Yoshimichi Tanizawa

High speed prototype quantum key distribution system and long term field trial

Securing information in communication networks is an important challenge in todays world. Quantum Key Distribution (QKD) can provide unique capabilities towards achieving this security, allowing intrusions to be detected and information leakage avoided. We report here a record high bit rate prototype QKD system providing a total of 878 Gbit of secure key data over a 34 day period corresponding to a sustained key rate of around 300 kbit/s. The system was deployed over a standard 45 km link of an installed metropolitan telecommunication fibre network in central Tokyo. The prototype QKD system is compact, robust and automatically stabilised, enabling key distribution during diverse weather conditions. The security analysis includes an efficient protocol, finite key size effects and decoy states, with a quantified key failure probability of ε = 10⁻¹⁰.

Quantum key distribution with hacking countermeasures and long term field trial

Quantum key distribution’s (QKD’s) central and unique claim is information theoretic security. However there is an increasing understanding that the security of a QKD system relies not only on theoretical security proofs, but also on how closely the physical system matches the theoretical models and prevents attacks due to discrepancies. These side channel or hacking attacks exploit physical devices which do not necessarily behave precisely as the theory expects. As such there is a need for QKD systems to be demonstrated to provide security both in the theoretical and physical implementation. We report here a QKD system designed with this goal in mind, providing a more resilient target against possible hacking attacks including Trojan horse, detector blinding, phase randomisation and photon number splitting attacks. The QKD system was installed into a 45 km link of a metropolitan telecom network for a 2.5 month period, during which time the system operated continuously and distributed 1.33 Tbits of secure key data with a stable secure key rate over 200 kbit/s. In addition security is demonstrated against coherent attacks that are more general than the collective class of attacks usually considered.

Zero-Watt Networked Standby: Development and Evaluation of a Home A/V Network System

Energy conservation is an important global issue. Home is the third largest energy consumer, and 10% of the home energy is standby power of home appliances. The proliferation of home networks increases the standby power. The conventional technologies for low networked standby power such as WoL require continuous AC power, as much as 0.5 watts, to monitor wake-up signals. The large portion of the consumed power is due to the power loss in an AC-DC converter. Moreover, the technologies are applicable only to the specific network types such as Ethernet and IEEE802.11. We propose a solution to reduce the networked standby power down to zero virtually, regardless of the network type. For monitoring wake-up signals, the solution utilizes the precharged power in an ultra capacitor without using AC power supply almost all the time. In order to realize this idea, the solution also utilizes unique and simple protocol dedicated only to the networked standby /wake-up functionality. This protocolenables the monitoring circuit to consume very small power enough for the capacitor to supply. The networked standby/wake-up functionality is easily combined with any conventional network application protocol by protocol address mapping. As one realization example of our solution, we implemented an experimental system which is integrated with an ultra low power wireless signal receiver and extended UPnP protocol. The system evaluation showed that our solution achieves the zero-watt networked standby while keeping network functionalities. Moreover, the analysis of the results shows that the practical networked standby power is one seventeenth of the conventional technologies in usual usage. This corresponds to 1.11 kg-CO2 emission reduction per year per product.

An approach to integrate quantum key distribution technology into standard secure communication applications

Quantum Key Distribution (QKD) technology provides unconditional secure cryptography key sharing between two separate sites based on the laws of physics. With the shared keys, applications are able to communicate with each other in an information theoretically secure manner. We propose a method for providing secure communication that selects between QKD-based security and standard cryptography-based security automatically according to the current amount of QKD keys stored by QKD. The proposed method provides a QKD-based secure communication function. However, in the case of a shortage of QKD keys stored, the method alternatively provides a standard cryptography-based secure communication function to avoid a communication delay. Since the method has an OpenSSL-compatible interface, that is, a de facto standard cryptography library for secure communication, it makes it easy to port existing secure communication applications developed with the OpenSSL library to QKD-ready applications. It could also make it possible to phase QKD technology into existing secure communication applications. The quantitative performance evaluation showed the secure session establishment delay. Although the result reveals that the proposed method increases the session establishment delay, the delay overhead of the proposed cryptography method selection is 7 msec., which is acceptable for some practical applications. In addition, the result also shows that the delay difference from the standard cryptography can be reduced when the standard cryptography uses a larger key.

Zero-watt Networked Standby: Reducing Power Consumption of Home A/V Network Systems

Energy conservation is an important global issue. The home is the third largest energy consumer, and 10% of the home energy use is standby power of home appliances. The proliferation of home networks increases the standby power. The conventional technologies for low networked standby power such as WoL require continuous AC power, as much as 0.5 watts, to monitor wake-up signals. A large portion of the consumed power is due to the power loss in the AC-DC converter. Moreover, the technologies are applicable only to the specific network types such as Ethernet and IEEE802.11. We propose a solution to reduce the networked standby power down to zero virtually, regardless of the network type. For monitoring wake-up signals, the solution utilizes the pre-charged power in an ultra capacitor without using the AC power supply for almost all the time. In order to realize this idea, the solution also utilizes a unique and simple protocol dedicated only to the networked standby/wake-up functionality. This protocol enables the monitoring circuit to consume a very small amount of power, small enough for the capacitor to supply. The networked standby/wake-up functionality is easily combined with any conventional network application protocol by protocol address mapping. As one realization example of our solution, we implemented an experimental home A/V system which is integrated with an ultra low power wireless signal receiver and extended UPnP protocol. The system evaluation showed that our solution achieves the zero-watt networked standby while keeping network functionalities. Moreover, the analysis of the results based on a statistical survey shows that the practical networked standby power is 30 mW when our solution is applied to a TV system, which corresponds to one seventeenth of a conventional technology, WoL. It means that our solution improves power consumption by 22% which corresponds to 1.11 kg-CO2 emission reduction per year per product.