Apr 9,1997
Markus Jakobsson
Privacy vs. Authenticity

Speaker: Markus Jakobsson, University of California, San Diego

Title: Privacy vs. Authenticity

Abstract:

In many cryptographic settings, there is a trade-off between privacy and authenticity. This talk focuses on this trade-off in the context of electronic commerce: On one hand, we have schemes whose perfect and un-revokable privacy makes them susceptible to attacks such as blackmail and money-laundry. On the other hand, we have schemes where the authenticity of the funds (in the sense of ownership) is guaranteed by sacrificing user privacy in its entirety. We propose a model and protocols balancing the needs for privacy against those of authenticity.

In our proposed e-money system, all users enjoy full privacy, but both value of funds and user anonymity can be revoked or suspended unconditionally, by the cooperation of a quorum of banks and consumer rights organizations. Our method employs diffusion of a task into distributed modules; doing so, it enables a stronger and more realistic adversarial setting, and achieves increased security, privacy, availability and functionality without introducing any noticeable disadvantage. The result is a scheme that protects against privacy aided attacks, such as blackmail and money-laundry, as well as the ``ultimate crime,'' where an active attacker gets the bank's secret key or forces the bank to give ``unmarked bank notes''. Our system, unlike all previous anonymous systems, can prevent such a crime from successfully being perpetrated, and employs revocation to do so.

The mechanisms introduced to balance the need for anonymity against the need to be able to revoke it, together with the notion of challenge semantics that we introduce, provide us with a very versatile system, a second important goal of our investigation. The proposed scheme is efficient and allows for numerous modes of payments.

Biography:

Markus Jakobson is currently a Post Doctoral Research Fellow at the San Diego Supercomputer Center where he performs research on the application of cryptographic techniques including electronic money and payment systems. He holds a Phd from the University of California, San Diego and a Masters from the Lund Institute of Technology (Sweden).

Contact:

Markus Jakobsson
Department of Comptuer Science and Engineering
University of California, San Diego
La Jolla, CA 92093=0114
(619) 534-8847 work
(619) 534-7029 fax
markus@cs.ucsd.edu

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