Nicholas J. Hopper

Assistant Professor
Computer Science & Engineering Department
University of Minnesota
hopper at cs umn edu

Office:
EECS 4-211
(612)-626-1284

Shortcuts: Research interests | Papers | Teaching | Etc...

Research

My general interests are in cryptography, computer & network security, and theoretical computer science. The focus of my research is on proving the security of computer systems and protocols. The central questions in this research are:

What should it mean for a computer system to be secure? In order to prove the security of a system or protocol we must first establish formal definitions of security.
What can we prove about the security of current systems and protocols? Given a formal security goal, it is sometimes possible to prove that existing protocols satisfy this definition or show that they do not.
How can we construct efficient systems with provable security properties? If we cannot prove the security of an existing protocol or system, a natural alternative is to construct a system so that the proof of security is tractable.

The main application areas to which my research applies these questions are privacy and anonymity and peer-to-peer systems. I have had the privilege of working on these subjects with many bright students.

Papers

Journals

Nicholas Hopper, Luis von Ahn, and John Langford. "Provably Secure Steganography," IEEE Transactions on Computers 58(5): 662-676, May 2009. (©2009 IEEE)

Nicholas Hopper, Eugene Y. Vasserman, and Eric Chan-Tin. "How much anonymity does network latency leak?" ACM Transactions on Information and System Security (TISSEC), to appear. (Accepted November 2008)

Eugene Y. Vasserman, Nicholas Hopper, and James Tyra. "SilentKnock: practical, provably undetectable authentication." International Journal of Information Security 8(2): 121-135, April 2009.

Jung Hee Cheon, Nicholas Hopper, Yongdae Kim and Ivan Osipkov. "Provably Secure Timed-Release Public Key Encryption." ACM Transactions on Information and System Security (TISSEC) 11(2):1-44, March 2008. (© 2008 ACM)

Peer-reviewed Conference/Workshops

Jon McLachlan and Nicholas Hopper. "On the risks of serving whenever you surf: Vulnerabilities in Tor's blocking resistance design," at WPES 2009.

Andrew Tran, Nicholas Hopper and Yongdae Kim. "Hashing it out in public: Common failure modes of DHT-based anonymity schemes," at WPES 2009.

Jon McLachlan, Andrew Tran, Nicholas Hopper, and Yongdae Kim. "Scalable onion routing with Torsk," at CCS 2009.

Eugene Vasserman, Rob Jansen, James Tyra, Nicholas Hopper and Yongdae Kim. "Membership-concealing overlay networks," at CCS 2009.

Eric Chan-Tin, Daniel Feldman, Yongdae Kim and Nicholas Hopper. "The Frogboiling attack: limitations of anomaly detection for secure network coordinates," at SecureComm 2009.

Hun-Jeong Kang, Eric Chan-Tin, Yongdae Kim and Nicholas Hopper. "Why Kad Lookup Fails," at P2P09.

B. Kang et al. "Towards Complete Node Enumeration in a Peer-to-Peer Botnet," at ASIACCS 2009.

P. Wang, J. Tyra, E. Chan-Tin, T. Malchow, D. Foo Kune, N. Hopper and Y. Kim. "Attacking the Kad Network," at SecureComm 2008.

Erik Shimshock, Matthew Staats, and Nicholas Hopper. "Breaking and Provably Fixing Minx," at PET 2008.

Jon McLachlan and Nicholas Hopper. "Don't Clog the Queue: Circuit Clogging and Mitigation in P2P anonymity schemes," at Financial Crypto 2008.

Nicholas Hopper, Eugene Y. Vasserman, and Eric Chan-Tin. "How much anonymity does network latency leak?" at CCS 2007.

Eugene Vasserman, Nicholas Hopper, John Laxson, and James Tyra. "SilentKnock: Practical and Provably Undetectable Authentication." at ESORICS 2007.

Ivan Osipkov, Eugene Vasserman, Nicholas Hopper and Yongdae Kim. "Combatting Double-Spending Using Cooperative P2P Systems." at ICDCS 2007.

Nicholas Hopper, David Molnar, and David Wagner. "From Weak to Strong Watermarking." at 4th Theoretical Cryptography Conference: TCC 2007. (Full version)

Nicholas Hopper and Eugene Vasserman. "On the effectiveness of k-anonymity against traffic analysis and surveillance," at Privacy in the Electronic Society: WPES 2006.

