N-party encrypted diffie-hellman key exchange using different passwords

Jin Wook Byun, Dong Hoon Lee

Research output: Chapter in Book/Report/Conference proceedingConference contribution

28 Citations (Scopus)


We consider the problem of password-authenticated group Diffie-Hellman key exchange among N parties, N-1 clients and a single-server, using different passwords. Most password-authenticated key exchange schemes in the literature have focused on an authenticated key exchange using a shared password between a client and a server. With a rapid change in modern communication environment such as ad-hoc networks and ubiquitous computing, it is necessary to construct a secure end-to-end channel between clients, which is a quite different paradigm from the existing ones. To achieve this end-to-end security, only a few schemes of three-party setting have been presented where two clients exchange a key using their own passwords with the help of a server. However, up until now, no formally treated and round efficient protocols which enable group members to generate a common session key with clients' distinct passwords have been suggested. In this paper we securely and efficiently extend three-party case to N-party case with a formal proof of security. Two provably secure N-party EKE protocols are suggested; N-party EKE-U in the unicast network and N-party EKE-M in the multicast network. The proposed N-party EKE-M is provable secure and provides forward secrecy. Especially, the scheme is of constant-round, hence scalable and practical.

Original languageEnglish
Title of host publicationLecture Notes in Computer Science
EditorsJ. Ioannidis, A. Keromytis, M. Yung
Number of pages16
Publication statusPublished - 2005
EventThird International Conference on Applied Cryptography and Network Security, ACNS 2005 - New York, NY, United States
Duration: 2005 Jun 72005 Jun 10


OtherThird International Conference on Applied Cryptography and Network Security, ACNS 2005
CountryUnited States
CityNew York, NY



  • Authenticated key exchange
  • Dictionary attacks
  • Different password authentication
  • Encrypted key exchange
  • N-party authentication
  • Password

ASJC Scopus subject areas

  • Computer Science (miscellaneous)

Cite this

Byun, J. W., & Lee, D. H. (2005). N-party encrypted diffie-hellman key exchange using different passwords. In J. Ioannidis, A. Keromytis, & M. Yung (Eds.), Lecture Notes in Computer Science (Vol. 3531, pp. 75-90)