Can Games Fix What’s Wrong with Computer Security Education?

We had the pleasure of Zachary Peterson visiting UCL on a Cyber Security Fulbright Scholarship. The title is from his presentation given at our annual ACE-CSR event in November 2016.

Zachary Peterson is an associate professor of computer science at Cal Poly, San Luis Obispo. The key problem he is trying to solve is that the educational system is producing many fewer computer security professionals than are needed; an article he’d seen just two days before the ACE meeting noted a 73% rise in job vacancies in the last year despite a salary premium of 9% over other IT jobs. This information is backed up by the 2014 Taulbee survey, which found that the number of computer security PhDs has declined to 4% of the US total. Lack of diversity, which sees security dominated by white and Asian males, is a key contributing factor. Peterson believes that diversity is not only important as a matter of fairness, but essential because white males are increasingly a demographic minority in the US and because monocultures create perceptual blindness. New perspectives are especially needed in computer security as present approaches are not solving the problem on their own.

Peterson believes that the numbers are so bad because security is under-represented in both the computer science curriculum and in curriculum standards. The ACM 2013 curriculum guidelines recommend only three contact hours (also known as credit hours) in computer security in an entire undergraduate computer science degree. These are typically relegated to an upper-level elective class, and subject to a long chain of prerequisites, so they are only ever seen by a self-selected group who have survived years of attrition – which disproportionately affects women. The result is to create a limited number of specialists, unnecessarily constrain the student body, and limit the time students have to practice before joining the workforce. In addition, the self-selected group who do study security late in their academic careers have developed both set habits and their mind set before encountering an engineering task. Changing security into a core competency and teaching it as early as secondary school is essential but has challenges: security can be hard, and pushing it to the forefront may worsen existing problems seen in computer science more broadly, such as the solitary, anti-social, creativity-deficient image perception of the discipline.

Peterson believes games can help improve this situation. CTFTime, which tracks games events, reports a recent explosion in cyber security games to over 56 games events per year since 2013. These games, if done correctly, can teach core security skills in an entertaining – and social – way, with an element of competition. Strategic thinking, understanding an adversary’s motivation, rule interpretation, and rule-breaking are essential for both game-playing and security engineering.

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Diversity is our strength

On Friday evening, US President Donald Trump signed an executive order suspending visas to citizens of seven countries for at least 90 days. Among the many other implications of this ban — none of which we want to minimise with our focus on the implications for academics — this now implies that (1) students who are citizens (even dual citizens) of these countries are now unable to study in the US or attend conferences there, and (2) academics who are citizens of these countries and who legally work and live in the US are now unable to leave (to, say, attend conferences or visit another academic institution), as they would not be allowed back in.

We receive many inquiries each year from strong applicants from these seven countries, and according to a statement issued by many US-based academics, more than 3,000 Iranian students received PhDs from American universities in the past 3 years. Across our nine faculty members, we currently have funding available for numerous PhD students and postdoctoral researchers. If any student is stranded outside of the US, we of course hope that they are able to make it back quickly, but have funding for internships that would allow them to work from here in the interim. In organising conferences, we and our wider UCL colleagues are doing all we can to organise them in places without such bans in place, and where that is not possible to enable remote participation.

Most of all, as a group that prides itself on the quality and openness of its research and on its international reach, we would like to re-affirm our commitment to working with the best possible students and academics, regardless of their religion or their country of origin (or indeed anything aside from their scientific contributions). To quote a statement from the International Association of Cryptologic Research (IACR), “the open exchange of ideas requires freedom of movement.” To address the full effects of this ban we of course need far more international cooperation, but we hope that even our small actions can help mitigate the damage that has already been done to our friends and colleagues, both within and outside of the US, and that promises to continue to be done in the future.

Nicolas Courtois
Emiliano de Cristofaro
George Danezis
Jens Groth
Sarah Meiklejohn
Steven Murdoch
David Pym
Angela Sasse
Gianluca Stringhini

Steven Murdoch – Privacy and Financial Security

Probably not too many academic researchers can say this: some of Steven Murdoch’s research leads have arrived in unmarked envelopes. Murdoch, who has moved to UCL from the University of Cambridge, works primarily in the areas of privacy and financial security, including a rare specialty you might call “crypto for the masses”. It’s the financial security aspect that produces the plain, brown envelopes and also what may be his most satisfying work, “Trying to help individuals when they’re having trouble with huge organisations”.