Luis von Ahn, Andrew Bortz, Nicholas Hopper, and Kevin O'Neill. "Selectively Traceable Anonymity," at Privacy Enhancing Technologies: PET 2006.

Ivan Osipkov, Peng Wang, Nicholas Hopper and Yongdae Kim. "Robust Accounting in Decentralized P2P Storage Systems," at ICDCS 2006.

Jung Hee Cheon, Nicholas Hopper, Yongdae Kim and Ivan Osipkov. "Authenticated Key-Insulated Public Key Encryption and Timed-Release Cryptography," at Financial Crypto 2006.

Nicholas Hopper. "On Steganographic Chosen Covertext Security," at ICALP 2005.

Luis von Ahn, Nicholas J. Hopper, and John Langford. "Covert Two-Party Computation," at STOC 2005.

Luis von Ahn and Nicholas J. Hopper. " Public-Key Steganography," at Eurocrypt 2004.

Luis von Ahn, Andrew Bortz, and Nicholas J. Hopper. "k-Anonymous Message Transmission," at CCS 2003.

Luis von Ahn, Manuel Blum, Nicholas J. Hopper and John Langford. " CAPTCHA: Using Hard AI Problems for Security," at Eurocrypt 2003.

Nicholas J. Hopper, John Langford, and Luis Von Ahn. " Provably Secure Steganography," at Crypto 2002.

Nicholas J. Hopper and Manuel Blum. " Secure Human Identification Protocols," at Asiacrypt 2001.

Nicholas J. Hopper, Sanjit A. Seshia, and Jeanette M. Wing, "Combining Theory Generation and Model Checking for Security Protocol Analysis," at Formal Methods in Computer Security, July 2000. Also available as CMU Technical Report CMU-CS-00-107, January 2000.

Nicholas Freitag McPhee and Nicholas J. Hopper. " Analysis of Genetic Diversity through Population History," in GECCO99: Proceedings of the Genetic and Evolutionary Computation Conference, July 1999.

Nicholas Freitag McPhee and Nicholas J. Hopper. " AppGP: An alternative structural representation for GP," in Proceedings of the 1999 Congress on Evolutionary Computation, June 1999.

Nicholas Freitag McPhee, Nicholas J. Hopper, and Mitchell L. Reierson. " Impact of types on essentially typeless problems in GP," in Genetic Programming 1998: Proceedings of the Third Annual Conference, July 1998.

In submission

Please send e-mail if you are interested in any of the following:

Peng Wang, Ivan Osipkov, Nicholas Hopper, and Yongdae Kim. "Myrmic: Provably secure and efficient DHT routing," 2007. (An earlier tech report is available here.)

Eugene Y. Vasserman and Nicholas Hopper. "Vampire attacks: Draining life from wireless ad-hoc networks," 2009.

Other

Nicholas J. Hopper. "Toward a Theory of Steganography," CMU Ph.D. Thesis, 2004.

Nicholas J. Hopper and Manuel Blum, "A Secure Human-Computer Authentication Scheme", CMU Technical Report CMU-CS-00-139, May 2000.

Teaching

At Minnesota:
Spring 2009 - CSci 4011: Inherent Limitations of Computer Programs.
Fall 2008 - CSci 5271: Introduction to Computer Security.
Spring 2008 - CSci 5403: Complexity Theory.
Fall 2007 - CSci 5271: Introduction to Computer Security.
Spring 2007 - CSci 4011: Formal Languages and Automata Theory.
Fall 2006 - CSci 5271: Introduction to Computer Security.
Spring 2006 - CSci 4011: Formal Languages and Automata Theory.
Fall 2005 - CSci 5271: Introduction to Computer Security.
Spring 2005 - CSci 8980: Advanced Cryptography.

At CMU:
Spring 2003 - 15-859I Theoretical Aspects of Cryptography
Fall 2001 - 15-827 Security and Cryptography
Fall 2000 - 15-451 Algorithms

Etc.

The views and opinions expressed in this page are strictly those of the page author.
The contents of this page have not been reviewed or approved by the University of Minnesota.