Paper 2008/001

Security Proof for the Improved Ryu-Yoon-Yoo Identity-Based Key Agreement Protocol

Shengbao Wang, Zhenfu Cao, Kim-Kwang Raymond Choo, and Lihua Wang


Key agreement protocols are essential for secure communications in open and distributed environments. The protocol design is, however, extremely error-prone as evidenced by the iterative process of fixing discovered attacks on published protocols. We revisit an efficient identity-based (ID-based) key agreement protocol due to Ryu, Yoon and Yoo. The protocol is highly efficient and suitable for real-world applications despite offering no resilience against key-compromise impersonation (K-CI). We then show that the protocol is, in fact, insecure against reflection attacks. A slight modification to the protocol is proposed, which results in significant benefits for the security of the protocol without compromising on its efficiency. Finally, we prove the improved protocol secure in a widely accepted model.

Note: In this paper, the security of the ID-based version of the famous UMP protocol is studied.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Unknown where it was published
key agreement protocolmodular security proof
Contact author(s)
shengbaowang @ gmail com
2008-01-03: received
Short URL
Creative Commons Attribution


      author = {Shengbao Wang and Zhenfu Cao and Kim-Kwang Raymond Choo and Lihua Wang},
      title = {Security Proof for the Improved Ryu-Yoon-Yoo Identity-Based Key Agreement Protocol},
      howpublished = {Cryptology ePrint Archive, Paper 2008/001},
      year = {2008},
      note = {\url{}},
      url = {}
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