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Maxwell's fluid model of magnetism
shows that a wavepacket travelling along a phase vortex in an Eulerian fluid
obeys Maxwell's equations, is emitted and absorbed discretely, and can have
linear or circular polarisation. What's more, the measured correlation between
the polarisation of two cogenerated wavepackets is exactly the same as predicted
by quantum mechanics, and observed in the Bell tests (blog).
collection, linking and use of data in biomedical research and health care:
ethical issues is a report we wrote for the Nuffield Bioethics Foundation:
wha happens to health privacy in a world with cloud-based medical records and
pervasive genomics? (blog Guardian Indy Press Association Science)
freeze or not to freeze shows how you may be able to build a better lie
detector by analysing body motion (Blog post Guardian Mail). A companion paper, Mining
Bodily Cues to Deception, analyses the signals that can be extracted
from different limb movements. Both papers appeared at HICSS 2015.
versus government surveillance – where network effects meet public
choice examines the economics of surveillance: the Snowden papers show that
information economics applies to the NSA and GCHQ, just as it applies to Google
and Microsoft (blog Schneier)
Skim: Cloning EMV Cards with the Pre-Play Attack describes attacks based on
design and implementation flaws in EMV that are actually being exploited in
Spain, Poland and elsewhere (blog)
protocols and evidence: where many payment systems fail analyses why
dispute resolution is hard. In a nutshell, the systems needed to support it
properly just don't get built (blog).
In Why bouncing droplets are a pretty good
model of quantum mechanics, we solve an outstanding mystery in physics (see blog posts, three previous papers and older blog posts).
may harm your computer – The psychology of malware warnings analyses
what sort of text we should put in a warning if we actually want the user to
pay attention to it (blog).
2013 highlights included Rendezvous, a
prototype search engine for code; a demonstration that we could steal your PIN
via your phone camera
and microphone; an analysis of SDN
Authentication; and papers on quantum computing and Bell's inequality.
2012 highlights included a big report on Measuring
the Cost of Cybercrime and a history of
security economics; an attempt to kill the government's smart metering project; three
papers on dynamic
networks; and four papers on payment protocols: Chip and Skim: cloning
EMV cards with the pre-play attack, How
Certification Systems Fail, A
birthday present every eleven wallets? and Social
Authentication – harder than it looks. Finally, Risk
and privacy implications of consumer payment innovation discusses both
payment and economic issues.
2011 highlights included a major report on the Resilience
of the Internet Interconnection Ecosystem which studies how an attacker
might bring down the Internet; an updated survey paper on Economics and
Internet Security which covers recent analytical, empirical and behavioral
research; and Can We Fix the
Security Economics of Federated Authentication? which explores how we can
deal with a world in which your mobile phone contains your credit cards, your
driving license and even your car key. What happens when it gets stolen or
2010 highlights included a paper on why Chip
and PIN is broken for which we got coverage on Newsnight and a best
paper award (later, the banks tried to suppress
this research). Other bank security work included a paper on Verified by
VISA and another
on the unwisdom of banks adopting proprietary standards. On the control systems
front, we published papers on the technical
security and security
economics of smart meters, on their privacy, on their
deployment and on key management for
substations. I created a psychology and security web
page and wrote a paper on putting
context and emotion back in security decisions.
2009 highlights included Database
State, an influential report we wrote about the failings of public-sector IT
in Britain (a number of its recommendations have been adopted by the new
government); The snooping
dragon which explains how the Chinese spooks hacked the Dalai Lama in the
run-up to the Peking Olympics; Eight Friends
are Enough, which shows how little privacy you have on Facebook; and The Economics of Online
Crime. There are also videos of talks I gave on dependability at
Krakow and De
Montfort, as well as a survey paper,
and a podcast. Finally,
I wrote an Unauthorised
History of Cambridge University.
2008 highlights included
a major study of Security Economics
and European Policy for the European Commission; the second edition of my
Engineering"; the discovery
vulnerabilities in Chip and PIN payment systems;
an analysis of the failings
of the Financial Ombudsman Service (see also
a video from the World
Economic Forum in November 2008); the
FIPR submission to the
Thomas-Walport Review; a piece
in the British Journal of General Practice; three videos on
privacy made by ARCH; and a video on surveillance. I
started a Workshop
on Security and Human Behaviour to bring together psychologists with
economists and security engineers to work on deception and risk.
2007 highlights included technical papers
on RFID and
on New Strategies
for Revocation in Ad-Hoc Networks (which explores when suicide attacks are
tech talk on searching for covert communities online; a paper on fraud, risk and
nonbank payment systems I wrote for the Fed; and a survey paper on Information
Security Economics (of which a shortened version appeared in Science). I was a
special adviser to House of Commons Health Committee for their Report
on the Electronic Patient Record. Finally, following the HMRC data loss, I
appeared in the debate on Newsnight.
highlights included technical papers on topics from protecting
power-line communications to the
Man-in-the-Middle Defence, as well as a major report on the safety and privacy of
children's databases for the UK Information Commissioner, which got a lot of
publicity. I ended the year by debating
health privacy on the Today programme with health minister Lord Warner, who
resigned shortly aftewards.
highlights included research papers on The topology of
covert conflict, on combining
cryptography with biometrics, on Sybil-resistant DHT
routing, and on Robbing the bank
with a theorem prover; and a big survey paper on cryptographic
highlights included papers on cipher
establishment in ad-hoc networks and the economics of
censorship resistance. I also lobbied for amendments to the EU IP Enforcement
Directive and organised a workshop on copyright which led to a common position adopted by
many European NGOs.
I am Professor of Security Engineering at the Computer Laboratory. My research
students are Sheharbano Khattak,
Kumar Sharad, Laurent Simon, Rubin Xu and Dongting Yu. Richard Clayton, Sergei Skorobogatov, David Modic, Sophie van der
Zee and Alice
Hutchings are postdocs. I'm also collaborating
with Robert Brady. Alumni include
former postdocs Mike Bond,
Vashek Matyas, Steven Murdoch and Andrei
Serjantov, while Jong-Hyeon Lee, Frank Stajano, Fabien Petitcolas, Harry
Manifavas, Markus Kuhn,
Ulrich Lang, Jeff Yan, Susan Pancho,
Mike Bond, George Danezis, Sergei Skorobogatov, Hyun-Jin Choi, Richard Clayton, Jolyon Clulow, Hao Feng, Andy Ozment, Tyler Moore, Shishir Nagaraja, Robert Watson, Hyoungshick Kim, Shailendra Fuloria, Joe Bonneau and Wei-Ming Khoo have earned PhDs.
My research topics include:
By default, when I post a paper here I license it under the relevant Creative Commons
license, so you may redistribute it with attribution but not modify it. I
may subsequently assign the residual copyright to an academic publisher.
Economics and Psychology of information security
As systems scale globally, incentives start to matter as much as technology.
Systems break when the people who could fix them are not the people who suffer
the costs of failure. So it's not enough for security engineers to understand
cryptomathematics and the theory of operating systems; we have to understand
game theory and microeconomics too. This has led to a rapidly growing interest
in ‘security economics’, a discipline I helped to found. This
discipline is starting to embrace dependability and software economics; at the
other end, it's growing through bevaioural economics into the psychology of
security. I maintain
the Economics and
Security Resource Page and a similar web page
Psychology. There is also a web page on
of privacy, maintained by Alessandro Acquisti. My research contributions
include the following.
