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Author Katz, Jonathan ♦ Ostrovsky, Rafail ♦ Yung, Moti
Source ACM Digital Library
Content type Text
Publisher Association for Computing Machinery (ACM)
File Format PDF
Copyright Year ©2009
Language English
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword Authentication ♦ Cryptography ♦ Passwords
Abstract Mutual authentication and authenticated key exchange are fundamental techniques for enabling secure communication over public, insecure networks. It is well known how to design secure protocols for achieving these goals when parties share $\textit{high-entropy}$ cryptographic keys in advance of the authentication stage. Unfortunately, it is much more common for users to share weak, $\textit{low-entropy}$ passwords which furthermore may be chosen from a known space of possibilities (say, a dictionary of English words). In this case, the problem becomes much more difficult as one must ensure that protocols are immune to off-line dictionary attacks in which an adversary exhaustively enumerates all possible passwords in an attempt to determine the correct one. We propose a 3-round protocol for password-only authenticated key exchange, and provide a rigorous proof of security for our protocol based on the decisional Diffie-Hellman assumption. The protocol assumes only public parameters—specifically, a “common reference string”—which can be “hard-coded” into an implementation of the protocol; in particular, and in contrast to some previous work, our protocol does $\textit{not}$ require either party to pre-share a public key. The protocol is also remarkably efficient, requiring computation only (roughly) 4 times greater than “classical” Diffie-Hellman key exchange that provides no authentication at all. Ours is the first protocol for password-only authentication that is both $\textit{practical}$ and provably-secure using standard cryptographic assumptions.
ISSN 00045411
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2009-11-01
Publisher Place New York
e-ISSN 1557735X
Journal Journal of the ACM (JACM)
Volume Number 57
Issue Number 1
Page Count 39
Starting Page 1
Ending Page 39


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Source: ACM Digital Library