Authors:
Ahmad Kamal
1
and
Keiichi Iwamura
2
Affiliations:
1
Department of Information and Computer Technology, Tokyo University of Science, Tokyo, Japan
;
2
Department of Electrical Engineering, Tokyo University of Science, Tokyo, Japan
Keyword(s):
Searchable Encryption, Threshold Secret Sharing, TTP-Aided, Secure Computation, Secure Storage, Clouds, Cloud Security, Information Security.
Abstract:
In recent years, the introduction of services such as storage-as-a-service has enabled users to outsource their data to cloud servers to mitigate the cost of physical storage infrastructure. Moreover, cloud storage allows users to access data anywhere. However, outsourcing sensitive data to cloud servers also introduces concerns regarding data leakage and privacy. Therefore, these data must be encrypted before storage. Searchable encryption (SE) is a method that allows data to be searched in its encrypted state. SE uses symmetric key encryption, public key encryption, or secret sharing. SE using symmetric and public key encryptions can be implemented using one cloud server. However, most SEs utilize the search index for efficiency, which incurs the additional cost of constantly updating the search index. SE using secret sharing is computationally light. Therefore, a direct search over ciphertext is possible without sacrificing the efficiency. However, it requires multiple, independen
tly managed cloud servers. In this study, by effectively using a trusted third party, we demonstrate that realizing an SE with a single cloud server is possible, even if secret sharing is used, thereby reducing the total running cost and communications required. Moreover, we demonstrate that the proposed method is secure against a semi-honest adversary.
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