- Reading this
may harm your computer – The psychology of malware warnings analyses
what sort of text we should put in a warning if we actually want the user to
pay attention to it (blog).
the Cost of Cybercrime sets out to debunk the scaremongering around online
crime that governments and defence contractors are using to justify everything
from increased surveillance to preparations for cyberwar. It was written in
response to a request from the UK Ministry of Defence, and appeared at WEIS 2012 (press: BBC WSJ PC
- We wrote a major report for ENISA on the
Resilience of the Internet interconnection ecosystem which has been
adopted as ENISA policy. We believe this is the first time anyone has
documented how the Internet actually works in practice, as opposed to in theory.
The serious student will want the full
report (238 pages) while here, for the busy, is the 31-page executive
- From time to time, Tyler Moore and I write a survey paper on security
economics. Here is the latest (2011): Economics and
Internet Security: a Survey of Recent Analytical, Empirical and Behavioral
Research. Our previous survey paper, Information
Security Economics – and Beyond, appeared in various versions from
2006 to 2009. There was a short survey in
Science in late 2006; a version for
economists at Softint in January 2007; a version for
security engineers at Crypto in August 2007 (see slides); a book
chapter for mathematicians; a video
of a survey talk at De Montfort, and finally an archival journal version in Phil
Trans Roy Soc A (Aug 2009).
Economics – A Personal Perspective is an invited paper I gave at ACSAC 2012 telling the story of how security economics
got going as a subject. This is often credited to a paper I gave at ACSAC 2001
but the real story is more complex.
- It's the
Anthropology, Stupid! discusses how we might put context and emotion back
into security decisions.
- The Economics of
Online Crime appeared in the Journal of Economic Perspectives; it looks at
the econometrics of fraud and phishing, and makes a number of suggestions for
improving the responses of banks and law-enforcement agencies.
- The Impact
of Incentives on Notice and Take-down examines how take-down speed varies
with the incentive of the party requesting removal. Banks are quick to remove
phishing websites that mention them by name, but they ignore mule recruitment
websites because it's harder to tell which bank will be affected.
- We have two futher papers on security economics in banking. The first is
on Verified by
VISA – the mechanism that asks for your card password when you shop
online. This is an example of how a poor design can win out if it has strong
deployment incentives (see
post and slides).
The second, On
the Security of Internet Banking in South Korea, analyses the effects of
Korea's decision to use national cryptography standards for Internet banking
rather than just using the same protocols as the rest of the world.
- On the
security economics of electricity metering appeared at WEIS 2010 and warns
that the government's smart meter programme probably won't work. Other papers
on security economics and control systems include Security Economics
and Critical National Infrastructure (at WEIS 2009); Certification and
Evaluation (at IEEE ETFA
2009); The Protection
of Substation Communications (SCADA Security Scientific Symposium, 2010);
a security architecture for substations (IEEE PES – ISGT Europe,
- The Trust Economy
of Brief Encounters argues that as transactions become more transient, we
will have to authenticate more; it appeared at the protocols workshop in 2009.
- We did a major study of Security Economics in the Single Market for the European Network
and Information Security Agency. We looked at the market failures underlying
spam, phishing and other online problems, and made concrete policy proposals,
some of which have been adopted. A shorter
version (62 pages) appeared at WEIS 2008 (slides)
and an even
shorter version (25 pages), at ISSE.
- Closing the
Phishing Hole – Fraud, Risk and Nonbanks reports research on payment
regulation commissioned by the US Federal Reserve. This paper identified speedy
asset recovery as the best way to deter online fraud and rapid, irrevocable
payment instruments (such as Western Union) as a systemic threat.
- Why Information
Security is Hard – An Economic Perspective was the paper that got
information security people thinking about economics. It applies microeconomic
analysis to explain many phenomena that security folks had found to be
pervasive but perplexing.
- My `Trusted
Computing' FAQ undermined the Trusted Computing Group's initiative to
install DRM hardware in every computer, PDA and mobile phone. `TC' was sold to
Hollywood as a DRM platform but its real beneficiary would have been the
software industry whose customers would have been locked in more tightly. Cryptography and
Competition Policy – Issues with `Trusted Computing' is an economic
analysis I gave at WEIS2003 and as an
invited talk at PODC 2003. A short version
of the paper appeared in Upgrade
translation). I spoke about TC at the "Trusted Computing Group" Symposium, which helped
drive German and EU policy. The row was ignited by a paper on the security
of free and open source software I gave at Softint 2002; see coverage in the
New York Times and The Register.
- In my paper on the security
of free and open source software, I show that the old argument whether
source code access makes it easier for the defenders to
find and fix bugs, or easier
for the attackers to find and exploit them is misdirected. Under standard
assumptions used in reliability growth modelling, the two will exactly cancel
each other out. That means that whether open or closed systems are more secure
in a given situation will depend on whether, and how, the application deviates
from the standard assumptions. These ideas are developed further in Open and Closed
Systems are Equivalent (that is, in an ideal world) which appeared as a
chapter in Perspectives
on Free and Open Source Software. See press coverage in slashdot, news.com and The
- On Dealing with
Adversaries Fairly applies election theory (also known as social choice
theory) to the problem of shared control in distributed systems.
- The Economics
of Censorship Resistance examines when it is better for defenders to
aggregate or disperse. Should file-sharers build one huge system like gnutella
and hope for safety in numbers, or should everyone just share the stuff they
care about? More generally, what are the tradeoffs between diversity and
solidarity when conflict threatens? (This is a live topic in social policy
Goodhart's essay, a response in
and a post
Shirkey.) This paper appeared
at WEIS 2004.
- Here are papers on The Initial Costs
and Maintenance Costs of Protocols, which I gave at Security Protocols
2005, and How
Much is Location Privacy Worth? which I gave at WEIS 05.
There are two annual workshops I helped establish. On the psychology side, the
Security and Human Behaviour
workshop is great fun and hugely productive. On the economic side,
the Workshop on Economics and
Information Security is now into its thirteenth year and attracts over a
Peer-to-Peer and social network systems
Since about 2000, there has been an explosion of interest in peer-to-peer
and ad-hoc networking. One of the seminal papers was The Eternity
Service, which I presented at Pragocrypt 96. I had been alarmed by the
Scientologists' success at closing down the penet remailer
in Finland, and have more than once been threatened
by lawyers who did not want me to comment on the security of their clients'
systems. Yet the modern era only started once the printing press enabled
seditious thoughts to be spread too quickly and widely to ban. But when books no
longer exist as tens of thousands of paper copies, but as a file on a single
server, will government ministers and judges be able to unpublish them once
more? (This has
to newspaper archives in Britain.) So I invented the Eternity Service as a
means of putting electronic documents beyond the censor's grasp. The Eternity Service
inspired second-generation censorship-resistant systems such as Publius and Freenet; one descendant of these
early systems is wikileaks. Our main
contribution nowadays lies in helping to maintain Tor, the anonymity service used by
wikileaks and by many others.
But the biggest deal turned out to be not sedition, or even pornography, but
copyright. Hollywood's action against Napster led to our ideas being
adopted in filesharing systems. Many of these developments were described here,
and discussed at conferences like this one. See also
Richard Stallman's classic, The Right to Read.
Many of the ideas in early peer-to-peer systems reemerged in the study of ad-hoc
and sensor networks and are now spilling over into social networking systems.
My contributions since the Eternity paper include the following.
