Plug and play encryption

Abstract

We present a novel protocol for secret key exchange that is provably secure against attacks by an adversary that is free to attack zero, one, or both parties in an adaptive fashion, at any time. This high degree of robustness enables larger, multiparty interactions (including multiparty secure computations) to substitute our protocol for secure private channels in a simple, plug-and-play fashion, without simultaneously limiting security analysis to attacks by static adversaries, i.e. adversaries whose corruption choices are fixed in advance. No reliance on the assistance of third parties or on erasing partial computations is required. In addition to providing order-of-magnitude speedups over alternative approaches, the simplicity of our protocols lends itself to simple demonstrations of security. We present constructions that are based on a novel and counterintuitive use of the Diffie-Hellman key exchange protocol; our methods extend to other standard cryptographic assumptions as well.