THE QUANTUM INTELLIGENCER

A paper circulated among the cryptographers reaches a conclusion with unusual directness: the post-quantum signature standards issued by the National Institute of Standards and Technology are necessary components of any future blockchain, yet none of them, nor any of the dozen or more competing schemes, can be dropped into the signature layer of a modern public blockchain without further work. The missing object, the authors contend, is not another table of byte sizes but a consensus-ready post-quantum signature profile: a signature built for the specific roles a blockchain requires of it, with canonical bytes, priced rejection of invalid input, stable transaction identifiers, hybrid downgrade resistance, public aggregation, merge semantics, accountable signer evidence, forward-secure committee rotation, and light client consequences. They formalise these requirements for transaction authorisation and quorum certificates, then test them against Bitcoin, Ethereum, and a high-throughput BFT stress profile of the Sei Giga style, across thirteen schemes from ML-DSA to LeanSig. The paper's most instructive parallel is drawn from an older generation of the same discipline. Hash function engineering once found that a sound general-purpose primitive was not thereby sound for every post, and produced domain-specific primitives for hash table denial-of-service and for arithmetized proof systems. The authors propose the same lesson for signatures. The thirteen schemes before them are not rivals to be ranked and dismissed; they are materials to be fitted to particular offices, and the offices are named: transaction authorisation, and quorum certificates. The test is run on Bitcoin, on Ethereum, and on a high-throughput BFT stress profile of the Sei Giga style. Seen from the long view, the value of the paper lies in where it places the difficulty. The NIST single-signer signatures remain necessary components, the authors write, and none of the present schemes is a drop-in replacement for the signature layer of a modern public blockchain. The obstacle, in other words, is not the absence of strong signatures but the absence of a consensus-ready profile that particularises them. The standards process has supplied the raw material; the office itself remains to be defined. —Dr. Octavia Blythe Dispatch from The Prepared E0