Optical Analog Noise Encryption With Adaptive Recovery of Two-Dimensional Keys

An optical analog noise encryption system with adaptive recovery of two-dimensional keys is proposed and demonstrated using regular triangle (RT)adaptive algorithm in an optical self-interference cancellation system at the designated receiver. Analog noise encryption and data modulation are performed in a single dual-drive Mach-Zehnder modulator at the transmitter, while decryption is performed in an electro-absorption modulated laser based adaptive cancellation system at the receiver. The weight and delay of the analog noise form the two-dimensional orthogonal encryption keys. Two sets of fingerprints are securely pre-shared for only once between the transmitter and designated receiver and stored before real transmission to ensure that both sides are legitimate users and facilitate adaptive key recovery when using RT adaptive algorithm at the legitimate receiver for retrieving the orthogonal keys. Without receiving the keys from the transmitter, the legitimate receiver is able to adaptively find the two orthogonal keys even under dynamic key changing scenario. In the experiment, a 3.5 GHz wideband analog noise is used to encrypt a 10 Gbps 16 quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) signal at 1.75 GHz. By recovering the orthogonal keys using RT algorithm and the unique pre-shared fingerprints, the designated receiver has successfully decrypted the encrypted signal by removing the analog noise as wide as 3.5 GHz, 28 dB stronger than the sensitive signal, which is by far the best performance in an optical analog noise encryption system.