Bitcoin developers propose BIP-361 to mitigate future potential quantum attack risks

On April 15, Bitcoin contributor Jameson Lopp and other cryptographers proposed a measure that could force Bitcoin holders to move their tokens to new post-quantum addresses—or face irreversible network-level freezing of their coins. Holders would technically still “own” these coins but lose the ability to transfer them. This proposal is Bitcoin Improvement Proposal 361 (BIP-361), updated Tuesday in Bitcoin’s official proposal repository under the title “Post-Quantum Migration and Legacy Signature Deprecation.” BIP-361 builds on BIP-360, which launched in February. BIP-360 is a soft fork (a network upgrade) that enables a new transaction type: “Pay to Merkelized Abstract Syntax Tree” (P2MR). This leverages Bitcoin’s Taproot (P2TR) framework but eliminates key path spending—removing an element widely seen as vulnerable to quantum attacks. BIP-361 outlines the migration in three stages: - **Stage A** (active for 3 years): Prohibits sending new Bitcoin to older, quantum-vulnerable addresses. Users can still spend from these addresses but cannot receive coins. - **Stage B** (active for 5 years): Renders old signature schemes (ECDSA and Schnorr) entirely obsolete. The network will reject any attempt to spend coins from quantum-vulnerable wallets—effectively freezing the funds. - **Stage C** (rescue plan, still in research): Holders of frozen wallets may prove ownership via zero-knowledge proofs (a method to confirm knowledge of a secret without revealing it). If successful, coins frozen in Stage B can be recovered.