Generalized Anonymous Broadcast Encryption Scheme

Abstract

In this paper, we propose an identity-based, generalized, anonymous broadcast encryption scheme. Due to its anonymity property, this scheme can be used in a large scale medical database, in which every medical record is dynamically assigned access right to multiple users. First, we design a mechanism to conceal the broadcast target receivers for Boneh and Hamburg's ”Spatial Encryption” scheme. This mechanism hides the policy vector using the receiver's identity and system's public parameters. Everyone in the target receiver set can decrypt the ciphertext, while others learn neither the message nor the identities of the target receivers. We define the security notion for this anonymous broadcast encryption system. Assuming that BDDHE problem is intractable, we prove the security of the proposed scheme without random oracles.