Last Updated: July 2020

Welcome Robert Sison

Robert Sison

I am pleased to announce that Robert Sison, who just submitted his PhD thesis at UNSW, has joined as a postdoc, to work on the Time Protection project, a collaboration with Data61 and UNSW to prove that the seL4 kernel can defend against timing channels. Rob brings with him a wealth of experience in verified information flow security. During his PhD he developed the COVERN Compiler, which was the first verified compiler proved to preserve information flow security for concurrent programs, besides other achievements.

VERONICA: Open Source Release and Paper at CSF 2020

Many secure systems intentionally leak information. Proving them secure therefore means proving that they leak only the information they should leak, and only at the right times. Proving so-called secure declassification policies is a known challenging task and until very recently we have had no satisfactory methods for doing so for concurrent programs. I am therefore pleased to announce, in collaboration with Andrei Sabelfeld and Daniel Schoepe of Chalmers University of Technology, the open source release of VERONICA, which embodies a new formal approach for proving such policies for concurrent programs. VERONICA achieves a radical increase in precision and expressiveness over previous approaches, by utilising a new technique we developed called Decoupled Functional Correctness and is implemented and proved sound from first principles in the Isabelle theorem prover.

You can learn more about VERONICA in our paperpdf recently published at the 2020 IEEE Computer Security Foundations Symposium (CSF).

This work is part of the ongoing COVERN project that I lead, which focuses on methods for proving the security of concurrent programs.

Legion partakes in Test-Comp 2020

My excellent PhD student Dongge Liu has been developing a new tool Legion, for automatically generating test cases for programs, that generalises traditional concolic testing and fuzzing. Legion orchestrates program exploration via Monte-Carlo Tree Search. Legion recently took place in the 2nd Competition on Software Testing (Test-Comp 2020), which is a fantastic achievement for Dongge and his efforts over the past year of his PhD. Further details about Legion are forthcoming in a future paper. However, in the meantime you can get a sneak peek by reading our competition contribution short paper, which appeared at FASE 2020.

Welcome Mukesh Tiwari

I'm very pleased to announce that Mukesh Tiwari has joined us as a postdoc, to continue our work on Security Concurrent Separation Logic (SecCSL)pdf, for formally reasoning about information flow for concurrent programs. Mukesh joins us after a PhD at ANU, where he researched how to apply formal methods to make electronic voting more secure.

Mukesh Tiwari

About Me

I am a Senior Lecturer in the School of Computing and Information Systems of the University of Melbourne. Prior to joining Melbourne in May 2016, I was employed in the Software Systems Research Group of NICTA (now Data61), and was a Conjoint Senior Lecturer in the school of Computer Science and Engineering of UNSW. I joined NICTA and UNSW in 2010 from Oxford, where I completed a D.Phil. (PhD) in Computer Science, awarded in 2011. Before moving to Oxford, I worked for the Defence Science and Technology Organisation after my undergraduate study at the University of Adelaide.

I live in Melbourne with my wife and two children, enjoy (and sometimes write and record) alternative music, and spend too much time on Twitter engaging a hot-cold obsession with Australian politics, security and privacy. I love great ales, informed by my days in Oxford, and rich reds, like any Adelaide native.

Research and Collaborations

Note: the following is a historical snapshot of my research. See the News Archive page for a more up-to-date picture.

My research is focused on the problem of how to build highly secure computing systems cost-effectively. As part of this, I lead Data61's work on proving computer software and systems secure, and am leading or otherwise involved in a number of projects as part of Data61's Trustworthy Systems activity, as detailed on my Data61 page. Below are listed my current active areas of research and collaboration. My interest in security, and belief about the best ways to build secure systems more effectively, is very broad. Thus I tend to collaborate across various disciplines including Software Engineering, Systems, Hardware Security, Formal Methods, Programming Languages and Human Factors.

