford, “Securing Elliptic Curve Cryptocurrencies against Quantum Vulnerabilities.” It estimates that breaking secp256k1, the curve behind Bitcoin’s signatures, would take fewer than 500,000 physical qubits and run for minutes. SecurityWeek reports<\/a> that this is about ten times lower than earlier estimates.<\/p>\n The paper describes two circuit variants:<\/p>\n Google did not publish the circuits. It released a zero-knowledge proof instead, built with the SP1 zkVM and Groth16, so others can check the claim without being handed an attack blueprint. The paper does not claim that any existing machine can break Bitcoin. What it does is shorten the time the ecosystem can assume it has. For the same question on another chain, see our analysis of whether quantum computers can break Ethereum<\/a>.<\/p>\n A sunset only makes sense if there is somewhere safer to move coins. BIP-360 is the proposal most often discussed as that destination. According to Bitcoin Magazine<\/a>, it was merged into the BIPs repository on February 11, 2026. As with BIP-361, merging is not endorsement or activation, and no soft-fork signaling for it exists.<\/p>\n BIP-360 was first called P2QRH and was later renamed Pay-to-Merkle-Root (P2MR). Its authors are Hunter Beast, Ethan Heilman and Isabel Foxen Duke. As LearnBitcoin’s BIP-360 entry<\/a> describes it, P2MR is a SegWit version 2 output type with addresses starting “bc1z.” It works like Taproot without the key-path spend.<\/p>\n Taproot outputs commit to a public key directly on-chain. Anyone with a large enough quantum computer could target that key at any time. P2MR drops the key path and commits only to a Merkle root of spending scripts. That protects against long-exposure attacks, where a public key sits visible on-chain for months or years.<\/p>\n P2MR does not protect against short-exposure attacks. In those, an attacker would derive a private key during the window between a transaction being broadcast and being confirmed. Closing that gap needs post-quantum signatures, which is why BIP-361’s header still points to a signature BIP that is “TBD.”<\/p>\n The draft is built around activation-relative milestones, not calendar dates. No activation has been scheduled, so every date below is hypothetical. The sequence, as summarized on bips.dev<\/a> and in Decrypt’s coverage<\/a>, is:<\/p>\n\n
What is BIP-360 (P2MR), and how does it relate to BIP-361?<\/h2>\n
When would BIP-361 take effect? Phase A and Phase B<\/h2>\n