Anonymous identity-based encryption with identity recovery

Abstract

Anonymous Identity-Based Encryption can protect privacy of the receiver. However, there are some situations that we need to recover the identity of the receiver, for example a dispute occurs or the privacy mechanism is abused. In this paper, we propose a new concept, referred to as Anonymous Identity-Based Encryption with Identity Recovery (AIBEIR), which is an anonymous IBE with identity recovery property. There is a party called the Identity Recovery Manager (IRM) who has a secret key to recover the identity from the ciphertext in our scheme. We construct it with an anonymous IBE and a special IBE which we call it testable IBE. In order to ensure the semantic security in the case where the identity recovery manager is an adversary, we define a stronger semantic security model in which the adversary is given the secret key of the identity recovery manager. To our knowledge, we propose the first AIBEIR scheme and prove the security in our defined model.