Information Flow   One of the biggest challenges faced in security today is how to ensure that computer systems can keep their secrets from well-motivated adversaries — just think of how many news stories you've read about personal information having been stolen and publicised by attackers. For this reason, a large part of my research has investigated how to guarantee the absence of unwanted information leaks in computer software and systems. I led the team that completed the world's first proof [IEEE Symposium on Security and Privacy ("Oakland" S&P) 2013 pdf] of information flow security for a general-purpose operating system kernel, seL4, which you can read more about on the Information Flow project page. This proof, along with subsequent work, guarantees that seL4 will prevent all unwanted information leaks up to timing channels, i.e. that it is free of unwanted storage channels.

My current work in this space aims to understand how to verify information flow security for concurrent programs (like those that run on top of seL4), and how to compile such programs while making sure they still preserve their security guarantees. This work is being carried out under the banner of the open-source COVERN project [IEEE European Symposium on Security and Privacy (EuroS&P) 2018 ], which builds on our earlier work for exploring these questions [IEEE Computer Security Foundations Symposium (CSF) 2016 ].

Alongisde this work, I've also been exploring how to build program logics for proving information flow security of low-level C code. A recent short paper [Workshop on Programming Languages and Analysis for Security (PLAS) 2017 pdf] describes the main ideas, developed in collaboration with Samuel Gruetter (MIT).

Timing Channels   Timing channels leak information (whether intentionally or not) to an adversary who can observe differences in the relative timing of different events. Unlike for storage channels, we are not yet able to prove the absence of timing channels in systems, largely because many timing channels exploit the timing properties of hardware microarchitectural features, like caches, which are not even documented, so are very difficult to reason about formally. For this reason, these channels must be dealt with empirically. I have been involved in NICTA's Timing and Side Channels activity, where we pioneered new techniques for empirically measuring the effectiveness of various timing channel mitigation techniques for seL4 [ACM Conference on Computer and Communications Security (CCS) 2014 pdf].

Cost-Effective Verified Systems via Verifying DSLs   While security proofs, like those for seL4 that I have led, can give extremely high levels of assurance for security-critical systems, they remain relatively expensive to perform. Much of my recent research has therefore focused on how to reduce the cost of verifying properties of systems software. One technique I have explored, in collaboration with Programming Languages researchers from UNSW (notably Gabi Keller) via NICTA's Cogent project, has been to write verified systems software in a Domain Specific Language (DSL). Cogent [International Conference on Functional Programming (ICFP) 2016 pdf] is a programming language that is carefully designed to enable systems written in it to be cheaply proved correct. It is coupled with a verifying compiler [International Conference on Interactive Theorem Proving (ITP) 2016 pdf] that automatically proves that the compiled code implements the Cogent source semantics. In conjunction with my PhD students Sidney Amani and Liam O'Connor (co-supervised with Gabi Keller), my undergraduate thesis student Japheth Lim, and the rest of the Cogent team, we have used this technique to build and (partially) formally verify correct Linux file systems far more cheaply than e.g. the verification for the seL4 kernel [International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS) 2016 html].

Proof Cost Estimation   The effort required to verify software as being secure is an obvious barrier to its wide adoption. But just as important is the inability of software engineering managers to be able to predict the costs (and associated benefits) of proving their software correct. Another of my recent research activities has been to investigate this question in the context of NICTA's Proof, Measurement and Estimation (PME) project. As part of this work, my PhD student Daniel Matichuk and I, in collaboration with Empirical Software Engineering researchers and NICTA's PME team, explored the relationship between the size of a statement to be proved about a piece of software, and the amount of effort required to prove the statement (using as a proxy the number of lines required to write the proof, which we had already established [ACM/IEEE Symposium on Empirical Software Engineering and Measurement (ESEM) 2014 pdf] is strongly linearly related). To do so, we crunched historical data about the various seL4 proofs as well as some other large, publicly available software proofs. We established empirically for the first time [International Conference on Software Engineering (ICSE) 2015 pdf] that a consistent relationship exists here and that it is in fact quadratic. This work is the first step towards building a predictive model for estimating the level of effort required to verify a piece of software.

