Towards modelling perfect forward secrecy in two‐message authenticated key exchange under ephemeral‐key revelation
Zheng Yang, Wu Yang, Lingyun Zhu, Daigu Zhang · Security and Communication Networks · 2015
Abstract We examine the recently introduced CF and CF‐perfect forward secrecy (PFS) models for two‐message authenticated key exchange (TMAKE) by Cremers et al., where the difference between CF and CF‐PFS model is that the CF formulates the weak PFS (wPFS), whereas the CF‐PFS formulates the PFS. The CF model is claimed by Cremers et al. to be strictly stronger the previous extended Canetti‐Krawczyk (eCK) model. However, we notice that the implication relations among CF, CF‐PFS, eCK and eCK‐PFS model have not been completely studied. Based on TMAKE, we particularly show that CF model and eCK model imply each other under random oracle model. Moreover, we provide a new result on the generic security strengthening transformation (compiler) for building CF‐PFS‐secure TMAKE protocols. In contrast to a previous work, we show that it is possible to apply the transformation to all CF‐secure AKE protocols including all eCK‐secure TMAKE protocols in the random oracle model, without restricting to a small specific class of Diffie–Hellman key based protocols. Copyright © 2015 John Wiley & Sons, Ltd.