Experimental Evaluation of Robustness of Networks studies the best attack
and defence strategies in different kinds of networks. It builds on an earlier
topology of covert conflict which asked how the police can best target an
underground organisation given some knowledge of its patterns of communication,
and how might they in turn might react to various law-enforcement strategies.
Our framework combines ideas from network analysis and evolutionary game
theory to explore the interaction of attack and defence strategies in
Authentication – harder than it looks shows how Facebook's soocial
captcha system is vulnerable to guessing by friends and to face recognition
Node Centrality in Complex Networks proposes new metrics for analysing
highly dynamic systems. If there's an epidemic of flu, should you close down the
schools or the subway? (video blog news)
Prediction in Dynamic Human Contact Networks examines empirical methods for
predicting centrality of individuals in different contact networks that evolve
- Eight Friends
are Enough: Social Graph Approximation via Public Listings shows how easy it
is for an outsider to work out the structure of friendships on Facebook. (For
more, see our blog on Facebook's technical privacy and its democracy theatre.)
New Strategies for
Revocation in Ad-Hoc Networks won the best paper award at ESAS07. In it we show how to
use suicide bombing for revocation in networks. Suicide attacks are found
widely in nature, from bees to helper T-cells; this model may help explain why
(press coverage here
The idea was developed further in Fast exclusion of
errant devices from vehicular networks at SECON 08.
- I was a designer of the security of Homeplug AV, an industry standard for
broadband communication over the power mains. Here's
on what we did and why; it's is a good worked example of how to do key
establishment in a real ad-hoc system. The core problem is: how can you be sure
you're recruitng the right device, rather than a similar one nearby?
- Sybil-resistant DHT
routing appeared at ESORICS 2005 and showed how we can
make peer-to-peer systems more robust against disrutpive attacks if we know
which nodes introduced which other nodes.
Infection - Smart trust for Smart Dust appeared at ICNP 2004 and presents a radically new
approach to key management in sensor and peer-to-peer networks. Peers establish
keys opportunistically and use resilience mechanisms against later node
compromise. This work challenged the assumption that authentication is largely
- The Economics of
Censorship Resistance examines when it is better for defenders to aggregate
or disperse. Should file-sharers build one huge system like gnutella and hope
for safety in numbers, or would a loose federation of fan clubs for different
bands work better?
- A keynote talk about next-generation
peer-to-peer systems at Wizards of OS in 2004
discussed how usenet might be reimplemented on a chord ring.
- A New Family of
Authentication Protocols presented our "Guy Fawkes Protocol", which lets
users sign messages using only two computations of a hash function and one
reference to a timestamping service. It led to the Tesla research on protocols
for signing digital streams.
- The Resurrecting
Duckling: Security Issues for Ad-hoc Wireless Networks was very
influential. It describes how to do key management between low-cost devices
without either the costs or privacy problems of central servers. (There's also
a journal version here.)
- The Cocaine
Auction Protocol explored how transactions can be conducted between
mutually mistrustful principals with no trusted arbitrator, while giving a high
degree of privacy against traffic analysis.
- The Eternal
Resource Locator: An Alternative Means of Establishing Trust on the World Wide
Web investigated how to protect naming and indexing information and showed
how to embed trust mechanisms in html documents. It was motivated by a medical
school project to protect the electronic version of
the British National Formulary:
Books: Protecting the Distribution of Knowledge. Later work included some
how to secure a digital repository; and Jikzi, an authentication framework
for electronic publishing, on which there are
papers. (Jikzi also led to a startup.)
- The XenoService
– A Distributed Defeat for Distributed Denial of Service described
defeating DDoS attacks using a network of web hosts that can respond to an
attack on a site by replicating it rapidly and widely. It used Xen, a
hypervisor developed at Cambridge for distributed hosting, which led to
Reliability of security systems
I have been interested for many years in how security systems fail in real
life. This is a prerequisite for building robust secure systems; many security
designs are poor because they are based on unrealistic threat models. This work
began with a study of automatic teller machine fraud, and expanded to other
applications as well. It provides the central theme of my book. I also have a
separate page on bank
security which gathers together all our papers on fraud in payment systems
with some additional material.
with the enemy on network management describes a project to develop a
version of Quagga for software defined networking research, called QuaSM. It
appeared at Security Protocols 2014. Authentication
for Resilience: the Case of SDN discusses the authentication problems we
need to solve if we're to move software defined networks out of the data centre
into more heterogeneous environments, and appeared at Security Protocols 2013.
- Rendezvous is a
prototype search engine for code, which we hope will bring reverse engineering
into the 21st century (blog).
- In PIN Skimmer:
Inferring PINs Through The Camera and Microphone we show that software on
your smartphone can work out what PIN you enter on your phone by watching your
face through the camera and listening for the clicks as you type (blog BBC CNN).
- Chip and Skim: cloning
EMV cards with the pre-play attack discloses a family of vulnerabilities in
EMV, the protocol underlying Chip and PIN payments. This may explain many
disputed transactions that look like card cloning and which the banks often
won't refund to fraud victims (blog BBC FT PCW Schneier))
Certification Systems Fail: Lessons from the Ware Report analyses failures
in the Common Criteria, FIPS 140 and other certification mechanisms by studying
lessons from the banking industry.
a research platform deconflating hardware virtualization and protection is
the first paper on a large
project we have with SRI to build a CPU supporting capabilities, port
FreeBSD to it, and build some demonstrator apps exploring the costs and
benefits of CPUs with hardware support for more fine-grained access control (Schneier).
Practical Policy Enforcement for Android Applications describes how to
repackage Android apps to add user sandboxing and policy-enforcement code (source code).
and privacy implications of consumer payment innovation discusses what
threats to competition, privacy and payment security might arise as a result of
mobile innovation; I gave it at the Fed's biennial Payment
Systems Conference (slides blog).
birthday present every eleven wallets? is the first proper study of the
security of customer-selected bank PINs, and documents all sorts of bad stuff
(blog, press, blog).
controls the off switch? describes the strategic vulnerability created by
the UK plan to replace 47m gas and electricity meters with ‘smart
meters’ that can be switched off remotely. There are further papers on
SCADA security engineering here, here, here, here and here.
- A recurrring theme is the vulnerabilities in the EMV payment system, known
in the UK as Chip
and PIN. We won an award
for a paper
describing a man-in-the-middle attack that allows a stolen card to be used with
any pin. There was a TV
see also ZDnet,
the Register, Bruce
Schneier, the press
Rather than fixing the problem, the UK banks sought
our research; see comment in
News, Slashdot, Ars
- Other recent work on problems with bank systems includes Can We Fix the
Security Economics of Federated Authentication? which explores how we can
deal with a world in which your mobile phone contains your credit cards, your
driving license and even your car key (blog); a paper on whether
EMV is bad for innovation; a paper on Verified by
VISA, the mechanism that asks for your card password when you shop online;
and a tech report On
the Security of Internet Banking in South Korea.
- Optimised to
Fail: Card Readers for Online Banking documents the shortcomings of the
CAP card readers used for online banking; see also our blog, press
coverage and the later journal
inside the box: system-level failures of tamper proofing documented serious
vulnerabilities in Chip and PIN payment terminals and won the Best Practical Paper award at
the 2008 Oakland
conference. It was also featured on Newsnight; see the video
and the viewers'
comments. Here are some frequently
asked questions, our press
release, and coverage in the Register,
blog and the Telegraph. My paper Failures on
Fraud appeared in a central bankers' magazine and argued that all this is
yet another symptom of the failure of bank regulation.
snooping dragon: social-malware surveillance of the Tibetan movement
explains how the Chinese intelligence services compromised many of the
computers at the Dalai Lama's private office, and what this means for
information security (also slides).