Murdoch’s work has a twist: “Usability is a security requirement,” he says. As a result, besides writing research papers and appearing as an expert witness, his past includes a successful start-up. Cronto, which developed a usable authentication device, was acquired by VASCO, a market leader in authentication and is now used by banks such as Commerzbank and Rabobank.

Developing the Cronto product was, he says, an iterative process that relied on real-world testing: “In research into privacy, if you build unusable system two things will go wrong,” he says. “One, people won’t use it, so there’s a smaller crowd to hide in.” This issue affects anonymising technologies such as Mixmaster and Mixminion. “In theory they have better security than Tor but no one is using them.” And two, he says, “People make mistakes.” A non-expert user of PGP, for example, can’t always accurately identify which parts of the message are signed and which aren’t.

The start-up experience taught Murdoch how difficult it is to get an idea from research prototype to product, not least because what works in a small case study may not when deployed at scale. “Selling privacy remains difficult,” he says, noting that Cronto had an easier time than some of its forerunners since the business model called for sales to large institutions. The biggest challenge, he says, was not consumer acceptance but making a convincing case that the predicted threats would materialise and that a small company could deliver an acceptable solution.

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Workshop: Theory and Practice of Secure Multiparty Computation

Members of the UCL information security group visiting Aarhus rainbow panorama.
Members of the UCL information security group visiting the Aarhus rainbow panorama

The workshop was organized by CFEM and CTIC, and took place in Aarhus from May 30 until June 3, 2016. The speakers presented both theoretical advancements and practical implementations (e.g., voting, auction systems) of MPC, as well as open problems and future directions.

The first day started with Ivan Damgård presenting TinyTable, a new simple 2-party secure computation protocol. Then Martin Hirt introduced the open problem of general adversary characterization and efficient protocol generation. The last two talks of the day discussed Efficient Constant-Round Multiparty Computation and Privacy-Preserving Outsourcing by Distributed Verifiable Computation.

The first session of the second day included two presentations on theoretical results which introduced a series of three-round secure two-party protocols and their security guarantees, and fast circuit garbling under weak assumptions. On the practical side, Rafael Pass presented formal analysis of the block-chain, and abhi shelat outlined how MPC can enable secure matchings. After the lunch break, probabilistic termination of MPC protocols and low-effort VSS protocols were discussed.

Yuval Ishai and Elette Boyle kicked off the third day by presenting constructions of function secret sharing schemes, and recent developments in the area. After the lunch break, a new hardware design enabling Verifiable ASICs was introduced and the latest progress on “oblivious memories” were discussed.

The fourth day featured presentations on RAMs, Garbled Circuits and a discussion on the computational overhead of MPC under specific adversarial models. Additionally, there was a number of presentations on practical problems, potential solutions and deployed systems. For instance, Aaron Johnson presented a system for private measurements on Tor, and Cybernetica representatives demonstrated Sharemind and their APIs. The rump session of the workshop took place in the evening, where various speakers were given at most 7 minutes to present new problems or their latest research discoveries.

On the final day, Christina Brzuska outlined the connections between different types of obfuscation and one-way functions, and explained why some obfuscators were impossible to construct. Michael Zohner spoke about OT extensions, and how they could be used to improve 2-party computation in conjunction with look-up tables. Claudio Orlandi closed the workshop with his talk on Amortised Garbled Circuits, which explained garbling tricks all the way from Yao’s original work up to the state of the art, and provided a fascinating end to the week.

Come work with us!

I’m very pleased to announce that — along with George Danezis and Tomaso Aste, head of our Financial Computing group — I’ve been awarded a grant to continue our work on distributed ledgers (aka “blockchain-like things”) for the next three years.

Our group has already done a lot of research in this space, including George’s and my recent paper on centrally banked cryptocurrencies (at NDSS 2016) and Jens’ paper (along with Markulf Kohlweiss, a frequent UCL collaborator) on efficient ring signatures and applications to Zerocoin-style cryptocurrencies (at Eurocrypt 2015).  It’s great to have this opportunity to further investigate the challenges in this space and develop our vision for the future of these technologies, so big thanks to the EPSRC!

