Talk: Matt Blaze on “Signaling Vulnerabilities in Law-Enforcement Wiretap Systems”

For folks local to the Bay Area, Prof. Matt Blaze is speaking next week at Stanford on vulnerabilities in the systems currently being used by law enforcement for wiretapping. The talk is at 4:15PM next Wednesday, 3/8/06 at Stanford University’s HP Auditorium, Gates Computer Science Building B01.

Signaling Vulnerabilities in Law-Enforcement Wiretap Systems
Matt Blaze, University of Pennsylvania

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.

(Thanks to Mort for the link!)