8th European Symposium on Research in Computer Security (ESORICS 2003)
Initiator-Resilient Universally Composable Key Exchange
Dennis Hofheinz, Jörn Müller-Quade, Rainer Steinwandt
Keywords : formal cryptography, cryptographic protocols, universal composition, key exchange
Abstract : Key exchange protocols in the setting of universal composability are investigated. First we show that the ideal functionality of  cannot be realized in the presence of adaptive adversaries, thereby disproving a claim in . We proceed to propose a modification , 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.
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