The quantum key distribution (QKD) network with Vernam's one-time pad encryption and secret sharing are powerful security tools to realize an information theoretically secure (ITS) distributed storage system. In the work of Fujiwaraet al., a single-password-authenticated secret sharing (SPSS) scheme based on the QKD network and Shamirs secret sharing was experimentally demonstrated; it confirmed ITS data transmission, storage, authentication, and integrity. To achieve data integrity, an ITS message authentication code (MAC) tag is employed, and a data owner of the secret sharing performs both the MAC tag generation and verification. However, for a scenario in which the data owner and end users are different entities, the above approach may not work, since the data owner can cheat the end users. In this article, we resolve this problem by proposing an ITS integrity protection scheme employing a third-party verification with time-stamp. The ITS integrity protection is realized by two steps: integrity check by the data owner at data reconstruction and data integrity certification by the data owner, the end user, and the third-party verifier using a MAC based on universal2hash function and random number provided from the QKD network. In addition to introducing the third-party verifier, we institute “a trusted calculator,” which computes shares of the data and MAC tags and sends MAC tags to the third-party verifier. The random number used in calculation is stored in the trusted calculator. We implement this scheme on the SPSS system installed in the Tokyo QKD Network.
The quantum key distribution (QKD) network with Vernam's one-time pad encryption and secret sharing are powerful security tools to realize an information theoretically secure (ITS) distributed storage system. In the work of Fujiwaraet al., a single-password-authenticated secret sharing (SPSS) scheme based on the QKD network and Shamirs secret sharing was experimentally demonstrated; it confirmed ITS data transmission, storage, authentication, and integrity. To achieve data integrity, an ITS message authentication code (MAC) tag is employed, and a data owner of the secret sharing performs both the MAC tag generation and verification. However, for a scenario in which the data owner and end users are different entities, the above approach may not work, since the data owner can cheat the end users. In this article, we resolve this problem by proposing an ITS integrity protection scheme employing a third-party verification with time-stamp. The ITS integrity protection is realized by two steps: integrity check by the data owner at data reconstruction and data integrity certification by the data owner, the end user, and the third-party verifier using a MAC based on universal2hash function and random number provided from the QKD network. In addition to introducing the third-party verifier, we institute “a trusted calculator,” which computes shares of the data and MAC tags and sends MAC tags to the third-party verifier. The random number used in calculation is stored in the trusted calculator. We implement this scheme on the SPSS system installed in the Tokyo QKD Network.
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 (≤90 km).
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.
The amount of digital data that requires long-term protection of integrity, authenticity, and confidentiality grows rapidly. Examples include electronic health records, genome data, and tax data. In this paper we present the secure storage system LINCOS, which provides protection of integrity, authenticity, and confidentiality in the long-term, i.e., for an indefinite time period. It is the first such system. It uses the long-term integrity scheme COPRIS, which is also presented here and is the first such scheme that does not leak any information about the protected data. COPRIS uses information-theoretic hiding commitments for confidentiality-preserving integrity and authenticity protection. LINCOS uses proactive secret sharing for confidential storage of secret data. We also present implementations of COPRIS and LINCOS. A special feature of our LINCOS implementation is the use of quantum key distribution and one-time pad encryption for information-theoretic private channels within the proactive secret sharing protocol. The technological platform for this is the Tokyo QKD Network, which is one of worlds most advanced networks of its kind. Our experimental evaluation establishes the feasibility of LINCOS and shows that in view of the expected progress in quantum communication technology, LINCOS is a promising solution for protecting very sensitive data in the cloud.
Abstract Supercomputers, quantum computers, other computers, and algorithmic advancements that can break cryptographic systems currently in use are becoming a reality. For information that requires long-term confidentiality (e.g. national security, military security, genomic data etc.), the threat of eavesdropping must be seriously considered. The leakage of such information would not only cause temporary confusion but would also have serious repercussions for future generations. Part of such important data are already being exchanged over the Internet using cryptography that is not resistant to quantum computers. Considering the possibility of harvest attacks on information that must be kept secret for centuries, developing a technology that can immediately eliminate the risk of eavesdropping in principle is desirable. In response to these demands, we previously developed an information-theoretically secure method for data transmission, storage, recovery, and authentication with a single password using a quantum key distribution network called a quantum secure cloud. We now apply this technology to develop an information-theoretically secure long-distance data-relay function and succeed in developing a distributed data-relay simulator that is compatible with current quantum key distribution networks. The throughput of this protocol is more than 10 Mbps for 10 MB data, so it can be applied to practical use.
With the increasing prominence of data security in cloud storage, we propose a practical and robust cloud storage scheme, which uses quantum random numbers as encryption keys, disperses the keys using Shamir’s secret sharing scheme, applies erasure coding to the ciphertext, and securely transmits the data through quantum key distribution protected networks to the distributed clouds. This system offers several key advantages, including quantum-level security, fault tolerance, and storage space saving. To validate its feasibility, we conduct comprehensive experimental tests covering essential functionalities such as encryption/decryption, key preservation, and data storage. By successfully demonstrating the effectiveness of our proposal, we aim to accelerate the application of quantum technology in cloud storage.
The security of quantum cryptography relies on the foundations of quantum mechanics, in contrast to traditional public key cryptography which relies on the computational difficulty of certain mathematical functions, and cannot provide any indication of eavesdropping or guarantee of key security. The proposal present in this work develops a quantum key distribution model to safeguard security in large networks, in the directions of classical cryptography and quantum cryptography. Two three-party Quantum key distribution are used in this model, one with implicit user authentication and the other with explicit mutual authentication, are proposed to demonstrate the merits of the new combination. The performance of Quantum Key Distribution (QKD) systems have notably progressed since the early experimental demonstrations. The current evolutions in QKD research indicate that the pace of this progression is very likely to be maintained, if not increased, in the future years. In parallel to these improvements of QKD techniques, commercial products are also being developed, making QKD deployment a feasible alternative for securing real data networks. Deployment of a real QKD network is however far from being straightforward. It requires development of a network architecture connecting multiple users that may possibly be very far away from each other. Considering the fact that the existing QKD links are only point-to-point, and intrinsically limited in distance, deployment of a practical QKD network structure is a nontrivial problem. The proposed work describes the proposed architecture for a QKD network specify the requirements relevant to the network design, protocols, and services. The objective of this specification is to define the major components and their main features The proposal provides security against such attacks as man-in-the-middle, eavesdropping and replay. It also improves the efficiency of the quantum key distribution which contains the fewest number of communication rounds among existing Quantum key distributions. In this model two parties can share and use a long-term secret (repeatedly). To prove the security of the proposed schemes, this proposed model provides a primitive called the Unbiased-Chosen Basis (UCB) assumption with the quantum key in angular positions.