Proof Automation   Besides writing verified software in custom DSLs leveraging verifying compilation to dramatically ease the cost of formally verifying secure systems, another more direct approach I have investigated with my PhD student Daniel Matichuk has been to develop languages in which custom, automatic proof tactics can be written for the Isabelle proof assistant. Daniel designed and developed Eisbach [International Conference on Interactive Theorem Proving (ITP) 2014 pdf, Journal of Automated Reasoning (to appear)] the first such language that integrates with Isabelle's high-level notation for writing (structured) proofs, and so requires no knowledge of Isabelle's internals, making it usable by relative novices.

Highly-Secure and Usable, Verified Cross Domain Systems   All of the above research is aimed towards being able to build extremely secure systems — and to demonstrate via rigorous evidence that they are indeed so — at reasonable cost. I am currently leading, alongside Kevin Elphinstone, a collaboration with the Defence Science and Technology Group (DST Group), in which we are building and formally verifying as secure a clever Cross-Domain device called the Cross Domain Desktop Compositor (CDDC) [Annual Computer Security Applications Conference (ACSAC) 2016 pdf]. The CDDC allows users to interact with both highly-classified and lower-classification networks from a single display (monitor), keyboard and mouse. Its design makes it far more secure than existing solutions while also offering much greater usability, showing that with clever design usability and security need not be in conflict. We are currently working on building and verifying an seL4-based implementation of the device, leveraging our current work on verified information flow security.

Usable Security   As part of my work on building and verifying cross domain systems, I am also investigating how issues of usability and security, including human cognition and perception, interact with the process of formally proving a system secure. This work is still in its very early stages [Australian Computer Human Interaction Conference (OzCHI) 2018 pdf], and there remains much more to be done.

Reasoning about Capability-Based Software   Continuing the work I began during my D.Phil. (PhD), where I investigated [thesis pdf] techniques to formally reason about the security of capability-based security-enforcing software abstractions, I am currently collaborating with researchers from Imperial College London, Victoria University Wellington and Google on techniques for formally reasoning about risk and trust (including the absence of such) for capability-based software.

My Group


Current postdocs:

Previous postdocs:

Research Students

Current PhD students:

Previous research students:

Working with Me

I'm always looking for motivated students to work with. Check out my page for prospective research students.


Google Scholar has a fairly complete list of my publications. You can also try my entry on DBLP, which may not be quite so complete.

Software and Artifacts

My group has developed various pieces of software, plus formal artifacts embedded in interactive theorem provers such as program logics and compilers. All are available under open source licenses.


SecC: Verified Security for Concurrent C Programs

SecC is the first autoactive program verifier able to verify information flow security for concurrent C programs.

More Information ->

Legion: Principled Automatic Test Case Generation

Legion automatically generates test cases for programs, generalising traditional concolic testing and fuzzing, orchestrating program exploration via Monte-Carlo Tree Search.

More Information ->


VERONICA: Verified Secure Declassification for Concurrent Programs

VERONICA is a verification method, embedded in the Isabelle/HOL theorem prover, for verifying secure declassification policies for concurrent programs.

More Information ->

COVERN Compiler: Verified Secure Compilation for Concurrent Programs

The COVERN Compiler is a proof-of-concept compiler embedded in the Isabelle/HOL theorem prover that provably preserves information flow security when compiling concurrent programs.

More Information ->

COVERN Logic: Verified Security for Concurrent Programs

The COVERN logic, embedded in the Isabelle/HOL theorem prover, allows one to prove that concurrent programs do not leak sensitive information.

More Information ->


In 2020, I am teaching:

At UNSW, I taught:

I have also taught half-day courses to industry on topics including:

If your company develops software and would like to know how you can more easily detect and remove bugs during development, and would like to know more, please get in touch.


I am the coordinator for the Master of IT Cyber Security degree specialisation and am a Research Integrity Advisor.

I serve, and have served, on a range of Program Committees, listed below. I am a member of IFIP WG 1.7 on Theoretical Foundations of Security Analysis and Design.

Steering Committees

Edited Books

Program Committees