Predicate-Based Key Exchange
We provide the first description of and security model for authenticated key exchange protocols with predicate-based authentication. In addition to the standard goal of session key security, our security model also provides for credential privacy: a participating party learns nothing more about the other party's credentials than whether they satisfy the given predicate. Our model also encompasses attribute-based key exchange since it is a special case of predicate-based key exchange. We demonstrate how to realize a secure predicate-based key exchange protocol by combining any secure predicate-based signature scheme with the basic Diffie-Hellman key exchange protocol, providing an efficient and simple solution.
Relations Among Notions of Plaintext Awareness
We introduce a new simplified notion of plaintext awareness, which we term PA2I, and show that this is equivalent to the standard definition of PA2 plaintext awareness for encryption schemes that satisfy certain weak security and randomness requirements. We also show that PA2 plaintext awareness is equivalent to PA2+ plaintext awareness under similar security and randomness requirements. This proves a conjecture of Dent that, for suitably random public-key encryption schemes, PA2 plaintext awareness implies PA1+ plaintext awareness.
Efficient Chosen-Ciphertext Secure Identity-Based Encryption with Wildcards
We propose new instantiations of chosen-ciphertext secure identity-based encryption schemes with wildcards (WIBE). Our schemes outperform all existing alternatives in terms of efficiency as well as security. We achieve these results by extending the hybrid encryption (KEM--DEM) framework to the case of WIBE schemes. We propose and prove secure one generic construction in the random oracle model, and one direct construction in the standard model.