4096-level intensity modulation signals for secure optical communication by Y-00 cipher protocol are experimentally measured by direct detection. It is shown intensity noise masks 80-signal levels disabling correct signal level discrimination by eavesdropper's direct detection measurement.
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.
In any communication system, all data including encrypted data by the mathematical cipher are transmitted under the strict rule of the interface frame. Attacker can easily acquire the whole data the same as the data of legitimate users including the address, routing information and so on from the transmission line by tapping.
This is very risky, especially for the secret sharing data center operations. So to hide the whole data in the transmission line is very attractive to ensure the high security level. This can be realized by Y-00 type random cipher that the ciphertext of simple mathematical cipher by PRNG is randomized by quantum noise and it gives a masking effect against the attacker's security analysis. This paper clarifies quantitative properties on the masking effect in the random cipher by Y-00 protocol, and shows the fact that a scheme by the intensity modulation may provide the greatest masking effect, even if the attacker employs the universal heterodyne receiver.
In any communication system, all data including encrypted data by the mathematical cipher are transmitted under the strict rule of the interface frame. Attacker can easily acquire the whole data the same as the data of legitimate users including the address, routing information and so on from the transmission line by tapping. This is very risky, especially for the secret sharing data center operations. So to hide the whole data in the transmission line is very attractive to ensure the high security level. This can be realized by Y-00 type random cipher that the ciphertext of simple mathematical cipher by PRNG is randomized by quantum noise and it gives a masking effect against the attacker's security analysis. This paper clarifies quantitative properties on the masking effect in the random cipher by Y-00 protocol, and shows the fact that a scheme by the intensity modulation may provide the greatest masking effect, even if the attacker employs the universal heterodyne receiver.