Six contributors from the Bitcoin (BTC) quantum security space, including Casa co-founder Jameson Lopp, have published BIP-361. The proposal seeks to sunset legacy ECDSA/Schnorr signatures. The draft proposal, titled “Post Quantum Migration and Legacy Signature Sunset,” lays out a three-phase timeline that “turns quantum security into a private incentive. ” What is BIP-361, and What Does it Seek To Do? BIP-361 builds on BIP-360, which introduced a quantum-resistant output type called Pay-to-Merkle-Root (P2MR)