Open AccessDigital coherent PSK Y-00 quantum stream cipher with 217 randomized phase levels
Author(s) -
Ken Tanizawa,
Fumio Futami
Publication year - 2019
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.001071
Subject(s) - cipher , computer science , stream cipher , optics , phase shift keying , quantum noise , electronic engineering , physics , encryption , bit error rate , algorithm , cryptography , quantum , engineering , computer network , decoding methods , quantum mechanics
We report a 10-Gbaud fiber-optic cipher transmission system by using a phase-shift keying (PSK) Y-00 quantum stream cipher. The PSK Y-00 cipher is a symmetric-key direct data encryption technique based on extremely high-order random phase modulation using a pre-shared short key. Neighboring signal phases following encryption are masked by quantum (shot) noise, which provides security based on shot noise's inherent effects. To implement such a system, we utilize coarse-to-fine phase modulation with two cascaded phase modulators and digital decryption incorporated into digital signal processing (DSP) for intra-dyne coherent detection. We demonstrate 10-Gbaud PSK Y-00 cipher transmission over a 400-km standard single-mode fiber (SSMF). The coarse-to-fine phase modulation achieves 2 17 phase levels for signal masking by shot noise. The DSP with decryption realizes detection of the cipher without penalties. Masking 167 signal phase levels by shot noise is achieved at a bit-error ratio defined by a hard-decision forward-error correction threshold (3.8 × 10 -3 ) in the transmissions over the 400-km SSMF.