Y-00 Quantum-Noise Randomized Stream Cipher Using Intensity Modulation Signals for Physical Layer Security of Optical Communications

• Published in: Journal of lightwave technology Vol. 38; no. 10; pp. 2773 - 2780
• Main Authors: Futami, Fumio, Tanizawa, Ken, Kato, Kentaro
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.05.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Ciphers; Communication system security; Data encryption; Encryption; Exact solutions; Interception; Masking; Modulation; Noise; Noise intensity; Optical communication; Optical fiber communication; Optical fibers; Randomization; Security; Shot noise; Spontaneous emission
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2020.2985709

The Internet plays an essential role in modern societies and in the amount of sensitive data transported over the optical networks that shows its' importance has increased drastically. Therefore, it is critical to develop data protection schemes for optical fiber communications to provide user security. The Y-00 quantum-noise randomized stream cipher that employs extremely high-order modulation and restricts an attacker's interception of ciphertext is a practical candidate for providing data protection. In this article, we introduce the operation principle of the Y-00 cipher with respect to data encryption and decryption. The Y-00 cipher combines the mathematical encryption of multi-level signaling and physical randomness, and provides a high level of security to the physical layer of optical communications and a high communication performance. We also present the noise masking phenomenon of the Y-00 cipher with intensity modulation (IM). This noise masking is generated by shot noise, i.e., quantum noise and additive noise such as amplified spontaneous emission noise. The noise masking phenomenon fails an attacker's interception of the ciphertext. The secrecy of the IM Y-00 cipher is also discussed, and an approximate analytical solution is introduced for evaluating the probability of the attackers accurately guessing the ciphertext. Finally, the secrecy of a 1,000-km transmission system is experimentally demonstrated with the Y-00 cipher transceiver at data rate of 1.5-Gb/s using the derived analytical solution to deduce the high secrecy of the entire transmission system.