  A secure optical communication requires both high transmission efficiency and
high authentication performance, while existing cryptographic key distribution
protocols based on ghost imaging have many shortcomings. Here, based on
computational ghost imaging, we propose an interactive protocol that enables
multi-party cryptographic key distribution over a public network and
self-authentication by setting an intermediary that shares partial roles of the
server. This fragment-synthesis-based authentication method may facilitate the
remote distribution of cryptographic keys.