- Why Cryptosystems
Fail was my first widely-cited paper and the first on what goes wrong with
payment systems. This version appeared at ACMCCS 93 and explains how ATM fraud
was done in the early 1990s.
Computer Security – Nine Principles took this work further, and
examines the problems with relying on cryptographic evidence. The recent
introduction of EMV ('chip and PIN') was supposed to fix the problem, but
and Chips documents protocol weaknesses in EMV,
and A Note on EMV
Secure Messaging in the IBM 4758 CCA documents even
Man-in-the-Middle Defence shows how to turn protocol weaknesses to
advantage. See my
paper RFID and
the Middleman for the likely next wave of frauds.
- On a New Way to
Read Data from Memory describes techniques we developed that use lasers to
read out memory contents directly from a chip, without using the read-out
circuits provided by the vendor. The work builds on methods described in Optical Fault
Induction Attacks, which showed how laser pulses could be used to induce
faults in smartcards that would leak secret information. That paper appeared at
CHES 2002; it made the
front page of the New York
Times and also got covered by slashdot.
It led to the field of semi-invasive attacks on semiconductors, pioneered by my
then research student Sergei Skorobogatov.
- After we discovered the above attacks, we developed a CPU technology that
uses redundant failure-evident logic to thwart attacks based on fault induction
or power analysis. Our
on this technology won an award at Async 2002. Our journal
Self-Checking Asynchronous Logic for Smart Card Applications, has more.
- Our classic paper on hardware security, Tamper Resistance
– A Cautionary Note, describes how to penetrate the smartcards and
secure microcontrollers of the mid-1990s. It kicked off the modern academic
study of hardware security and won a Best Paper award. Our second paper on the
subject was Low Cost Attacks on
Tamper Resistant Devices, which describes a number of further tricks. See
also the home page of our hardware security
laboratory, and Markus Kuhn's page of links to hardware
- On the
Reliability of Electronic Payment Systems describes work I did to help
develop prepayment utility metering, which made possible the electrification of
millions of homes in Africa. It appeared in the May 1996 issue of the IEEE
Transactions on Software Engineering. An ealier version, entitled Cryptographic
Credit Control in Pre-Payment Metering Systems, appeared at Oakland 95. A
later paper on this
subject discussed how we could apply what we'd learned to support utility
meter interworking in the UK after deregulation.
- On the Security
of Digital Tachographs successfully predicted how the introduction of
smartcard-based digital tachographs throughout Europe from 2005 would affect
fraud and tampering.
- How to Cheat
at the Lottery reports a novel and, I hope, entertaining experiment in
software requirements engineering.
- The Grenade
Timer describes a novel way to protect low-cost processors against
denial-of-service attacks, by limiting the number of cycles an application can
- The Millennium
Bug – Reasons Not to Panic describes our experience in coping with
the bug at Cambridge University and elsewhere. This paper correctly predicted
that the bug wouldn't bite very hard. Journalists were not interested, despite
a major press
release by the University: I later discussed what we could learn from the
incident in a radio
interview with Stephen Fry.
- The Memorability
and Security of Passwords -- Some Empirical Results tackles an old problem
- how do you train users to choose passwords that are easy to remember but hard
to guess? We did a randomized controlled trial with a few hundred first year
science students which confirmed some folk beliefs, but debunked some others.
This became one of the classic papers on security usability.
- Murphy's law,
the fitness of evolving species, and the limits of software reliability
applies the techniques of statistical thermodynamics to the failure modes of
any complex system that evolves under testing. It provides a common mathematical
model for the reliability growth of complex computer systems and for biological
evolution. Its findings are in close agreement with empirical data, and it
work in security economics.
Policies play a central role in secure systems engineering. They provide a
concise statement of the kind of protection a system is supposed to achieve.
This article is a security policy tutorial.
cryptography with biometrics shows that in those applications where you can
benefit from biometrics, you often don't need a large central database (as
proposed for Britain's ID card). There are
smarter and less privacy-invasive ways to arrange things.
The papers on physical security by Roger Johnston's team are
also definitely worth a look, and there's an old leaked copy of the NSA Security Manual
that you can download (also as latex).
Robustness of cryptographic protocols
Many security system failures are due to poorly designed protocols, and this
has been a Cambridge interest for many years. Some relevant papers follow.
- API Level
Attacks on Embedded Systems are a powerful way to attack cryptographic
processors, and indeed any systems where more trusted processes talk to less
trusted ones. We found that a "secure" device can often be defeated by sending
it some sequence of transactions which its designer did not expect. We've
defeated pretty well every security processor we've looked at, at least once.
This line of research started at Protocols 2000 with The Correctness of
Crypto Transaction Sets; more followed in the first edition of
my book. Robbing
the bank with a theorem prover shows how to apply advanced tools to the
problem, and ideas for future research can be found in Protocol
Analysis, Composability and Computation. For a snapshot of how this
interacts with physical security, see
our survey of
cryptographic processors, a shortened version of which appeared in the
February 2006 Proceedings of the IEEE. An up-to-date survey of API attacks can
be found in the second edition of
book. There is also an API security
FAQ and an annual
protocols and evidence: where many payment systems fail analyses why
dispute resolution is hard. In a nutshell, the systems needed to support it
properly just don't get built (blog).
for Resilience: the Case of SDN discusses the authentication problems we
need to solve if we're to move software defined networks out of the data centre
into more heterogeneous environments. It appeared at Security Protocols 2013.
- Can We Fix the
Security Economics of Federated Authentication? explores how protocols work,
or fail, at global scale. How can we deal with a world in which your mobile
phone contains your credit cards, your driving license and even your car key
– and in particular what happens when it gets stolen or infected? (blog)
Management for Substations: Symmetric Keys, Public Keys or No Keys? debunks
the proposal to mandate public-key crypto in electricity substations. In this
particular application, the right solution is usually to have no crypto at all.
- What Next
after Anonymity? argues that it isn't enough to worry about the
confidentiality of metadata (anonymity); we sometimes need to protect their
integrity as well.
Satan's Computer is a phrase Roger Needham and I coined to express
the difficulty of designing cryptographic protocols; it has recently been
popularised by Bruce Schneier (see, for example, his foreword to my book). The problem of
designing programs which run robustly on a network containing a malicious
adversary is rather like trying to program a computer which gives subtly wrong
answers at the worst possible moment.
principles for public key protocols gives a number of attacks on protocols
based on public key primitives. It also puts forward some principles which can
help us to design robust protocols, and to find attacks on other people's
designs. It appeared at Crypto 95.
- The Cocaine
Auction Protocol explores how transactions can be conducted between
mutually mistrustful principals with no trusted arbitrator, even in
environments where anonymous communications make most of the principals
- The Initial
Costs and Maintenance Costs of Protocols appeared at the 2005 Protocols
Workshop and shows how economics can enter into protocol design.
- NetCard - A
Practical Electronic Cash Scheme presents research on micropayment
protocols for use in electronic commerce. We invented tick payments
simultaneously with Torben Pedersen and with Ron Rivest and Adi Shamir; we all
presented our work at Protocols 96.
