Attribute Based Search in Encrypted Data: ABSE

Searchable encryption enables users to delegate search functionalities to third-parties without giving them the ability to decrypt. Existing schemes assume that the sender knows the identity of the receiver. In this paper we relax this assumption by proposing the first Attribute Based Searchable Encryption Scheme (ABSE). An ABSE is a type of public key encryption with keyword search that allows the user encrypting the data to specify a policy that determines, among the users of the system, who is eligible to decrypt and search the data. Each user of the system owns a set of attributes and the policy is a function of these attributes expressed as a predicate. Only members who own sufficient attributes to satisfy that policy can send the server a valid search query. In our work we introduce the concept of a secure ABSE by defining the functionalities and the relevant security notions such as correctness, chosen keyword attacks, and attribute forgeability attacks. Our definitions are based on provable security formalizations. We further propose a secure construction of an ABSE based on bilinear maps. We illustrate the use of our proposed scheme in a shared storage for medical records.