Someone built an Ethereum L2 with no signatures at all. Your account is a chain of hashes, and every payment tears one off.
BB84, an OP Stack rollup live on mainnet since Sept. 30, swaps ECDSA for keccak-256 hash chains. To pay, you commit, then reveal the next preimage. The bet is that a quantum computer can break a signature but not a hash. Bridged USDC and EURC only, gas-free.
The founder's Ethereum Research post is unusually honest. They found a commit-hijacking bug while writing it and patched it Oct. 21. The sequencer is theirs, there are no fault proofs, and by their own count it wouldn't even rate Stage 0 on L2BEAT. Miss the renewal step on your last hash and the address is dead.
Safe from the computers of 2040. Still trusting one operator in 2026.