Anyway, the point of this post is to advertise, as part of this grant, three positions for postdoctoral researchers.  We are also seeking collaboration with any industrial partners investigating the potential usage of distributed ledgers, and in particular ones looking at the application of these ledgers across the following settings (or with a whole new setting in mind!):

  • Identity management. How can identities be stored, shared, and issued in a way that preserves privacy, prevents theft and fraud, and allows for informal forms of identity in places where no formal ones exist?
  • Supply chain transparency. How can supply chain information be stored in a way that proves integrity, preserves the privacy of individual actors, and can be presented to the end customer in a productive way?
  • Financial settlement. How can banking information be stored in a way that allows banks to easily perform gross settlement, reduces the burden on a central bank, and enables auditability of the proper functioning of the system?
  • Administration of benefits. How can benefits be administered to and used by disadvantaged populations in a way that preserves privacy, provides useful visibility into their spending, and protects against potential abuses of the system?

We expect the postdoctoral researchers to work with us and with each other on the many exciting problems in this space, which are spread across cryptography, computer and network security, behavioural economics, distributed systems, usable security, human-computer interaction, and software engineering (just to name a few!).  I encourage anyone interested to reach out to me (Sarah) to discuss this further, whether or not they’ve already done research on the particular topic of distributed ledgers.

That’s all for now, but please get in touch with me if you have any questions, and in the years to come I hope to invite many people to come work with us in London and to announce the various outcomes of this exciting project!

Jens Groth – Non-interactive zero knowledge proofs, efficient enough to be used in practice

The UCL information security group’s Jens Groth, a cryptographer, is one of 17 UCL researchers who have been awarded a Starting Grant by the European Research Council. The five-year grant will fund his work on the cryptographic building block known as “zero-knowledge proofs”, a widely applicable technique that underpins both security and trust. ERC Starting Grants are intended to support up-and-coming research leaders who are beginning to set up a research team and conduct independent research. Groth’s focus is on making zero- knowledge proofs more efficient so that they can become cheap enough to become a commonly used, standard security technology. Groth is also the recipient of a second grant from the Engineering and Physical Sciences Research Council to fund his work on another related topic, structure-preserving pairing-based cryptography.

“My line of thinking,” says Groth, “is that there’s been a lot of research into zero-knowledge proofs, but I don’t know of any groups taking entire systems from theory through to very practical implementations. I am hoping to build a group that will cover this entire span, and by covering it thoroughly get some very significant gains in efficiency.” Covering that entire spectrum from the purely abstract to the built system is important, he says, because “Practice can influence theory and give us some insight into what we should be looking at. Also, when you start implementing things, lots of surprising discoveries can come up.”

Unlike other types of cryptographic tools, such as public key cryptography, used in such widely used mass-market applications as SSL (used to secure data passed over the Web while in transit), Groth notes that zero-knowledge proofs are more likely to be a behind-the-scenes technology that end users will never touch directly.

“It will be hidden inside the system,” he says. “The main properties we want are completeness, soundness – and zero-knowledge.” Completeness means the prover can convince the verifier when a statement is true. Soundness means the prover cannot convince the verifier when the statement is false. Finally, zero-knowledge means that there is no leakage of information even if the prover is interacting with a fraudulent verifier.

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ACE-CSR opening event 2015/16: talks on malware, location privacy and wiretap law

The opening event for the UCL Academic Centre of Excellence for Cyber Security Research in the 2015–2016 academic term featured three speakers: Earl Barr, whose work on approximating program equivalence has won several ACM distinguished paper awards; Mirco Musolesi from the Department of Geography, whose background includes a degree in computer science and an interest in analysing myriad types of data while protecting privacy; and Susan Landau, a professor at Worcester Polytechnic Institute and a visiting professor at UCL and an expert on cyber security policy whose books include Privacy On the Line: the Politics of Wiretapping and Encryption (with Whitfield Diffie) and Surveillance or Security? The Risks Posed by New Wiretapping Technologies.

Detecting malware and IP theft through program similarity

Earl Barr is a member of the software systems engineering group and the Centre for Research on Evolution, Search, and Testing. His talk outlined his work using program similarity to determine whether two arbitrary programs have the same behaviour in two areas relevant to cyber security: malware and intellectual property theft in binaries (that is, code reused in violation of its licence).

