[Seth-Trips] Matt Blaze on wiretapping at Stanford, Wednesday

Seth David Schoen schoen at loyalty.org
Mon Mar 6 15:16:28 PST 2006

(I expect to go to this.)


03.08.2006 	16:15 - 17:30
Gates B01

EE380 CSL - Colloquium
Matt Blaze, Associate Professor of Computer and Information
Science, University of Pennsylvania — Signaling Vulnerabilities
in Law-Enforcement Wiretap Systems

About the talk:
Telephone wiretap and dialed number recording systems are used by law
enforcement and national security agencies to collect investigative
intelligence and legal evidence. This talk will show how many of these
systems are vulnerable to simple, unilateral countermeasures that allow
wiretap targets to prevent their call audio from being recorded and/or
cause false or inaccurate dialed digits and call activity to be logged.
The countermeasures exploit the unprotected in-band signals passed
between the telephone network and the collection system and are
effective against many of the wiretapping technologies currently used by
US law enforcement, including at least some ``CALEA'' systems. Possible
remedies and workarounds will be proposed, and the broader implications
of the security properties of these systems will be discussed.

A recent paper, as well as audio examples of several wiretapping
countermeasures, can be found at

This is joint work with Micah Sherr, Eric Cronin, and Sandy Clark.

Speaker Bio:
Research: Prof Blaze's research focuses on the architecture and design
of secure systems based on cryptographic techniques, analysis of secure
systems against practical attack models, and on finding new
cryptographic primitives and techniques. This work has led directly to
several new cryptographic concepts, including: "Remotely-Keyed
Encryption," which allows the use of inexpensive, low-bandwidth secure
hardware to protect high-bandwidth communication and stored data,
"Atomic Proxy Cryptography," which allows re-encryption by untrusted
third parties, and "Master-Key Encryption," which provides a systematic
way to design (and study) ciphers with built-in "back doors."

Prof Blaze is especially interested in the use of encryption to protect
insecure systems such as the Internet. He was a designer of swIPe, a
predecessor of the now standard IPSEC protocol for protecting Internet
traffic. Another project, CFS, investigated and demonstrated the
feasibility of including encryption as file system service.

Seth David Schoen <schoen at loyalty.org> | This is a new focus for the security
     http://www.loyalty.org/~schoen/   | community. The actual user of the PC
     http://vitanuova.loyalty.org/     | [...] is the enemy.
                                       |          -- David Aucsmith, IDF 1999

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