Masking messages in chaos

Abstract

Two identical non-linear systems exhibiting chaotic motion sometimes can be synchronized by allowing them to share one common variable. This suggests the possibility of embedding messages in the chaotic carrier signal produced by one of them, and retrieving the masked information using the other synchronized system. One major weakness of this idea is that, under appropriate conditions, the messages can be easily cracked using a suitable return map that requires no reconstruction of the full chaotic attractor. We show that this disadvantage can be dismissed if the synchronizing signal is sent regularly at a finite time interval instead of continuously.