Barr began by outlining his work on detecting malware, comparing the problem to that facing airport security personnel trying to find a terrorist among millions of passengers. The work begins with profiling: collect two zoos, and then ask if the program under consideration is more likely to belong to the benign zoo or the malware zoo.

Rather than study the structure of the binary, Barr works by viewing the program as strings of 0s and 1s, which may not coincide with the program’s instructions, and using information theory to create a measure of dissimilarity, the normalised compression distance (NCD). The NCD serves as an approximation of the Kolmogorov Complexity, a mathematical measure of the complexity of the shortest description of an object, which is then normalised using a compression algorithm that ignores the details of the instruction set architecture for which the binary is written.

Using these techniques to analyse a malware zoo collected from sources such as Virus Watch, Barr was able to achieve a 95.7% accuracy rate. He believes that although this technique isn’t suitable for contemporary desktop anti-virus software, it opens a new front in the malware detection arms race. Still, Barr is aware that malware writers will rapidly develop countermeasures and his group is already investigating counter-countermeasures.

Malware writers have three avenues for blocking detection: injecting new content that looks benign; encryption; and obfuscation. Adding new content threatens the malware’s viability: raising the NCD by 50% requires doubling the size of the malware. Encryption can be used against the malware writer: applying a language model across the program reveals a distinctive saw-toothed pattern of regions with low surprise and low entropy alternating with regions of high surprise and high entropy (that is, regions with ciphertext). Obfuscation is still under study: the group is using three obfuscation engines available for Java and applying them repeatedly to Java malware. Measuring the NCD after each application shows that after 100 iterations the NCD approaches 1 (that is, the two items being compared are dissimilar), but that two of the three engines make errors after 200 applications. Unfortunately for malware writers, this technique also causes the program to grow in size. The cost of obfuscation to malware writers may therefore be greater than that imposed upon white hats.

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Nicolas Courtois – Algebraic cryptanalysis is not the best way to break something, but sometimes it is the only option

Nicolas Courtois, a mathematician and senior lecturer in computer science at UCL, working with Daniel Hulme and Theodosis Mourouzis, has won the 2012 best paper award from the International Academy, Research, and Industry Association for their work on using SAT solvers to study various problems in algebra and circuit optimization. The research was funded by the European Commission under the FP7 project number 242497, “Resilient Infrastructure and Building Security (RIBS)” and by the UK Technology Strategy Board under project 9626-58525. The paper, Multiplicative Complexity and Solving Generalized Brent Equations with SAT Solvers, was presented at Computation Tools 2012, the third International Conference on Computational Logics, Algebras, Programming, Tools, and Benchmarking, held in Nice, France in July.

SAT (short for “satisfiability”) solvers are algorithms used to analyse logical problems composed of multiple statements such as “A is true OR not-B is true or C is true” for the purpose of determining whether the whole system can be true – that is, whether all the statements it’s composed of can be satisfied. SAT solvers also are used to determine how to assign the variables to make the set of statements true. In 2007, Bard and Courtois realised they could be used to test the security of cryptographic functions and measure their complexity, and today they are important tools in cryptanalysis; they have already been used for a long time in other applications such as verifying hardware and software. In this particular paper, Courtois, Hulme, and Mourouzis focused on optimising S-boxes for industrial block ciphers; the paper reports the results of applying their methodology to the PRESENT and GOST block ciphers. Reducing the complexity and hardware cost of these ciphers is particularly important to build so-called secure implementations of cryptography. These are particularly costly because they need to protect against additional threats such as side-channel attacks, in which the attacker exploits additional information leaked from the physical system – for example, by using an oscilloscope to observe a smart card’s  behaviour.

“It’s more a discovery than an invention,” says Courtois. “One of the amazing things SAT solvers can do is give you proof that something is not true.” The semiconductor industry provides one application of the work in this paper: these techniques promise to provide a way to test whether a circuit has been built with the greatest possible efficiency by proving that the chip design uses the smallest possible number of logic gates.

“You’ll get optimal designs and be able to prove they cannot be done better,” he says.

Classical cryptanalysis proceeds by finding approximations to the way a cipher works. Many successful academic attacks have been mounted using such techniques, but they rely on having a relatively large amount of data available for study. That works for large archives of stored data – such as, for example, the communications stored and kept by the Allies after World War II for later cryptanalysis. But in many real-world applications, it is more common to have only very small amounts of data.

