Cryptology ePrint Archive: Report 2008/413

Password Mistyping in Two-Factor-Authenticated Key Exchange

Vladimir Kolesnikov and Charles Rackoff

Abstract: Abstract: We study the problem of Key Exchange (KE), where authentication is two-factor and based on both electronically stored long keys and human-supplied credentials (passwords or biometrics). The latter credential has low entropy and may be adversarily mistyped. Our main contribution is the first formal treatment of mistyping in this setting.

Ensuring security in presence of mistyping is subtle. We show mistyping-related limitations of previous KE definitions and constructions.

We concentrate on the practical two-factor authenticated KE setting where servers exchange keys with clients, who use short passwords (memorized) and long cryptographic keys (stored on a card). Our work is thus a natural generalization of Halevi-Krawczyk and Kolesnikov-Rackoff. We discuss the challenges that arise due to mistyping. We propose the first KE definitions in this setting, and formally discuss their guarantees. We present efficient KE protocols and prove their security.

Category / Keywords: foundations / Key exchange, definition, combined keys, password, biometric

Publication Info: ICALP 2008

Date: received 28 Sep 2008, last revised 8 Oct 2008

Contact author: kolesnikov at research bell-labs com

Available format(s): Postscript (PS) | Compressed Postscript (PS.GZ) | PDF | BibTeX Citation

Note: This revision fixes a broken pdf file. No content changes.

Version: 20081008:171758 (All versions of this report)

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