Changes to BIP-360 - Pay to Quantum Resistant Hash (P2QRH)

Protocol Design
, ,
5

Allow me to give some reasons of why I disagree here. Note that it’s just naming though, arguably not the most important part of a technical proposal..

  • The quantum threat might never materialize and a p2tr-like output type can still be useful without it. If this proposal is advertised as a solution for the quantum threat, it might not get any attention until that threat exists, which might be never.
  • The name “pay-to-quantum-resistant-hash” is confusing as it breaks with the convention of output types, that describe what you’re paying into. “pubkey-hash” being the hash of a pubkey, that can sign to spend, “script-hash” being the hash of a script, that should be fulfilled to spend. No “quantum resistant [thing]” is hashed here, so it sounds like you’re just paying to a hash, as if spending would be done by simply providing the preimage.
  • “quantum resistant hash” also sounds like you’re using some better more quantum-resistant hash function, but from reading the BIP it seems like you’re proposing to re-use SHA256 which in my limited QC understanding is quantum-safe? Can be seen as misleading.
  • Addresses are to be read by the sender and the sender doesn’t really care if the receiver’s wallet is quantum-resistant. Using letters in the address to convey information also sets a bad UX precedent as they’re not intended to be used that way.
  • In the scenario where a quantum threat is imminent or already passed and we are in a post-quantum world, I hope we don’t need address letters or output naming for developers to know what outputs they should be using.
  • Also, in such a world, any additional new feature we add to bitcoin will hopefully also be quantum resistant and I hope we won’t be naming every new output type as “pay to quantum resistant something”. Even other new features might be added before. Will we add OP_QUANTUMRESISTANTTXHASH, OP_CHECKQUANTUMRESISTANTCONTRACTVERIFY, etc?

TL;DR: I think pay-to-tapscript is useful outside of the QC context and association with it might delay interest until QC seems more relevant.

4 Likes