Secret-Key Generation in Many-to-One Networks: An Integrated Game-Theoretic and Information-Theoretic Approach

Abstract This paper considers secret-key generation between several agents and a base station that observe independent and identically distributed realizations of correlated random variables. Each agent wishes to generate the longest possible individual key with the base station by means of public communication. All keys must be jointly kept secret from all external entities. Also each agent has a level of security clearance; this setup requires that keys generated by agents at a given level must be be kept secret from the agents at a strictly superior level. In this many-to-one secret-key generation setting, it can be shown that agents with the same level of security clearance can take advantage of a collective protocol to increase the sum-rate of their generated keys. However, when each agent is only interested in maximizing its own secret-key rate, agents may be unwilling to participate in a collective protocol. Furthermore, when such a collective protocol is employed, how to fairly allocate individual key rates arises as a valid issue. This paper studies this tension between cooperation and self-interest with a gametheoretic treatment. The work establishes that, for each level of security clearance, cooperation is in the best interest of all individualistic agents and that there exists individual secret-key rate allocations that incentivize the agents to follow the protocol. Additionally, an explicit low-complexity coding scheme based on polar codes and hash functions that achieves such allocations is proposed.