Chaotic Encryption Algorithm Against Chosen-Plaintext Attacks in Optical OFDM Transmission

We propose and demonstrate a physical-layer encryption algorithm against chosen-plaintext attacks (CPAs) in optical orthogonal frequency-division multiplexing (OOFDM) transmission, where the cyphertexts are dynamically generated for the first time by incorporating the random feature of the input data. The multiple-fold encryption algorithm consists of chaotic subcarrier allocation scrambling in time/frequency domains, chaotic phase rotation of subcarriers, as well as chaotic training sequence, which creates a total huge key space of 10194by using a 4-D hyperdigital chaos. The transmission of 8.9-Gb/s 16-QAM encrypted OOFDM data is demonstrated over 20-km standard single-mode fiber. The proposed encryption scheme provides excellent confidentiality of OOFDM transmission against the brute-force attacks and CPAs.