- The GCHQ
Protocol and its Problems pointed out a number of flaws in a key management
protocol promoted by GCHQ as a European alternative to Clipper, until we shot
it down with this paper at Eurocrypt 97. Many of the criticisms we developed
here also apply to the more recent, pairing-based cryptosystems.
- The Formal
Verification of a Payment System describes the first use of formal methods
to verify an actual payment protocol, which was (and still is) used in an
electronic purse product (VISA's COPAC card). This is a teaching example I use
to get the ideas of the BAN logic across to undergraduates. There is further
detailed information in a technical
report, which combines papers given at ESORICS 92 and Cardis 94.
Attack on Server Assisted Authentication Protocols appeared in Electronics
Letters in 1992. It breaks a digital signature protocol.
- On Fortifying
Key Negotiation Schemes with Poorly Chosen Passwords presents a simple way
of achieving the same result as protocols such as EKE, namely preventing
middleperson attacks on Diffie-Hellman key exchange between two people whose
shared secret could be guessed by the enemy.
Protocols have been the stuff of high drama. Citibank asked the High Court to
disclosure of certain crypto API
vulnerabilities that affect a number of systems used in banking. I wrote to
the judge opposing
this; a gagging
order was still imposed, although in slightly less severe terms than
Citibank had requested. The trial was in camera, the banks' witnesses didn't
have to answer questions about vulnerabilities, and new information revealed
about these vulnerabilities in the course of the trial may not be disclosed in
England or Wales. Information already in the public
domain was unaffected. The vulnerabilities were discovered by Mike Bond and me while acting as the
defence experts in a phantom withdrawal court case, and independently discovered
by the other side's expert, Jolyon Clulow, who later joined us as
a research student. They are of significant scientific interest, as well as being
relevant to the rights of the growing number of people who suffer phantom withdrawals from their bank
accounts worldwide. Undermining the fairness of trials and forbidding discussion
of vulnerabilities isn't the way forward (press coverage by the
Analysis and design of cryptographic algorithms
on the hash function SHA made Tiger, which Eli Biham and I designed in 1995,
a popular choice of hash function for a while. I also worked with Eli, and
with Lars Knudsen, to develop Serpent – a
candidate block cipher for the Advanced
Encryption Standard. Serpent won through to the final of the competition and
got the second largest number of votes. Another of my contributions was founding
the series of workshops on Fast Software
Other papers on cryptography and cryptanalysis include the following.
- The Dancing Bear
– A New Way of Composing Ciphers presents a new way to combine crypto
primitives. Previously, to decrypt using (say) any three out of five keys, the
keys all had to be of the same type (such as RSA keys). With my new
construction, you can mix and match - RSA, AES, even one-time pad. The paper
appeared at the 2004 Protocols Workshop; an earlier version came out at the FSE 2004 rump session.
- Two Remarks on
Public Key Cryptology is a note on two ideas I floated at talks I gave in
1997-98, concerning forward-secure signatures and compatible weak keys. The
first of these has inspired later research by others; the second gives a new
attack on public key encryption.
Practical and Provably Secure Block Ciphers: BEAR and LION shows how to
construct a block cipher from a stream cipher and a hash function. We had
already known how to construct stream ciphers and hash functions from block
ciphers, and hash functions from stream ciphers; so this paper completed the
set of elementary reductions. It also led to the "Dancing Bear" above.
- Tiger –
A Fast New Hash Function defines a new hash function, which we designed
following Hans Dobbertin's attack on MD4. This was designed to run extremely
fast on the new 64-bit processors such as DEC Alpha and IA64, while still
running reasonably quickly on existing hardware such as Intel 80486 and
Pentium (the above link is to the Tiger home page, maintained in Haifa by Eli
Biham; if the network is slow, see my UK mirrors of the Tiger paper, new and old reference
implementations (the change fixes a padding bug) and S-box generation
documents. There are also third-party crypto toolkits supporting Tiger,
such as that from Bouncy Castle).
- Minding your
p's and q's points out a number of things that can go wrong with the choice
of modulus and generator in public key systems based on discrete log. It
elucidated some of the previously classified reasoning behind the design of the
US Digital Signature Algorithm, and appeared at Asiacrypt 96.
– A New Kind of Stream Cipher shows how to do traitor tracing using
symmetric rather than public-key cryptology. The idea is to turn a stream
cipher into one with reduced key diffusion, but without compromising
security. A single broadcast ciphertext is decrypted to slightly different
plaintexts by users with slightly different keys. This paper appeared
at Fast Software
Encryption in Haifa in January 1997.
for the Optimum Correlation Attack shows that nonlinear combining functions
used in nonlinear filter generators can react with shifted copies of themselves
in a way that opens up a new and powerful attack on many cipher systems. It
appeared at the second workshop on fast software encryption.
- The Classification of
Hash Functions showed that correlation freedom is strictly stronger than
collision freedom, and shows that there are many pseudorandomness properties
other than collision freedom which hash functions may need. It appeared at
Cryptography and Coding 93.
- A Faster Attack
on Certain Stream Ciphers shows how to break the multiplex shift register
generator, which is used in satellite TV systems. I found a simple
divide-and-conquer attack on this system in the mid 1980's, a discovery that
got me "hooked" on cryptology. This paper is a refinement of that work.
- On Fibonacci
Keystream Generators appeared at FSE3, and shows how to break "FISH", a
stream cipher proposed by Siemens. It also proposes an improved cipher, "PIKE",
based on the same general mechanisms.
- Tree Functions and
Cipher Systems appeared in 1991; it points out a weakness in a proprietary
cipher that was later developed into this.
Information hiding (including Soft Tempest)
From the mid- to late-1990s, I did a lot of work on information hiding.
- Soft Tempest:
Hidden Data Transmission Using Electromagnetic Emanations must be one of
the more unexpected things we discovered. It is well known that eavesdroppers
can reconstruct digital information such as video screen content from stray
radio frequency emanations; such `Tempest attacks' were traditionally prevented
by shielding, jammers or physical distance. We discovered that the software on
a computer can control its stray electromagnetic emanations. To attack a
system, malware can hide stolen information in signals that leak and optimise
them for some combination of reception range, receiver type or even covertness.
To defend a system, a screen driver can display sensitive information using
fonts which minimise emitted RF energy. This technology was fielded in PGP and
elsewhere. You can download Tempest fonts from here.
paper on the costs and benefits of Soft Tempest in military environments
appeared at NATO's 1999 RTO meeting on infosec, while an earlier version of our
main paper, which
Finally, there's some software you can use to play your MP3s over the
radio here, a press article
and information on more recent optical tempest attacks here.
- Hollywood once hoped that copyright-marking systems would help control the
copying of videos, music and computer games. This became high drama when a paper that showed how to break
the DVD/SDMI copyright marking scheme was pulled by its authors from the Information
Hiding 2001 workshop, following legal threats from Hollywood. In fact, the
basic scheme – echo hiding – was among a number that we broke in
1997. The attack was reported in our paper Attacks on
Copyright Marking Systems, which we published at Info Hiding 1998. We
also wrote Information
Hiding – A Survey, which appeared in Proc IEEE and is a good place to
start if you're new to the field. For the policy aspects, you might read Pam Samuelson. There is much more
about the technology on the web page of my former student Fabien Petitcolas.
