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.