Publications - Abstracts

Publications - Abstracts

Research Group of Prof.C.P.Schnorr, University of Frankfurt am Main

Incremental Cryptography and Memory Checkers

Marc Fischlin
Fachbereich Mathematik (AG 7.2) / Informatik
Johann Wolfgang Goethe-Universität Frankfurt am Main
PSF 111932
60054 Frankfurt/Main, Germany

e-mail: marc(at)

We introduce the relationship between incremental cryptography and memory checkers. We present an incremental message authentication scheme based on the XOR MACs which supports insertion, deletion and other single block operations. Our scheme takes only a constant number of pseudorandom function evaluations for each update step and produces smaller authentication codes than the tree scheme presented in [BGG95]. Furthermore, it is secure against message substitution attacks, where the adversary is allowed to tamper messages before update steps, making it applicable to virus protection. From this scheme we derive memory checkers for data structures based on lists. Conversely, we use a lower bound for memory checkers to show that so-called message substitution detecting schemes produce signatures or authentication codes with size proportional to the message length.

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Last modified: July 16, 1997