“The more realistic scenario is that you’ll just have one or a few messages,” says Courtois. Bluetooth, for example, encrypts only 1,500 bits with a single key. “Most attacks are useless because they won’t work with this quantity of data.” Algebraic cryptanalysis, which he explained in New Frontier in Symmetric Cryptanalysis, an invited talk at Indocrypt 2008, by contrast, is one of the few techniques that can be hoped to work in such difficult situations.

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Sarah Meiklejohn – Security and Cryptography

Sarah Meiklejohn As a child, Sarah Meiklejohn thought she might become a linguist, largely because she was so strongly interested in the work being done to decode the ancient Greek writing systems Linear A and Linear B.

“I loved all that stuff,” she says. “And then I started doing mathematics.” At that point, with the help of Simon Singh’s The Code Book, she realised the attraction was codebreaking rather than human languages themselves. Simultaneously, security and privacy were increasingly in the spotlight.

“I’m a very private person, and so privacy is near and dear to my heart,” she says. “It’s an important right that a lot of people don’t seem interested in exercising, but it’s still a right. Even if no one voted we would still agree that it was important for people to be able to vote.”

It was during her undergraduate years at Brown, which included a fifth-year Masters degree, that she made the transition from mathematics to cryptography and began studying computer science. She went on to do her PhD at the University of California at San Diego. Her appointment at UCL, which is shared between the Department of Computer Science and the Department of Crime Science, is her first job.

Probably her best-known work is A Fistful of Bitcoins: Characterizing Payments Among Men with No Names (PDF), written with Marjori Pomarole, Grant Jordan, Kirill Levchenko, Damon McCoy, Geoffrey M. Voelker, and Stefan Savage and presented at USENIX 2013, which studied the question of how much anonymity bitcoin really provides.

“The main thing I was trying to focus on in that paper is what bitcoin is used for,” she says. The work began with buying some bitcoin (in 2012, at about £3 each), and performing some transactions with them over a period of months. Using the data collected this way allowed her to uncover some “ground truth” data.

“We developed these clustering techniques to get down to single users and owners.” The result was that they could identify which addresses belonged to which exchanges and enabled them to get a view of what was going on in the network. “So we could say this many bitcoins passed through this exchange per month, or how many were going to underground services like Silk Road.”

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George Danezis – Smart grid privacy, peer-to-peer and social network security

“I work on technical aspects of privacy,” says George Danezis, a reader in security and privacy engineering at UCL and part of the Academic Centre of Excellence in Cyber Security Research (ACE-CSR). There are, of course, many other limitations: regulatory, policy, economic. But, he says, “Technology is the enabler for everything else – though you need everything else for it to be useful.” Danezis believes providing privacy at the technology level is particularly important as it seems clear that both regulation and the “moralising” approach (telling people the things they shouldn’t do) have failed.

There are many reasons why someone gets interested in researching technical solutions to intractable problems. Sometimes the motivation is to eliminate a personal frustration; other times it’s simply a fascination with the technology itself. For Danezis, it began with other people.

“I discovered that a lot of the people around me could not use technology out of the box to do things personally or collectively.” For example, he saw NGOs defending human rights worry about sending an email or chatting online, particularly in countries hostile to their work. A second motivation had to do with timing: when he began work it wasn’t yet clear that the Internet would develop into a medium anyone could use freely to publish stories. That particular fear has abated, but other issues such as the need for anonymous communications and private data sharing are still with us.

“Without anonymity we can’t offer strong privacy,” he says.

Unlike many researchers, Danezis did not really grow up with computers. He spent his childhood in Greece and Belgium, and until he got Internet access at 16, “I had access only to the programming books I could find in an average Belgian bookshop. There wasn’t a BBC Micro in every school and it was difficult to find information. I had one teacher who taught me how to program in Logo, and no way of finding more information easily.” Then he arrived at Cambridge in 1997, and “discovered thousands of people who knew how to do crazy stuff with computers.”

Danezis’ key research question is, “What functionality can we achieve while still attaining a degree of hard privacy?” And the corollary: at what cost in complexity of engineering? “We can’t just say, let’s recreate the whole computer environment,” he said. “We need to evolve efficiently out of today’s situation.”

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