Paper 2019/299

A Generic Construction of Revocable Identity-Based Encryption

Xuecheng Ma and Dongdai Lin

Abstract

Revocable identity-based encryption (RIBE) is an extension of IBE that supports a key revocation mechanism, which is important when deployed an IBE system in practice. Boneh and Franklin presented the first generic construction of RIBE, however, their scheme is not scalable where the size of key update is linear in the number of users in the system. Then, Boldyreva, Goyal and Kumar presented the first scalable RIBE where the size of key update is logarithmic in the number of users and linear in the number of revoked users. In this paper, we present a generic construction of scalable RIBE from any IBE in a black-box way. Our construction has some merits both in theory and in practice. We obtain the first RIBE scheme based on quadratic residuosity problem and the first adaptively secure RIBE scheme based on lattices if we instantiate the underlying IBE with IBE schemes from quadratic residuosity assumption and adaptively secure IBE from lattices, respectively. In addition, the size of public parameters and secret keys are the same as that of the underlying IBE schemes. In server-aided model, the overheads of communication and computation for receivers are the same as those of underlying IBE schemes. Furthermore, the storage overhead for key update in our scheme is constant (in the number of users) while it was linear in the number of users in previous works.