Complexity of Network Design for Private Communication and the P-vs-NP Question

We investigate infeasibility issues arising along network design for information-theoretically secure cryptography. In particular, we consider the problem of communication in perfect privacy and formally relate it to graph augmentation problems and the P-vs-NP-question. Based on a game-theoretic privacy measure, we consider two optimization problems related to secure infrastructure design with constraints on computational efforts and limited budget to build a transmission network. It turns out that information-theoretic security, although not drawing its strength from computational infeasibility, still can run into complexity-theoretic difficulties at the stage of physical network design. Even worse, if we measure (quantify) secrecy by the probability of information-leakage, we can prove that approximations of a network design towards maximal security are computationally equivalent to the exact solutions to the same problem, both of which are again equivalent to asserting that P = NP. In other words, the death of public-key cryptosystems upon P = NP may become the birth of feasible network design algorithms towards information-theoretically confidential communication.