Geoffrey Smith

Research Profile

Dr. Geoffrey Smith’s research is focused on the foundations of computer security. For many years, he has studied the secure information flow problem, which aims to prevent confidential information from being leaked, and trusted information from being tainted. His 1996 paper [6] showed that secure information flow could be guaranteed through the use of a novel type system; this approach was extended to multi-threaded programs in his 1998 paper [5]. These papers have been important in initiating the area of language-based security; they have been cited 776 and 403 times, respectively, according to Google Scholar.

But while one might want to prevent improper flows completely, it has long been recognized that perfection is often impossible in practice. A basic example is a login program: whenever it rejects an incorrect password, it unavoidably reveals that the secret password differs from the one that was entered. More subtly, systems may be vulnerable to side channel attacks, because observable characteristics like running time and power consumption may depend, at least partially, on sensitive information.

For this reason, since 2008 Geoffrey has focused on Quantitative Information Flow, which aims to justify the intuition that certain improper flows can be tolerated on the grounds that they are “small”. His 2009 paper [4] challenged the prevailing belief that information flow should be measured using Shannon entropy and mutual information, proposing instead to use a version of min-entropy; this paper has received considerable interest, having been cited 113 times according to Google Scholar. His 2010 paper [3] showed rigorous min-entropy leakage bounds for timing attacks against RSA cryptography with blinding. And his 2012 paper [2] proposed a rich generalization of min-entropy leakage, using gain functions to specify a wide range of operational scenarios. His current interests are centered on the mathematical theory of quantitative leakage measures and on static analyses for analyzing leakage in software.

Recent Accomplishments

  • Funding
    • Geoffrey Smith, PI, TC:Small: Theory and Applications of Min-Entropy Leakage, NSF CNS-1116318, August 2011 to July 2014, $512,000.
    • Geoffrey Smith, PI, CT-ISG: New Foundations for Quantitative Information Flow, NSF CNS-0831114, September 2008 to August 2012, $336,000.


  • Collaborations
    • Visiting Scientist, Laboratoire d’Informatique, Ecole Polytechnique, Palaiseau, France
    • Distinguished Visiting Researcher, IMDEA Software, Madrid, Spain
    • Partner, INRIA Associate Team PRINCESS, with researchers at INRIA Saclay and University of Pennsylvania


  • Co-editor, special issue of Mathematical Structures in Computer Science on Quantitative Information Flow


  • Invited speaker, QEST 2011 (8th International Conference on Quantitative Evaluation of SysTems), Aachen, Germany


  • Program Committee member: QEST 2012, ESOP 2013, FORTE/FMODS 2013, CONCUR 2013

Selected Publications

  1. Barbara Espinoza and Geoffrey Smith, Min-Entropy as a Resource, accepted to Information and Computation (Special Issue on Information Security as a Resource), October 2012.
  2. Mário S. Alvim, Kostos Chatzikokolakis, Catuscia Palamidessi, and Geoffrey Smith, Measuring Information Leakage using Generalized Gain Functions, Proc. CSF 2012: 25th IEEE Computer Security Foundations Symposium, pp. 265–279, Harvard University, Cambridge, MA, June 2012.
  3. Boris Köpf and Geoffrey Smith, Vulnerability Bounds and Leakage Resilience of Blinded Cryptography under Timing Attacks, Proc. CSF 2010: 23rd IEEE Computer Security Foundations Symposium, pp. 44–56, Edinburgh, UK, July 2010.
  4. Geoffrey Smith, On the Foundations of Quantitative Information Flow, Proc. FoSSaCS 2009: Twelfth International Conference on Foundations of Software Science and Computation Structures, Luca de Alfaro (Ed.), LNCS 5504, pp. 288–302, York, UK, March 2009.
  5. Geoffrey Smith and Dennis Volpano, Secure Information Flow in a Multi-threaded Imperative Language, Proc. POPL 1998: 25th ACM Symposium on Principles of Programming Languages, pp. 355-364, San Diego, California, January 1998.
  6. Dennis Volpano, Geoffrey Smith, and Cynthia Irvine, A Sound Type System for Secure Flow Analysis, Journal of Computer Security, vol. 4, nos. 2,3, December 1996, pp. 167–187.
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