On Robust Key Agreement Based on Public Key Authentication

We describe two new attacks on the HMQV protocol. The first attack raises a serious question on the basic definition of "authentication" in HMQV, while the second attack is generally applicable to many other protocols. In addition, we present a new authenticated key agreement protocol called YAK. Our approach is to depend on well-established techniques such as Schnorr's signature. Among all the related protocols, YAK appears to be the simplest so far. We believe simplicity is an important engineering principle.