- Another novel application of information hiding is the Steganographic File
System. It will give you any file whose name and password you know, but if
you do not know the correct password, you cannot even tell that a file of that
name exists in the system! This is much stronger than conventional multilevel
security, and its main function is to protect users against coercion. Two of
our students implemented SFS for Linux: a paper describing the details is here, while the code
is available here. This
functionality has since appeared in a number of crypto products.
- The threat in the 1990s by some governments to ban cryptography led to a
surge of interest in steganography – the art of hiding messages in other
messages – and then the surge of paranoia post-9/11 stoked interest in
looking for them, with nonsense
like this boosting many a bureaucrat's budget. Our paper On The Limits
of Steganography explored what can and can't be done (here's an earlier version).
- The Newton
Channel settles a conjecture of Simmons by exhibiting a high bandwidth
subliminal channel in the ElGamal signature scheme.
Security of Clinical Information Systems
There's a huge row brewing
over the government's plans to centralise medical records; the cover story is
improving care and giving us access to our records online while the real agenda
is to sell our medical data to insurance companies and drug company researchers. This follows a big row
under the last Government over the Summary Care Record, which centralises
records and makes them available to hundreds of thousands of NHS staff. To see
the history via our most recent blog posts, go here.
The NHS has a
previous prime minister's own medical records were compromised; the miscreant
got off scot-free
as it was not in the "public interest" to prosecute him. In another famous
case, Helen Wilkinson had to organise a debate
in Parliament to get ministers to agree to remove defamatory and untrue
information about her from NHS computers. The minister assured the House that
the libels had been removed; months later, they still had not been. Helen
started www.TheBigOptOut.org to
campaign for health privacy. They have been joined by medConfidential, Big Brother Watch and others.
Here are my most recent papers on the subject.
State is a report we wrote for the Joseph Rowntree Reform Trust on
the failings of public-sector IT in Britain, and how to fix them. It pointed
out that a number of health systems almost certainly break European law. There's
coverage on the BBC, in the Guardian (also here), the Mail (also
the Independent, the Telegraph, E-Health Insider and Liberty Central. This report had a lot of impact; the coalition
government promised to abolish or at least change a number of the systems we
fingered as unlawful. Both the Conservatives and the Lib Dems promised to axe
the NHS centralisation project too if they won the 2010 election; after they did
so, the name was changed but the stupidity continued.
- In I 2006 organised 23 computer science professors to write to the Health
Committee requesting an independent review of the
NHS National Programme for IT, the last big centralisation drive, as it was
visible failing. Ministers refused, and NPfIT
went on to become the largest civil-government IT project failure ever.
- I was one of the authors of a 2006 report on the safety and
privacy of children's databases, done for the UK Information Commissioner.
It concluded that government plans to link up most of the public-sector
databases that hold information on children were misguided: the proposed systems
would be both unsafe and illegal. This report got a lot of
publicity. I spoke on these issues on these
videos made by Action on Rights for Children.
- I wrote a report
for the National Audit Office on the health IT expenditure, strategies and
goals of the UK and a number of other developed countries. This showed that the
NHS National Program for IT is in many ways an outlier, and high-risk.
- Here is an article I
wrote for Drugs and Alcohol Today analysing the likely effects of the NHS
computing project on patient privacy, particularly in the rehabilitation field.
- In 2007 I acted as a Special Adviser to the House of Commons Health Select
on the Electronic Patient Record. This concluded that the NHS
computerisation project is failing to meet its core objectives, and that
patient privacy is at risk as well as operational effectiveness. I was a
Special Adviser to the Committee. (See the parliamentary
debate on the report, press comment, and
an article on the implications
for HIV treatment.)
- Patient confidentiality
and central databases appeared in the February 2008 British Journal of
General Practice, calling on GPs to encourage patients to opt out of the NHS
care records service.
- System security for
cyborgs discusses technical, ethical and security-economics issues to do
with implantable medical devices.
Civil servants started pushing for online access to everyone's records in 1992
and I got involved in 1995, when I started consulting for the British Medical
Association on the safety and privacy of clinical information systems. Back
then, the police were given access to all drug prescriptions, after the
government argued that they needed it to catch doctors who misprescribed
heroin. The police got their data, but they didn't
catch Harold Shipman,
and no-one was held accountable. The NHS slogan in 1995 was `a unified electronic patient record, accessible to
all in the NHS'. The BMA campaigned against this, arguing that it would destroy
Security in Clinical Information Systems was published by the BMA in
January 1996. It sets out rules that uphold the principle of patient consent
independently of the details of specific systems. It was the medical
profession's initial response to the safety and privacy problems posed by
centralised NHS computer systems.
Update on the BMA Security Policy appeared in June 1996 and tells the story
of the struggle between the BMA and the government, including the origins and
development of the BMA security policy and guidelines.
- There are comments made
at NISSC 98 on the healthcare protection profiles being developed by NIST for
the DHHS to use in regulating health information systems privacy, which made a
number of mistaken assumptions about threats and protection mechanisms.
on the Caldicott Report raises a number of issues about the report of the
Caldicott Committee, which was set up by the Major government to kick the
medical privacy issue into touch until after the 1997 election. Its members
failed to understand that medical records from which the names have been
removed, but where NHS numbers remain, are not anonymous – as large
numbers of NHS staff need to map names to numbers in order to do their
technology in medical practice: safety and privacy lessons from the United
Kingdom provided an overview of the safety and privacy problems we
encountered in UK healthcare computing in the mid-90s for readers of the
Australian Medical Journal.
DeCODE Proposal for an Icelandic Health Database analyses a proposal to
collect all Icelanders' medical records into a single database. I evaluated
this for the Icelandic Medical Association and concluded that the proposed
security wouldn't work. The company running it soon hit financial
problems and later filed for bankruptcy. The ethical issues were a
Supreme Court allowed a woman to block access to her father's
records because of the information they may reveal about her (see analysis).
This effectively killed the vision of having the whole population on a database.
I also wrote an analysis
of security targets prepared under the Common Criteria for the evaluation of
this database. See also BMJ
correspondence and an article by Einar
System Security – Interim Guidelines appeared in the British Medical
Journal on 13th January 1996. It advises healthcare professionals on prudent
security measures for clinical data. The most common threat is that private
investigators use false-pretext telephone calls to elicit personal health
information from assistant staff.
Security Policy Model for Clinical Information Systems appeared at the 1996
IEEE Symposium on Security and Privacy. It presents the BMA policy model to the
computer security community in a format comparable to policies such as
Bell-LaPadula and Clark-Wilson. It had some influence on later US health
privacy legislation (the Kennedy-Kassebaum Bill, now HIPAA).
Wide Networking and Patient Confidentiality appeared in the British Medical
Journal in July 1995 and set out some early objections to the government's
health network proposals.
Confidentiality &ndash At Risk from NHS Wide Networking went into somewhat
more detail, particularly on the security policy aspects. It was presented at
Health Care 96.
with the NHS Cryptography Strategy points out a number of errors in, and
ethically unacceptable consequences of, a report on
cryptography produced for the Department of Health. These comments formed the
BMA's response to that report.
