Cryptography, Security, and Privacy (CrySP)

This speaker series is made possible by an anonymous charitable donation in memory of cypherpunks and privacy advocates Len Sassaman, Hugh Daniel, Hal Finney, and Caspar Bowden.

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Security and Privacy of Legally Authorized Telephone Surveillance

Micah Sherr, Georgetown University

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August 2, 2012 1:30pm, in DC 2585


In many democratic countries, law enforcement agencies conduct wiretaps to gather intelligence and collect evidence for legal procedures. This talk examines the security and privacy properties of these legally authorized telephone surveillance systems, and demonstrates how implementation and architectural weaknesses in popular wiretap systems may lead to inaccuracies in wiretap transcripts.

Given the architectural weaknesses of modern wiretap systems and the impractical costs associated with re-engineering significant portions of the telecommunications infrastructure, this talk also presents a lightweight "accountable wiretapping" system for enabling secure audits of existing CALEA wiretapping systems. Our proposed system maintains a tamper-evident encrypted log over wiretap events, enforces access controls over wiretap records, and enables privacy-preserving aggregate queries and compliance checks. We demonstrate using campus-wide telephone trace data from a large university that our approach provides efficient auditing functionality while incurring only modest overhead.

This talk describes joint work with Matt Blaze, Kevin Butler, Sandy Clark, Eric Cronin, Gaurav Shah, Clay Shields, Patrick Traynor, and Dan Wallach.


Micah Sherr is an assistant professor in the Computer Science Department at Georgetown University. His academic interests include privacy-preserving technologies, electronic voting, wiretap systems, and network security. Prior to arriving at Georgetown, he participated in two large-scale studies of electronic voting machine systems, and helped to disclose numerous architectural vulnerabilities in U.S. election systems. His current research examines the security properties of legally authorized wiretap (interception) systems and investigates methods for achieving scalable, high-performance anonymous routing. Micah received his B.S.E., M.S.E., and Ph.D. degrees from the University of Pennsylvania. He is a recipient of the NSF CAREER award.