Reply to: “Comment on: ‘How much security does Y-00 protocol provide us?’ ” [Phys. Lett. A 346 (2005) 1]

• Published in: Physics letters. A Vol. 346; no. 1; pp. 7 - 16
• Main Authors: Nishioka, Tsuyoshi, Hasegawa, Toshio, Ishizuka, Hirokazu, Imafuku, Kentaro, Imai, Hideki
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2005
• Subjects: Classical stream cipher; Quantum cryptography; Y-00 protocol; Y-00 protocol; Classical stream cipher; 03.67.Dd; Quantum cryptography
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/j.physleta.2005.08.023

In a recent paper titled “Comment on: ‘How much security does the Y-00 protocol provide us?’ ” [H.P. Yuen, P. Kumar, E. Corndorf, Phys. Lett. A 346 (2005) 1–6], the authors critically examine our idea [T. Nishioka, T. Hasegawa, H. Ishizuka, K. Imafuku, H. Imai, Phys. Lett. A 327 (2004) 28–32] that the Y-00 protocol is essentially as secure as classical stream ciphers. We clarify our idea in more detail than our previous paper and show that the Y-00 protocol can be considered as a classical non-random stream cipher, as was claimed in [T. Nishioka, T. Hasegawa, H. Ishizuka, K. Imafuku, H. Imai, Phys. Lett. A 327 (2004) 28–32]. We also provide an analysis on key generation with the improved Y-00 protocol, which is implemented with weak coherent states.