Dr Steven J. Murdoch

I am a Royal Society University Research Fellow in the Information Security Research Group of the Department of Computer Science at University College London. I am also a bye-fellow of Christ’s College, Security Architect at the VASCO Innovation Center, Cambridge, and a member of the Tor Project.

Open positions

I am always interested in recruiting talented researchers to join my team at UCL, both as PhD students and for post-doctoral positions. Interested candidates should email me their curriculum vitae and a short research proposal.

Tweets for @sjmurdoch

Dr Steven J. Murdoch

Recent publications

For more details see my full list of publications or my Google Scholar page. I also write articles on information security for the UCL Information Security Group blog – Bentham’s Gaze, and my occasional non-security articles are published on my personal blog.

  • Fast Protection-Domain Crossing in the CHERI Capability-System Architecture
    Robert N.M. Watson, Robert Norton, Jonathan Woodruff, Simon W. Moore, Peter G. Neumann, Jonathan Anderson, David Chisnall, Brooks Davis, Michael Roe, Nirav Dave, Khilan Gudka, Alexandre Joannou, A. Theodore Markettos, Ed Maste, Steven J. Murdoch, Colin Rothwell, Stacey Son, Munraj Vadera
    Capability Hardware Enhanced RISC Instructions (CHERI) supplement the conventional memory management unit (MMU) with instruction-set architecture (ISA) extensions that implement a capability system model in the address space. CHERI can also underpin a hardware-software object-capability model for scalable application compartmentalization that can mitigate broader classes of attack. This article describes ISA additions to CHERI that support fast protection-domain switching, not only in terms of low cycle count, but also efficient memory sharing with mutual distrust. The authors propose ISA support for sealed capabilities, hardware-assisted checking during protection-domain switching, a lightweight capability flow-control model, and fast register clearing, while retaining the flexibility of a software-defined protection-domain transition model. They validate this approach through a full-system experimental design, including ISA extensions, a field-programmable gate array prototype (implemented in Bluespec SystemVerilog), and a software stack including an OS (based on FreeBSD), compiler (based on LLVM), software compartmentalization model, and open-source applications.
    IEEE Micro, Volume 36, Issue 5, pages 38–49. IEEE, September–October 2016. [ paper | DOI 10.1109/MM.2016.84 ]
  • Adblocking and Counter-Blocking: A Slice of the Arms Race
    Rishab Nithyanand, Sheharbano Khattak, Narseo Vallina-Rodriguez, Mobin Javed, Marjan Falahrastegar, Julia E. Powles, Emiliano De Cristofaro, Hamed Haddadi, Steven J. Murdoch
    Adblocking tools like Adblock Plus continue to rise in popularity, potentially threatening the dynamics of advertising revenue streams. In response, a number of publishers have ramped up efforts to develop and deploy mechanisms for detecting and/or counter-blocking adblockers (which we refer to as anti-adblockers), effectively escalating the online advertising arms race. In this paper, we develop a scalable approach for identifying third-party services shared across multiple websites and use it to provide a first characterization of anti-adblocking across the Alexa Top-5K websites. We map websites that perform anti-adblocking as well as the entities that provide anti-adblocking scripts. We study the modus operandi of these scripts and their impact on popular adblockers. We find that at least 6.7% of websites in the Alexa Top-5K use anti-adblocking scripts, acquired from 12 distinct entities – some of which have a direct interest in nourishing the online advertising industry.
    6th USENIX Workshop on Free and Open Communications on the Internet (FOCI '16), Austin, TX, US, 08 August 2016. [ paper | slides | data ]
  • A Framework for the Game-theoretic Analysis of Censorship Resistance
    Tariq Elahi, John A. Doucette, Hadi Hosseini, Steven J. Murdoch, Ian Goldberg
    We present a game-theoretic analysis of optimal solutions for interactions between censors and censorship resistance systems (CRSs) by focusing on the data channel used by the CRS to smuggle clients’ data past the censors. This analysis leverages the inherent errors (false positives and negatives) made by the censor when trying to classify traffic as either non-circumvention traffic or as CRS traffic, as well as the underlying rate of CRS traffic. We identify Nash equilibrium solutions for several simple censorship scenarios and then extend those findings to more complex scenarios where we find that the deployment of a censorship apparatus does not qualitatively change the equilibrium solutions, but rather only affects the amount of traffic a CRS can support before being blocked. By leveraging these findings, we describe a general framework for exploring and identifying optimal strategies for the censorship circumventor, in order to maximize the amount of CRS traffic not blocked by the censor.We use this framework to analyze several scenarios with multiple data-channel protocols used as cover for the CRS. We show that it is possible to gain insights through this framework even without perfect knowledge of the censor’s (secret) values for the parameters in their utility function.
    Proceedings on Privacy Enhancing Technologies, Volume 2016, Number 4, pages 83–101. De Gruyter Open, July 2016. (Journal of the 16th Privacy Enhancing Technologies Symposium, Darmstadt, Germany). [ paper | DOI 10.1515/popets-2016-0030 ]

