Summary: Explicit Communication Revisited:
Two New Attacks on Authentication Protocols
Mart'in Abadi
Systems Research Center
Digital Equipment Corporation
ma@pa.dec.com
March 9, 1997
Abstract
SSH and AKA are recent, practical protocols for secure connections
over an otherwise unprotected network. This paper shows that, despite
the use of public­key cryptography, SSH and AKA do not provide
authentication as intended. The flaws of SSH and AKA can be viewed
as the result of their disregarding a basic principle for the design of
sound authentication protocols: the principle that messages should be
explicit.
1 Introduction
SSH and AKA are two recent, practical protocols for secure connections over
an otherwise unprotected network [Yl¨o96a, SSH96]; for example, they enable
users to log into remote hosts. Both of the protocols rely on public­key
cryptography for authentication (specifically, on RSA [RSA78]). In addition

Source: Abadi, Martín - Department of Computer Science, University of California at Santa Cruz

Collections: Computer Technologies and Information Sciences