I've suggested this on the ACME list, actually; allowing people to put their ACME account public keys in DNS, rather than the random-per-transaction challenge s

I've suggested this on the ACME list, actually; allowing people to put their ACME account public keys in DNS, rather than the random-per-transaction challenge specified right now, which is quasi-unusable. The problem, apparently, is that CA forum rules require that a random challenge be used. Of course this doesn't make much sense in the context of ACME, where you have a private key identifying the user account. But this obstructs the specification of a deterministic challenge for DNS, alas.