Attack on the Koyama-Ohta Identity Based Key Distribution Scheme

  • Yacov Yacobi
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 293)


Koyama and Ohta proposed an identity based key distribution scheme. They considered three configurations: ring, complete graph, and star. The most practical configuration is the star which is used in teleconferencing. We show the Koyama-Ohta star scheme to be insecure. Specifically, we show that an active eavesdropper may cut one of the lines, and perform a bidirectional impersonation, thus establishing two separate keys. One with each side.


  1. [I]
    K. Koyama and K. Ohta:“Identity based conference key distribution systems”, To appear in the proceedings of Crypto-87Google Scholar
  2. [2]
    Diffie and Hellman: “New Directions in Cryptography”, IEEE Trans. on Inf. Th., 1976.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1988

Authors and Affiliations

  • Yacov Yacobi
    • 1
  1. 1.Bell Communications ResearchMorristownUSA

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