In 1996, the Government set up the Caldicott Committee to study the
matter. Their report
made clear that the NHS was already breaking confidentiality law by sharing
data without consent; but the next Government
and again) to
give itself the power to share health data as the Secretary of State saw
fit. (We objected
and pointed out
the problems the
bill could cause; similar sentiments were expressed in
a BMJ editorial,
and a Nuffield
analysis, and BMJ
and here. Ministers
claimed the records were needed for cancer registries: yet cancer researchers
work with anonymised data in other countries – see
There was a storm of protest in the press: see
the New Statesman,
Register. But that died down; the measure has now been consolidated
as sections 251
and 252 of the NHS Act 2006, the Thomas-Walport review blessed nonconsensual
access to health records (despite FIPR pointing out that this was
illegal – a view later supported by the European Court). A government
committee, the NHS Information Governmance
Board, was set up oversee this lawbreaking, and Dame Fiona is being wheeled out once more. Centralised,
nonconsensual health records not only contravene the I v Finland judgement but
of Helsinki on ethical principles for medical research and
the Council of
Europe recommendation no R(97)5 on the protection of medical data.
Two health IT papers by colleagues deserve special mention. Privacy in clinical
information systems in secondary care describes a hospital system
implementing something close to the BMA security policy (it is described in
more detail in a special issue of the Health
Informatics Journal, v 4 nos 3-4, Dec 1998, which I edited). Second, Protecting Doctors'
Identity in Drug Prescription Analysis describes a system designed to
de-identify prescription data for commercial use; although de-identification
usually does not protect patient privacy very well, there are exceptions, such
as here. This system led to a court case, in which the government tried to stop
its owner promoting it – as it would have competed with their (less
privacy-friendly) offerings. The government lost: the Court of Appeal decided
that personal health information can be used for research without patient
consent, so long as the de-identification is done competently.
Resources on what's happening in the USA – where
the stimulus bill has made medical privacy a very live issue – include
many NGOs: Patient Privacy Rights may have
been the most influential, but see also EPIC, the Privacy Rights
Clearinghouse, the Citizens' Council on Health Care, the Institute for Health Freedom. and CDT. Older resources include
an NAS report entitled For the Record: Protecting
Electronic Health Information, a report by the Office of Technology
Assessment, a survey of the uses of
de-identified records for the DHHS, and a GAO report on their use
in Medicare. For information on what's happening in the German-speaking world,
Bleumer's web page. As for the basic science, the American
Statistical Association has a good collection of links to papers on
inference control, also known as statistical security – the protection of
Public policy issues
I chair the Foundation for Information Policy
Research, the UK's leading Internet policy think tank, which I helped set
up in 1998. We are not a lobby group; our enemy is ignorance rather than the
government of the day, and our mission is to understand IT policy issues and
explain them to policy makers and the press. Here's an overview of the issues as we saw them in 1999, and a video
of how we saw them ten years later in 2008. Some highlights of our work follow.
- Privacy has become a big theme recently thanks to the Communications
Data Bill, against which we have been organising resistance.
In the last parliament, our Database
State report on the failings of public-sector IT in Britain, and how to fix
them, got massive press coverage: the BBC, the Guardian (also here), the Mail (also
the Independent, the Telegraph, E-Health Insider and Liberty Central. This followed an earlier report on children's databases,
and the many other activities described above. Both main
opposition parties promised to kill or change at least some of these systems,
and after they won power in the 2010 election their coalition agreement spelled
the end of the ContactPoint children's database, and of ID cards. The subsequent
review by my FIPR
colleague Eileen Munro also sealed the fate of eCAF, another central children's
- Waste of Public Money is another objection to the bad
government systems that undermine our privacy. Other wasteful systems include smart
meters which look set to cost billions without achieving anything useful (blog).
- Identity Cards were a clever political move by Blair; they
divided the Conservatives in 2004-5. I testified
to the Home Affairs committee in 2004 that they would not work as advertised,
and contributed to the LSE Report that
spelled this out in detail. I'd produced numerous previous pieces in response
to government identity consultations, on aspects such as smartcards and PKI. There's more
in my book (ch. 6).
- Internet Censorship is a growing problem, and not just in
developing countries; I've been on the receiving end more than once. In 1995, I invented the first
censorship-resistant system, the Eternity
Service; this was a precursor of later file-sharing systems (see above), and we've also written on the economics of
censorship resistance. But despite the technical difficulties and
collateral costs of content filtering, governments aren't giving up. From 2006
to 2008, I was a principal investgator for the OpenNet Initiative which monitors
Internet filtering worldwide. Shifting
Borders reviewed the state of play in late 2007, and appeared in Index
on Censorship; Tools
and Technology of Internet Filtering goes into more technical detail and
appeared in Access Denied. The
political action now is about Internet blocking.
Consumer Protection: FIPR also brought together legal and computing
experts to deconstruct the fashionable late-1990s notion that ‘digital
certificates’ would solve all the problems of e-commerce and e-government.
Anyone inclined to believe such nonsence should read Electronic
Commerce – Who Carries the Risk of Fraud?. Other work in this thread
include FIPR's responses to consultations on smartcards, the electronic signature
directive and the ecommerce
- More recently we have been alarmed at the erosion of consumer rights as a
result of the introduction of chip and PIN cards. The technical sections above describe how frauds happen; the flip side of the story is how
the banks escape liability. Our analysis of the failings of the
Financial Ombudsman Service remains unanswered; see also FIPR's submission
on Personal Internet
Security (with which the House of Lords basically agreed)
and the National Payments Plan. FIPR
now takes the view that the only way to fix
consumer protection is to replace public action with private action, by changing
the rules on costs so that consumers can enforce their rights in court without
risking horrendous costs orders if they lose.
- The RIP Act, the Crypto Wars and Key Escrow: I got engaged
in technology policy thanks to attempts in the 1990s by governments (led by the
USA) to control the use of cryptography. In 1995, I wrote Crypto in Europe
– Markets, Law and Policy. This surveyed the uses of cryptography in
Europe and discussed the shortcomings of crypto policy; I pointed out that law
enforcement communications intelligence was mostly about traffic analysis and
criminal communications security was mostly traffic security. This view was
heretical at the time but is now orthodoxy. The Risks of Key Recovery,
Key Escrow, and Trusted Third-Party Encryption became the most widely-cited
publication on key escrow. It examines the technical risks, costs, and
implications of deploying systems that would satisfy government wishes. It was
originally presented as testimony to the US Senate, and then also to the Trade
and Industry Committee of the UK House of Commons, together with a further
piece I wrote, The
Risks and Costs of UK Escrow Policy.
- The GCHQ
Protocol and its Problems pointed out a number of serious defects in the protocol
that the British government used to secure its electronic mail, and which it
wanted everyone else to use too. This paper appeared at Eurocrypt 97 and it
replies to GCHQ's response to an earlier
version of our paper. Our analysis stopped the protocol being widely
Global Trust Register is a book of the fingerprints of the world's most
important public keys. It thus implements a top-level certification authority,
but using paper and ink rather than electronics. DTI proposals for mandatory
licensing of cryptographic services would have banned this book; that fact
enabled me to visit Culture Secretary Chris Smith at a critical point in the
crypto wars and get crypto policy referred to Cabinet when otherwise it would
have remained the province of the civil servants.
This was all part of a campaign that FIPR ran to limit the scope of the Regulation of Investigatory Powers Act.
Originally this would have allowed the police to obtain, without warrant, a
complete history of everyone's web browsing activity (as this would have been
‘communications data’); FIPR got the House of Lords to limit this to
the identity of the machines involved in a communication, rather than the URLs
of the web pages. But the RIP Act still made it into law and has had a number of
the bad effects we predicted at the time. See for example
I wrote on the history of the Act following
imprisonment of a mentally-ill man under the Act for refusing to hand over
his PGP passphrase when the Met's terror squad told him to.
