International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Security Analysis of KEA Authenticated Key Exchange Protocol

Kristin E. Lauter
Anton Mityagin
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Abstract: KEA is a Diffie-Hellman based key-exchange protocol developed by NSA which provides mutual authentication for the parties. It became publicly available in 1998 and since then it was neither attacked nor proved to be secure. We analyze the security of KEA and find that the original protocol is susceptible to a class of attacks. On the positive side, we present a simple modification of the protocol which makes KEA secure. We prove that the modified protocol, called KEA+, satisfies the strongest security requirements for authenticated key-exchange and that it retains some security even if a secret key of a party is leaked. Our security proof is in the random oracle model and uses the Gap Diffie-Hellman assumption. Finally, we show how to add a key confirmation feature to KEA+ (we call the version with key confirmation KEA+C) and discuss the security properties of KEA+C.
  title={Security Analysis of KEA Authenticated Key Exchange Protocol},
  booktitle={IACR Eprint archive},
  keywords={cryptographic protocols /},
  note={To appear at PKC 2006 13196 received 12 Aug 2005, last revised 16 Feb 2006},
  author={Kristin E. Lauter and Anton Mityagin},