A BGN-Type Multiuser Homomorphic Encryption Scheme

Abstract

Homomorphic encryption(HE) is a new cryptographic primitive that can operate on ciphertext without decryption. It has significant application in cloud computing. However, most of the existing HE schemes are single user, which means they could only evaluate on ciphertext encrypted by a single public key. Combining the idea of proxy re-encryption and homomorphic encryption, we provide a BGN-type multi-user HEscheme that can evaluate on ciphertexts come from different users. The scheme is based on bilinear pairing and subgroup decision problem, and is a somewhat homomorphic scheme that can do one multiplication and infinite additions. Security of the scheme is based on the subgroup decision assumption.