International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Initiator-Resilient Universally Composable Key Exchange

Dennis Hofheinz
Jörn Müller-Quade
Rainer Steinwandt
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Abstract: Key exchange protocols in the setting of universal composability are investigated. First we show that the ideal functionality F_KE of [CK02] cannot be realized in the presence of adaptive adversaries, thereby disproving a claim in [CK02]. We proceed to propose a modification F_KE^(i,j), which is proven to be realizable by two natural protocols for key exchange. Furthermore, sufficient conditions for securely realizing this modified functionality are given. Two notions of key exchange are introduced that allow for security statements even when one party is corrupted. Two natural key exchange protocols are proven to fulfill the "weaker" of these notions, and a construction for deriving protocols that satisfy the "stronger" notion is given.
  title={Initiator-Resilient Universally Composable Key Exchange},
  booktitle={IACR Eprint archive},
  keywords={cryptographic protocols / formal cryptography, cryptographic protocols, universal composition, key exchange},
  note={Published in Proceedings of ESORICS 2003, Springer LNCS 2808. 12381 received 8 Apr 2003, last revised 25 Nov 2003},
  author={Dennis Hofheinz and Jörn Müller-Quade and Rainer Steinwandt},