Information theoretic reductions among disclosure problems

Alice disposes of some number of secrets. She is willing to disclose one of them to Bob. Although she agrees to let him choose which secret he wants, she is not willing to allow him to gain any information on more than one secret. On the other hand, Bob does not want Alice to know which secret he wishes. An all-or-nothing disclosure is one by which, as soon as Bob has gained any information whatsoever on one of Alice´s secrets, he has wasted his chances to learn anything about the other secrets. We assume that Alice is honest when she claims to be willing to disclose one secret to Bob (i.e. she is not about to send junk). The only cheating Alice is susceptible of trying is to figure out which secret is of interest to Bob. We address the following question from an information theoretic point of view: what is the most elementary disclosure problem? The main result is that the general all-or-nothing disclosure of secrets is equivalent to a much simpler problem, which we call the two-bit problem.