As far as I understand, OTP usually works on a superficial layer by having two parties both know of a key and then authenticate each other by sharing a hash of the key and some sort of counter (e.g. currentTime mod someNumber) with each other. In theory, this means both parties can verify each other, as both have the capabilty to generate a OTP and both have the the capability to verify the integrity OTP given to them.
I'm looking for an OTP scheme between two parties where both parties can verify the validity of an OTP, but only one party can generate it. To my understanding, this would not work with the logic described above. Does such a protocol already exist? If not, is such a system even mathematically realizable?
Best,
Nicolas (using my brother's account for the extra reputation since I can't post with my fresh account :) )