Do not ask me what I am looking for: Index deniable encryption

In this network era, the cloud storage service has become increasingly important. People have become used to storing data on the cloud and accessing them anytime, anywhere. However, due to privacy issues, data should be encrypted before being uploaded to the cloud. Thus, determining how to obtain the designated data from ciphertexts is important. In recent years, numerous searchable encryption schemes have been proposed. Most of these schemes do not consider the case wherein the search behavior is monitored, and there may come a time when users will be forced to open their search records and results. Thus, in this paper, an index deniable encryption scheme that supports both searchability and deniability is proposed to ensure user privacy in the cloud storage and the outside coercion case. We integrate the Bloom filter and the CP-ABE technique to construct a searchable encryption scheme. With the redundant keyword design, the search result can be opened to a fake data for the outside coercer. The proposed work has a constant ciphertext size to multiple deniable possibilities.