The need
Quantum Key Distribution (QKD) has emerged as a powerful solution for securing digital communications in the era of quantum computing. While the theoretical QKD protocol is provably secure, the overall security of a QKD system relies on the hardware correctly implementing the protocol. Any deviations from this, could compromise security, since the system parameters are no longer matched to the theoretical security proofs. To ensure reliability and, consequently, security, there is a need for a standardized methodology to evaluate QKD hardware. This evaluation should be carried out by an independent expert body, separate from the vendor.
Solution
Recognising the importance of independent security assessment in establishing trust in QKD hardware, Toshiba and NPL recently joined forces on this front. NPL developed a series of tests to evaluate crucial hardware parameters essential for QKD security, applying them to Toshiba's QKD Transmitter and Receiver modules. The data collected by NPL validated the technical specifications of Toshiba’s QKD hardware.
One key performance metric for comparing QKD hardware is the rate at which secure bits are generated. NPL measured the variation in the secure bit rate for the entire system as the link loss was adjusted across a range of accurately calibrated values. NPL confirmed that the reported secure bit rates over NPL-calibrated attenuation links either matched or surpassed the rates specified in Toshiba’s product documentation.
NPL and Toshiba have published a White Paper describing this work, which can be downloaded here.
Impact
The independent evaluation of Toshiba QKD technology by NPL confirmed that all measured optical quantities were as specified, and thus, compatible with the requirements of the provably secure underlying theory.
The work also identified new approaches for evaluating QKD hardware and paves the way for further activities to fully validate the security of a QKD system, including the drafting by standards developing organisations of procedures for measuring security-critical parameters of QKD systems. This is an important step towards complete QKD product security assurance by independent verification to bolster trust in this emerging critical technology.
Quantum technologies
About Toshiba
Toshiba Corporation leads a global group of companies that combines knowledge and capabilities from over 145 years of experience in a wide range of businesses – from energy and social infrastructure to electronic devices – with world-class capabilities in information processing, digital and AI technologies. These distinctive strengths support Toshiba’s continued evolution toward becoming an Infrastructure Services Company that promotes data utilization and digitization, and one of the world’s leading cyber-physical-systems technology companies. Guided by the Basic Commitment of the Toshiba Group, “Committed to People, Committed to the Future,” Toshiba contributes to society’s positive development with services and solutions that lead to a better world. The Group and its 120,000 employees worldwide secured annual sales of 3.3 trillion yen (US$27.4 billion) in fiscal year 2021.