Refinement and extension of encrypted key exchange

ABSTRACT

In their recent paper, "Encrypted Key Exchange: Password-based Protocols Secure Against Dictionary Attacks," Bellovin and Merritt propose a novel and elegant method for safeguarding weak passwords. This paper discusses a possible weakness in the proposed protocol, develops some enhancements and simplifications, and provides a security analysis of the resultant minimal EKE protocol. In addition, the basic 2-party EKE model is extended to the 3-party setting; this yields a protocol with some interesting properties. Most importantly, this paper illustrates, once again, the subtlety associated with designing password-based protocols.

REFERENCES

• 1: Steven M. Bellovin , Michael Merritt, Encrypted Key Exchange: Password-Based Protocols SecureAgainst Dictionary Attacks, Proceedings of the 1992 IEEE Symposium on Security and Privacy, p.72, May 04-06, 1992
• 2: Steven M. Bellovin , Michael Merritt, Augmented encrypted key exchange: a password-based protocol secure against dictionary attacks and password file compromise, Proceedings of the 1st ACM conference on Computer and communications security, p.244-250, November 03-05, 1993, Fairfax, Virginia, United States [doi>10.1145/168588.168618]
• 3: Mihir Bellare , Phillip Rogaway, Entity authentication and key distribution, Proceedings of the 13th annual international cryptology conference on Advances in cryptology, p.232-249, January 1994, Santa Barbara, California, United States
• 4: [4] M. Burrows, M. Abadi and R. Needham, A Logic of Authentication Technical Report 39, DEC System Research Center, February 1990.
• 5: Dorothy E. Denning , Giovanni Maria Sacco, Timestamps in key distribution protocols, Communications of the ACM, v.24 n.8, p.533-536, Aug. 1981 [doi>10.1145/358722.358740]
• 6: [6] W. Diffie and M. Hellman, New Directions in Cryptography, IEEE Transactions on Information Theory, November 1976.
• 7: Li Gong, Lower bounds on messages and rounds for network authentication protocols, Proceedings of the 1st ACM conference on Computer and communications security, p.26-37, November 03-05, 1993, Fairfax, Virginia, United States [doi>10.1145/168588.168592]
• 8: [8] National Bureau of Standards, Federal Information Processing Standards, National Bureau of Standards, Publication 46, 1977.
• 9: Roger M. Needham , Michael D. Schroeder, Using encryption for authentication in large networks of computers, Communications of the ACM, v.21 n.12, p.993-999, Dec. 1978 [doi>10.1145/359657.359659]
• 10: R M Needham , M D Schroeder, Authentication revisited, ACM SIGOPS Operating Systems Review, v.21 n.1, p.7-7, Jan. 1987 [doi>10.1145/24592.24593]
• 11: R. Rivest, The MD5 Message-Digest Algorithm, RFC Editor, 1992
• 12: [12] B. Schneier, Applied Cryptography (Section 12.2), New York, NY: Wiley, 1994.
• 13: D. W. Davies , W. L. Price, Security for computer networks: and introduction to data security in teleprocessing and electronic funds transfer (2nd ed.), John Wiley & Sons, Inc., New York, NY, 1989
• 14: [14] W. Mao and C. Boyd, Cryptographic Key Establishment Secure Against Exhaustive Key Search DRAFT, submitted to 1995 IEEE Symposium on Research in Security and Privacy, available from [e-mail], Fall 1994.

INDEX TERMS

Primary Classification:
  K. Computing Milieux
  K.1 THE COMPUTER INDUSTRY
      Subjects: Standards

Additional Classification:
  D. Software
  D.4 OPERATING SYSTEMS

  E. Data
  E.3 DATA ENCRYPTION

  K. Computing Milieux
  K.6 MANAGEMENT OF COMPUTING AND INFORMATION SYSTEMS

General Terms:
Design, Management, Performance, Security, Standardization, Theory