The first paper (public preprint) summarises some of the key contributions of Robert Sison's PhD thesis, on verified secure compilation
of concurrent programs while preserving information flow security.
The second paper summarises the key contributions of
the Cogent project.
Together these two papers highlight the breadth of recent work on secure
compilation. Check out the special issue to see even more.
Eureka Prize for Outstanding Science in Safeguarding Australia
I'm delighted to announce that my PhD student Pengbo Yan and I have a paper that
will be appearing at OOPSLA 2021. Our paper describes SecRSL which is a program logic we developed for proving that concurrent C programs that make use of C11's Release-Acquire weak memory features are information-flow secure. SecRSL is the first information flow logic
developed for a high-level language able to reason about weak-memory concurrency. Moreover it is the first security separation logic proved sound over an axiomatic memory model, and so our paper also presents the first formal definition
of information flow security for an axiomatic memory model. We describe not only SecRSL but also how we applied it to verify a range of secure concurrency primitives and how, by taking advantage of C11's weak-memory concurrency features, those primitives perform much better than their traditional sequentially-consistent counterparts. We hope SecRSL will herald many more secure concurrent programs in future.
SecRSL is the latest success from my ongoing COVERN project.
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 ]
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.
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 ].
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 ] 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 ] 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 ].
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 ]
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 ] 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 , 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 ].
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.
Reasoning about Capability-Based Software
Continuing the work I began during my D.Phil. (PhD), where I investigated
[thesis ] 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.
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.
A
general-purpose logic that enables one to perform under-approximate reasoning about relational
properties, and the fist logic able to prove when programs are insecure.
SecRSL: How to Prove Efficient, Concurrent Programs Secure
The first security separation program logic able to reason about C11's weak
memory concurrency features used by highly-efficient concurrent C programs.
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.
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.
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.
