Cryptographic key exchange based on locationing information

This paper addresses the cryptographic key exchange problem in a wireless network. An infrastructure-based wireless network such as a Wireless LAN is considered. An indoor wireless locationing system, based on a collection of beacon nodes, is assumed to be present. The proposed technique makes use of ranging information between nodes to establish a shared secret key between security principals. The key exchange technique is based on the notion of symmetric ranging combined with Merkle’s puzzles. This technique is independent of any underlying encryption algorithm. The system’s security properties, in terms of the time to obtain the secret key and the time for an adversary to break the key, are analyzed using empirical implementations. The results show that the secret key can be established in five seconds between the principals, while it requires the adversary two orders of magnitude more time in some cases to substantially more than an hour (when the implementation times out) in most cases.