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Constant Round Group Key Exchange with Logarithmic Computational Complexity

Authors:
Junghyun Nam
Youngsook Lee
Dongho Won
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URL: http://eprint.iacr.org/2006/284
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Abstract: Protocols for group key exchange (GKE) are cryptographic algorithms that describe how a group of parties communicating over a public network can come up with a common secret key. Due to their critical role in building secure multicast channels, a number of GKE protocols have been proposed over the years in a variety of settings. However despite many impressive achievements, it still remains a challenging problem to design a secure GKE protocol which scales very well for large groups. Our observation is that all provably-secure constant-round GKE protocols providing forward secrecy thus far are not fully scalable, but have a computational complexity that scales only linearly in group size. Motivated by this observation, we propose a new GKE protocol that not only offers full scalability in all directions but also attains provable security against active adversaries. Full scalability is achieved by using a complete binary tree structure where users are arranged on both internal and leaf nodes. Security is proved via reduction to the decisional Diffie-Hellman assumption in a well-defined formal model of communication and adversarial capabilities.
BibTeX
@misc{eprint-2006-21776,
  title={Constant Round Group Key Exchange with Logarithmic Computational Complexity},
  booktitle={IACR Eprint archive},
  keywords={cryptographic protocols / Group key exchange, scalability, binary tree, provable security, DDH assumption},
  url={http://eprint.iacr.org/2006/284},
  note={ jhnam@security.re.kr 13381 received 20 Aug 2006},
  author={Junghyun Nam and Youngsook Lee and  Dongho Won},
  year=2006
}