Very cool and simple. The notion of "time" may be a bit misleading but actually the client just requires to generate an unguessable rand, think at it like getti

Very cool and simple. The notion of "time" may be a bit misleading but actually the client just requires to generate an unguessable rand, think at it like getting a string from /dev/urandom, so actually time is completely not part of the protocol which is great (also avoiding to deal with client IDs can be nice in practice).