How to hard-fork to save most users’ funds in a quantum emergency

The author argues that Ethereum is already well-positioned for a recovery hard fork in a quantum emergency, in which few users would lose funds. Under the proposed structure, the chain would revert blocks after the first block where large-scale theft is clearly underway, and traditional EOA-based transactions would be disabled. Users would then prove knowledge of a private preimage, using one of k approved hash functions, that maps to their address with a STARK proof, and their account code would switch to new validation code. Because STARKs are large, the proofs could be batched, with a STARK-of-STARKs keeping each user's preimage private from the aggregator.