Homomorphic encryption in the attribute-based setting

Abstract

The main research question addressed by this thesis is whether we can combine a cryptographic primitive called homomorphic encryption with a cryptographic primitive called attribute based encryption. Firstly, let us define both homomorphic encryption and attribute based encryption. Homomorphic Encryption (HE) involves the ability to operate on encrypted data without knowing the secret key. Attribute Based Encryption (ABE) provides fine grained access control over data by allowing an entity to encrypt data with attributes which must be satisfied by a decryptor’s access policy in order for decryption to succeed. A special case of ABE is identity-based encryption (IBE) where the access policies are simple equality relations i.e. each access policy is satisfied by a singular attribute.