Making Any Attribute-Based Encryption Accountable, Efficiently

Attribute-based encryption (ABE) as one of the most interesting multi-recipient public encryption systems, naturally requires some "tracing mechanisms" to identify misbehaving users to foster accountability when unauthorized key re-distributions are taken place. We give a generic construction of (black-box) traceable ABE which only doubles the ciphertext size of the underlying ABE scheme. When instantiating properly, it yields the first such scheme with constant size ciphertext and expressive access control. Furthermore, we extend our generic construction of traceable ABE to support authority accountability. This property is essential for generating an un-deniable proof for user misbehaviors. Our new generic construction gives the first black-box traceable ABE with authority accountability, and constant size ciphertext. All properties are achieved in standard security models.