Insider-proof encryption with applications for quantum key distribution

We introduce insider-proof private channels which are private channels that additionally allow for security even when the key is correlated with the message. This prevents an insider, who has access to secret keys and the capability of choosing messages to be sent on the channel, from signalling to someone who can read the ciphertexts. We give a construction for approximately insider-proof private channels using 2-universal hash functions. Quantum key distribution (QKD) offers the promise of information-theoretically secure communication, provided a number of assumptions are met. Ideally, the number of these assumptions required in a protocol should be reduced to a minimum. This is the motivation behind device independent QKD (DIQKD) protocols which use an adversarial model for the quantum devices. However, a previous report [3] pointed out that current protocols for DIQKD can leak key to an outside adversary when devices are used repeatedly. We show how to use the insider-proof private channel to allow DIQKD protocols to reuse devices any desired number of times without leaking information. © 2014 Springer International Publishing Switzerland