Recent talks

For more detail see my full list of talks

  • Payment Security: Attacks & Defences
    Steven J. Murdoch
    This lecture provides an introduction to payment card and online banking security mechanisms and the fraud techniques which are designed to break or bypass these measures. An overview of the EMV protocol is given, along with an illustration of how skimming attacks and the no-PIN attack exploit protocol weaknesses. The man-in-the-browser attack is outlined, and how transaction authentication is intended to defend against this.
    Guest lecture as part of COMPGA03 - Introduction to Cryptography, University College London, 13 December 2016. [ slides ]
  • Decentralising Data Collection and Anonymisation
    Steven J. Murdoch
    A frequent approach for anonymising datasets is for individuals to submit sensitive data records to a central authority. The central authority then is responsible for safely storing and sharing the data, for example by aggregating or perturbing records. However, this approach introduces the risk that the central authority may be compromised, whether this from an externally originated hacking attempt or as a result of an insider attack. As a result, central authorities responsible for handling sensitive data records must be well protected, often at great expense, and even then the risk of compromise will not be eliminated. In this talk I will discuss an alternative anonymisation approach, where sensitive data records have identifiable information removed before being submitted to the central authority. In order for this approach to work, not only must this first-stage anonymisation prevent the data from disclosing the identity of the submitter, but also the data records must be submitted in such a way as to prevent the central authority from being able to establish the identity of the submitter from submission metadata. I will show how advances in network metadata anonymisation can be applied to facilitate this approach, including techniques to preserve validity of data despite not knowing the identity of contributors.
    New Developments in Data Privacy, Isaac Newton Institute, 09 December 2016. [ slides | video ]
  • Anonymity & Censorship-Free Communication
    Steven J. Murdoch
    This talk discusses the history of anonymous communication systems, their applications (including censorship resistance), how they are designed, and what cryptographic mechanisms they use. Techniques to measure and quantify the security levels provided by anonymous communication systems are also covered. Finally, challenges faced by such systems are discussed, along with future directions for research.
    Invited talk at IFIP Summer School 2016, Karlstad, Sweden, 21–26 August 2016. [ slides | slides (PDF) ]

Professional activities

Research supervision

Andreas Gutmann (PhD student, 2016–): privacy-preserving transaction authentication for mobile devices.

Sheharbano Khattak (Research Assistant & PhD student, 2013–): measurement of censorship and censorship resistance systems.

Kumar Sharad (PhD student, 2012–2016): security in social networks – anonymisation and fraud prevention.

Program chair

14th Privacy Enhancing Technologies Symposium, 16–18 July, 2014, Amsterdam, Netherlands.

15th Privacy Enhancing Technologies Symposium, 30 June–2 July 2015, Philadelphia, PA, USA.

General chair

Financial Cryptography and Data Security 2011, 15th International Conference, 28 February–4 March 2011, St. Lucia.

Programme committee membership

  • Network and Distributed System Security Symposium (NDSS): 2017
  • Privacy Enhancing Technologies Symposium (PETS): 2007, 2008, 2009, 2011, 2017
  • ACM Conference on Computer and Communications Security (CCS): 2007, 2008, 2010, 2011, 2016
  • IFIP Summer School 2016
  • Financial Cryptography and Data Security (FC): 2010, 2016
  • Annual Privacy Forum 2014
  • Free and Open Communications on the Internet (FOCI) 2013
  • USENIX Security 2012
  • European Symposium on Research in Computer Security (ESORICS) 2011
  • Workshop on Foundations of Security and Privacy (FCS-PrivMod): 2010
  • Workshop on Privacy in the Electronic Society (WPES): 2006, 2007, 2009
  • FIDIS/IFIP Internet Security & Privacy Summer School: 2008
  • ACM Symposium on Applied Computing (Computer Security track): 2007

Journal reviewing

Includes International Journal of Computer Security (2016), IEEE Transactions on Dependable and Secure Computing (2009), ACM Transactions on Information and System Security (2008), IEEE Transactions on Software Engineering (2008), IEEE/ACM Transactions on Networking (2007), IEEE Security & Privacy (2007), The Triple Helix (2008), Identity in the Information Society (2008).

Contact Details

email (preferred):

s.murdoch at ucl.ac.uk
OpenPGP public key 0x5E2A64A6 (more details)


Dr Steven J. Murdoch
Computer Science Department
University College London
Gower Street
United Kingdom


+44 20 3108 1629 (internal x51629)


+44 7866 807 628