A HASH-ONLY ROLLUP

Summary from the TLDR Crypto newsletter

The founder of bb84 payments has deployed an OP Stack L2 on Ethereum mainnet (chain ID 42069000, live since 2026-09-30) where L2 transactions carry no ECDSA signatures, replacing them with Lamport-style keccak-256 hash chains in which spending a transaction reveals the next preimage rather than a cryptographic signature. Each account derives from a secret seed generating a default 1,000-step hash chain, tracked by a NullifierTree predeploy, with two new EIP-2718 transaction types handling commit (0x7C) and reveal (0x7F) steps, and a "first commit wins" rule activated on October 21 to blunt front-running. The chain targets ~2^128 quantum work factor inside the L2 against Grover's algorithm, but ECDSA remains at the L1 boundary, fault proofs are absent, the sequencer is centralized, and stateful wallets mean losing chain position can lock users out.