A secure searchable encryption scheme for cloud using hash-based indexing (Q2119405)

This paper proposes a novel data encryption scheme with keyword-based search capabilities by employing a hash-based index structure. It employs the ElGamal additive homomorphic encryption based on elliptic curves to implement a top-\(k\) query algorithm using the secure addition of the term frequency and inverse document frequency (TF-IDF). This scheme can be used in cloud storage scenarios since, in comparison with fully homomorphic encryption algorithms, it is more efficient and practical. The hash-based index is based on the ElGamal additive homomorphic encryption algorithm using an elliptic curve. Moreover, this scheme addresses privacy concerns faced within keyword-based searching mechanisms by employing the ElGamal additive homomorphic encryption for implementing a ranked searching scheme that returns top-\(k\) files for a keyword query request. The TF-IDF weights used in the ranked searching scheme are added up using the ElGamal additive homomorphic encryption. Moreover, the authors also employ dummy keywords in the list of common words for the files to resist keyword guessing attacks, either by a cloud server or any outer adversary. Finally, the authors employ a binary search tree to make the file searching more efficient.