This paper presents the integrated circuit design methodology of ultrafast encryption and decryption circuits for optical processing and communication at 40 and 120 Gb/s. The simulation of optical encryption and decryption evolved by proposed design circuits of semiconductor optical amplifier (SOA)-Mach-Zehnder interferometer structure is developed from an SOA, attenuator, and erbium-doped fiber amplifiers combination at 40 and 120 Gb/s and further used for transmission.