Constructing Forward-Secure Identity-Based Encryption from Identity-Based Binary Tree Encryption

In this paper, we propose a generic construction of forward-secure identity-based encryption. We first introduce a relaxed variant of hierarchical identity-based encryption called identity-based binary tree encryption and construct a concrete identity-based binary tree encryption scheme which is provably secure in the standard model. We then show that forward-secure identity-based encryption can be generically constructed from identity-based binary tree encryption. Based on the proposed identity-based binary tree encryption scheme, we obtain a direct chosen-ciphertext secure forward-secure identity-based encryption scheme without random oracles.