- These issues have come round once more with GCHQ's Interception
Modernisation Programme, a plan to centralise all traffic data first in a
central database and more recently in a system of federated databases maintained
by communications service providers. FIPR wrote a response to a Home Office
consultation on this, and another response to one on the orders and
codes of practice for interception. We also commented on the Cabinet
Office's (actually GCHQ's) inappropriate proposals to secure government systems.
- Terrorism: A page with Comments on Terrorism
explains why many of the measures that various people have been trying to sell
since the 11th September attacks are unlikely to work as promised. Much
subsequent policy work has been made harder by assorted salesmen, centralisers,
rent-seekers and chancers talking about terror; I testified against police
attempts to increase pre-charge detention to ninety days with the implausible
claim that they needed more time to decrypt seized data. We must constantly push
back on the scaremongers; here for example is a video I did on the effects
- Export Control: In 2001-02, FIPR persuaded the Lords to
amend the Export
Control Bill. This bill was designed to give ministers the power to license
intangible exports. It was the result of US lobbying of Tony Blair in 1997;
back then, UK crypto researchers could put source code on our web pages while
our US colleagues weren't allowed to. In its original
form, its provisions were so broad that it would have given ministers the
power of pre-publication review of scientific papers. We defeated the Government
in the House of Lords by 150-108, following a hard campaign – see press
coverage in the BBC,
Scientist, the Guardian
and the Economist, and an article on free
speech I wrote for IEEE Computing. But the best quote I
have is also the earliest. The first book written on cryptology in English, by
Bishop John Wilkins in 1641, remarked that ‘If all those
useful Inventions that are liable to abuse, should therefore be concealed,
there is not any Art or Science which might be lawfully profest’
This issue revived in 2003, with a government attempt to wrest back using
regulations much of what they conceded in parliament. FIPR fought back
and extracted assurances
from Lord Sainsbury about the interpretation of regulations made under the
Act. Without our campaign, much scientific collaboration would have become
technically illegal, leaving scientists open to arbitrary harrassment. Much
credit goes to the Conservative frontbencher Doreen
Miller, Liberal Democrat frontbencher Margaret
Sharp, and the then President of the Royal Society Bob May,
who made his maiden speech in the Lords on the issue and marshalled the
crossbenchers. We are very grateful for their efforts.
- Trusted Computing was a focus in 2002-03. I wrote a Trusted Computing FAQ
that was very widely read, followed by a study of the
competition policy aspects of this technology. This led inter alia to a symposium organised by the German government which
in turn pushed the Trusted Computing Group into incorporating, admitting small
companies, and issuing implementation guidelines. Trusted Computing appears to
have fizzled out because Microsoft couldn't get remote attestation to work; the
only thing the TPM is used for in Windows Vista is hard disk encryption.
- IP Enforcement: Our top priority in 2003-04 was the EU IPR enforcement
directive, which has been succinctly described as DMCA on
steroids and criticised by
distinguished lawyers. Our lobbying got it amended to remove
criminal sanctions for patent infringement and legal protection for devices such
as RFID tags. This law was supported by the music industry,
the luxury brands, and (initially) Microsoft, while the coalition that we
put together to oppose it included the phone companies, the supermarkets, the
generic drugmakers, the car parts industry, smaller software firms and the free
software community. The press was sceptical – in Britain, France and even America. The issue was even linked to a boycott of
Gillette. There is more on my blog.
- This was a watershed in copyright history: the IP lobby was never going to
be stopped by fine words, only by another lobby pushing in the other direction,
and the Enforcement Directive was when that first came together. It also led to
the birth of EDRI, European Digital Rights, a
confederation of European digital-rights NGOs, whose establishment was one of
FIPR's significant achievements. EDRI's first campaign was against the IP
Enforcement Directive; afterwards FIPR and EDRI established a common position on intellectual
property. Since then I have given evidence to the Gowers Review of IP
and a parliamentary
committee on DRM; however the lead UK NGO on IP nowadays is the Open Rights Group.
I am one of the professors elected to serve for 2015–19 on Council,
Cambridge University's governing body, and am also on our Research
I served earlier from 2003-10 when I stood for election because of a proposal
that most of the intellectual property generated by faculty members –
from patents on bright ideas to books written up from lecture notes –
would belong to the university rather than to its creator. There were already
unpleasant incidents around IP (see for example Mike Clark's
to stop such things happening again, we founded
the Campaign for Cambridge
approved a policy according to which academics keep copyright but the
University gets 15% of patent royalties. I
got re-elected in
2006, and in my second term
we won an
to protect academic
freedom. For more, see
from the Oxford Magazine, and
History of Cambridge University. From 2013-4 I was on
our Board of Scrutiny.
My CV is here.
I'm a Fellow of the Churchill College, the Royal Society, the Royal Academy of Engineering, the Institution of Engineering and Technology, the
Institute of Mathematics and its
Applications, and the Institute of
Physics. My h-index is tracked here. As for
my academic genealogy, my thesis adviser was Roger Needham; his was Maurice Wilkes; then it
runs back through Jack Ratcliffe, Edward Appleton,
JJ Thomson, Lord
Rayleigh, Edward Routh, William Hopkins, Adam Sedgwick, Thomas
Postlethwaite, Stephen Whisson, Walter
Smith, Roger Cotes, Isaac Newton, Isaac Barrow and Vincenzo Viviani to Galileo Galilei.
Finally, here is my PGP
key. If I revoke this key, I will always be willing to explain why I have
done so provided that the giving of such an explanation is lawful. (For
more, see FIPR.)
The second edition is
now out! You can order it from Amazon.com and Amazon.co.uk.
Security engineering is about building systems to remain dependable in the face
of malice, error or mischance. As a discipline, it focuses on the tools,
processes and methods needed to design, implement and test complete systems,
and to adapt existing systems as their environment evolves. My book has become
the standard textbook and reference since it was published in 2001. You can
download both the first and second editions without charge here.
Security engineering is not just concerned with infrastructure matters such as
firewalls and PKI. It's also about specific applications, such as banking and
medical record-keeping, and about embedded systems such as automatic teller
machines and burglar alarms. It's usually done badly: it often takes several
attempts to get a design right. It is also hard to learn: although there were
good books on a number of the component technologies, such as cryptography and
operating systems, there was little about how to use them effectively, and even
less about how to make them work together. Most systems don't fail because the
mechanisms are weak, but because they're used wrong.
My book was an attempt to help the working engineer to do better. As well as
the basic science, it contains details of many applications – and lot of
case histories of how their protection failed. It describes a number of
technologies which aren't well covered elsewhere. The first edition was pivotal
in founding the now-flourishing field
of information security
economics: I realised that the narrative had to do with incentives and
organisation at least as often as with the technology. The second edition
incoporates the economic perspectives we've developed since then, and new
perspectives from the psychology of security, as well as updating the
technological side of things.
I only referee for open publications, so I discard emails asking for reports
for journals that sit behind a paywall. I also usually discard emails sent by
people's secretaries: if you can't be bothered to email me yourself, then I
can't be bothered to answer myself either.
If you want to do a PhD, please read our web pages first; we get lots
of CV spam which we delete. I also discard emails that ask for internships; we
can't employ overseas students on Tier 4 visas any more. If you're interested
in coming as an undergrad, have a look at our video.