[HGI-News-de] HGI Seminar Fr. 11. Apr.13.00 Uhr: " Perf. Secure Password Protocols in the BR Model" von G. Di Creszenzo

[Newsletter des Horst Görtz Instituts]

Hallo,


im Rahmen des HGI-Seminars "Aktuelle Themen der IT-Sicherheit" wird  
am kommenden Freitag ein unser Gast Giovanni Di Crescenzo vortragen.
Beachten Sie bitte die *geänderte Zeit und Raum* (wegen des Extra-Termins)!

*Giovanni Di Crescenzo (Telcordia Research, NJ,USA):
"Perfectly Secure Password Protocols in the Bounded Retrieval Model "


Freitag, den 11. April um  13.00 Uhr
Raum: IC 4/39-41.*

Alle Interessierte sind herzlich eingeladen!


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Abstract:

We introduce a formal model, which we call the /Bounded Retrieval Model/, 
for the design and analysis of cryptographic protocols remaining secure against intruders that can retrieve a limited amount of parties' private memory. The underlying model assumption on the intruders' behavior is supported by real-life physical and logical considerations, such as the inherent superiority of a party's local data bus over a /remote/ intruder's bandwidth-limited channel, or the detectability of voluminous resource access by any /local/ intruder. More specifically, we assume a fixed upper bound on the amount of a party's storage retrieved by the adversary. Our model could be considered a non-trivial variation of the well-studied Bounded Storage Model, which postulates a bound on the amount of storage available to an adversary attacking a given system. 
In this model we study perhaps the simplest among cryptographic 
tasks: user authentication via a password protocol. Specifically, we study the problem of constructing efficient password protocols that remain secure against offline dictionary attacks even when a large (but bounded) part of the storage of the server responsible for password verification is retrieved by an intruder through a remote or local connection. We show password protocols having satisfactory performance on both /efficiency/ (in terms of the server's 
running time) and /provable security/ (making the offline dictionary attack 
not significantly stronger than the online attack). We also study the tradeoffs between efficiency, quantitative and qualitative security in these protocols. 
All our schemes achieve /perfect security/ (security against 
computationally-unbounded adversaries). Our main schemes achieve the interesting efficiency property of the server's lookup complexity being much smaller than the adversary's retrieval bound.

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Informationen über die nächsten geplannten Vorträge im Rahmen des
HGI-Seminars sind auch im Web zu finden:
http://www.hgi.rub.de/deutsch/lehrangebot/seminar/ws200708.html

Gruß,

Biljana Cubaleska