The present invention relates generally to an integrated optics encryption device. The preferred embodiment of the invention is an integrated optics encryption device comprising a coherent light source connected to a multi-functional integrated optics chip (MIOC). The MIOC comprises two divergent paths with mirrored ends. The MIOC also has an encrypted message output. One path is connected to a message signal input that can alter the refractive index of the path. The other path is connected to a key signal input that can alter the refractive index of the other path.