Secure searches in the cloud: A survey

•Comprehensive survey on searchable encryption for cloud security.•A new classification of searchable encryption applicable to cloud security.•Open and future research directions and questions.

Cloud security is a huge concern when users and enterprises consider to deploy cloud computing services. This article mainly presented an important aspect of cloud security which is called searchable encryption. Searchable encryption is a scheme that enable users to secure search on encrypted data stored in cloud. To guarantee privacy of users’ data, users encrypt their data files before uploading, then when they need to fetch some files, they can use searchable encryption to execute keyword search on encrypted data. Searchable encryption can be classified by three models, each is corresponding with different application scenario. Two of them are suitable with cloud architecture. They are called searchable public key encryption and searchable symmetric encryption respectively. Searchable public key encryption is mainly for data sharing scenario. A user wants to share some data files with other users privately. He can encrypt these files with receivers’ public key. And receivers can securely search on it with their private keys. Searchable symmetric encryption can enable users securely using their online storage. They can upload data files which are encrypted with their secret keys. And then they can securely search on these encrypted data with the secret key no matter when and where they are.