Ethereum L2 Drops Signatures to Fight Quantum Threat

BB84, an OP Stack rollup on Ethereum mainnet with chain ID 42069000, has removed conventional signatures and, since September 30, uses hash-chain accounts made by repeatedly hashing a secret with keccak-256; spending reveals the prior value for one-hash verification. Its founder, who posts as Hadamard, described the design in an October 24 Ethereum Research post and sought feedback. Ordinary Ethereum accounts use ECDSA signatures that a sufficiently large quantum computer running Shor’s algorithm could break, though no such machine exists today. The protocol defaults to 1,000 payments per chain, and Hadamard said a front-running flaw found while writing the post was fixed by an October 21 first-commit-wins rule.