International Association for Cryptologic Research

International Association
for Cryptologic Research


Philippe Elbaz–Vincent


A New Security Model for Authenticated Key Agreement
Jean–Claude Bajard Augustin P. Sarr Philippe Elbaz–Vincent
The Canetti--Krawczyk (CK) and extended Canetti--Krawczyk (eCK) security models, are widely used to provide security arguments for key agreement protocols. We discuss security shades in the (e)CK models, and some practical attacks unconsidered in (e)CK--security arguments. We propose a strong security model which encompasses the eCK one. We also propose a new protocol, called Strengthened MQV (SMQV), which in addition to provide the same efficiency as the (H)MQV protocols, is particularly suited for distributed implementations wherein a tamper--proof device is used to store long--lived keys, while session keys are used on an untrusted host machine. The SMQV protocol meets our security definition under the Gap Diffie--Hellman assumption and the Random Oracle model.