Unbreakable distributed storage with quantum key distribution network and password-authenticated secret sharing
This work addresses the challenge of achieving unbreakable security for data storage in networks, which is critical for applications requiring long-term robustness, though it appears incremental as it builds on existing secret sharing and quantum key distribution methods.
The authors tackled the problem of ensuring perfect information-theoretic security in distributed storage systems by proposing a system that combines a user-friendly single-password-authenticated secret sharing scheme with secure transmission via quantum key distribution, and they demonstrated it in the Tokyo metropolitan area.
Distributed storage plays an essential role in realizing robust and secure data storage in a network over long periods of time. A distributed storage system consists of a data owner machine, multiple storage servers and channels to link them. In such a system, secret sharing scheme is widely adopted, in which secret data are split into multiple pieces and stored in each server. To reconstruct them, the data owner should gather plural pieces. Shamir's (k, n)-threshold scheme, in which the data are split into n pieces (shares) for storage and at least k pieces of them must be gathered for reconstruction, furnishes information theoretic security, that is, even if attackers could collect shares of less than the threshold k, they cannot get any information about the data, even with unlimited computing power. Behind this scenario, however, assumed is that data transmission and authentication must be perfectly secure, which is not trivial in practice. Here we propose a totally information theoretically secure distributed storage system based on a user-friendly single-password-authenticated secret sharing scheme and secure transmission using quantum key distribution, and demonstrate it in the Tokyo metropolitan area.