Searchable encryption on the cloud: a survey

Outsourcing data to the cloud can be considered as a perfect solution for the storage and computationally constrained data owners. However, data confidentiality is compromised when data are shared through the cloud. Cryptographic techniques like searchable encryption offer possible solutions of protect data from unauthorized access while facilitating searching without disclosure. Different searchable encryption techniques have been proposed; however, the techniques are limited in one way or the other, and none of them satisfies all the needs of confidentiality while sharing of data outsourced on the cloud. In this survey, we have identified the key performance indicators for confidentiality while sharing for cloud data along with possible attacks on searchable encryption techniques. A comprehensive study of the existing techniques searchable encryption on the anvil of the key performance indicators and robustness to attacks has been done. It was found that a technique may be suitable for an application with specific data confidentiality requirements, although no cryptographic silver bullet exists that satisfies all the performance metrics or is impervious to all the attacks. Moreover, most of the existing techniques are impracticable due to paradoxical requirements of data confidentiality and performance. A single mechanism may not suffice, and there is a need for a basket of efficient techniques that may provide accurate search with data confidentiality to make data sharing over the cloud an economically attractive option.