When I read about cryptography before computers, I sometimes wonder why people did this and that instead of something a bit more secure. We may ridicule portable encryption systems based on monoalphabetic or even simple polyalphabetic ciphers but we may also change our opinion after actually trying it for real.
Continue reading "Perfectly" Encrypt 50 Letters By Hand
Reading this may harm your computer
David Modic and I have just published a paper on The psychology of malware warnings. We’re constantly bombarded with warnings designed to cover someone else’s back, but what sort of text should we put in a warning if we actually want the user to pay attention to it?
To our surprise, social cues didn’t seem to work. What works best is to make the warning concrete; people ignore general warnings such as that a web page “might harm your computer” but do pay attention to a specific one such as that the page would “try to infect your computer with malware designed to steal your bank account and credit card details in order to defraud you”. There is also some effect from appeals to authority: people who trust their browser vendor will avoid a page “reported and confirmed by our security team to contain malware”.
We also analysed who turned off browser warnings, or would have if they’d known how: they were people who ignored warnings anyway, typically men who distrusted authority and either couldn’t understand the warnings or were IT experts.
Anatomy of Passwords
Passwords have not really changed since they were first used. Let’s go down the memory lane a bit and then analyse how password systems work and how they could be improved. You may say – forget passwords, OTP is the way forward. My next question would then be: So why do we use OTP in combination with passwords when they are so good?
Continue reading Anatomy of Passwords
Crypto festival video
We had a crypto festival in London in London in November at which a number of cryptographers and crypto policy folks got together with over 1000 mostly young attendees to talk about what might be done in response to the Snowden revelations.
Here is a video of the session in which I spoke. The first speaker was Annie Machon (at 02.35) talking of her experience of life on the run from MI5, and on what we might do to protect journalists’ sources in the future. I’m at 23.55 talking about what’s changed for governments, corporates, researchers and others. Nick Pickles of Big Brother Watch follows at 45.45 talking on what can be done in terms of practical politics; it turned out that only two of us in the auditorium had met our MPs over the Comms Data Bill. The final speaker, Smari McCarthy, comes on at 56.45, calling for lots more encryption. The audience discussion starts at 1:12:00.
2013 Capsicum year in review
It’s been a busy year for Capsicum, practical capabilities for UNIX, so a year-end update seemed in order:
The FreeBSD Foundation and Google jointly funded a Capsicum Integration Project that took place throughout 2013 — described by Foundation project technical director Ed Maste in a recent blog article. Pawel Jakub Dawidek refined several Capsicum APIs, improving support for ioctls and increasing the number of supported capability rights for FreeBSD 10. He also developed Casper, a helper daemon that provides services (such as DNS, access to random numbers) to sandboxes — and can, itself, sandbox services. Casper is now in the FreeBSD 11.x development branch, enabled by default, and should appear in FreeBSD 10.1. The Google Open Source Program Office (OSPO) blog also carried a September 2013 article on their support for open-source security, featuring Capsicum.
Capsicum is enabled by default in the forthcoming FreeBSD 10.0 release — capability mode, capabilities, and process descriptors are available in the out-of-the-box GENERIC kernel. A number of system services use Capsicum to sandbox themselves — such as the DHCP client, high-availability storage daemon, audit log distribution daemon, but also command-line tools like kdump and tcpdump that handle risky data. Even more will appear in FreeBSD 10.1 next year, now that Casper is available.
David Drysdale at Google announced Capsicum for Linux, an adaptation of Linux to provide Capsicum’s capability mode and capabilities, in November 2013. David and Ben Laurie visited us in Cambridge multiple times this year to discuss the design and implementation, review newer Capsicum APIs, and talk about future directions. They hope to upstream this work to the Linux community. Joris Giovannangeli also announced an adaptation of Capsicum to DragonFlyBSD in October 2013.
Over the summer, Mariusz Zaborski and Daniel Peryolon were funded by Google Summer of Code to work on a variety of new Capsicum features and services, adapting core UNIX components and third-party applications to support sandboxing. For example, Mariusz looked at sandboxing BSD grep: if a vulnerability arises in grep’s regular-expression matching, why should processing a file of malicious origin yield full rights to your UNIX account?
In May 2013, our colleagues at the University of Wisconsin, Madison, led by Bill Harris, published a paper at the IEEE Symposium on Security and Privacy (“Oakland”) on “Declarative, Temporal, and Practical Programming with Capabilities” — how to model program behaviour, and automatically transform some classes of applications to use Capsicum sandboxing. We were very pleased to lend a hand with this work, and feel the art of programming for compartmentalisation is a key research challenge. We also collaborated with folk at SRI and Google on a a workshop paper developing our ideas about application compartmentalisation, which appeared at the Security Protocols Workshop here in Cambridge in March 2013.
Google and the FreeBSD Foundation are committed to further work on Capsicum and its integration with applications, and research continues on how to apply Capsicum at several institutions including here at Cambridge. We hope to kick off a new batch of application adaptation in coming months — as well as integration with features such as DNSSEC. However, we also need your help in adapting applications to use Capsicum on systems that support it!
WEIS 2014 call for papers
Next year’s Workshop on the Economics of Information Security (WEIS 2014) will be at Penn State on June 23–24. The call for papers is now out; papers are due by the end of February.
It will be fascinating to see what effects the Snowden revelations will have on the community’s thinking about security standards and regulation, the incentives for information sharing and cooperation, and the economics of privacy, to mention only three of the workshop’s usual topics. Now that we’ve had six months to think things through, how do you think the security game has changed, and why? Do we need minor changes to our models, or major ones? Are we in the same policy world, or a quite different one? WEIS could be particularly interesting next year. Get writing!
Your medical records – now on sale
Your medical records are now officially on sale. American drug companies now learn that MedRed BT Health Cloud will provide public access to 50 million de-identified patient records from UK.
David Cameron announced in 2011 that every NHS patient would be a research patient, with their records opened up to private healthcare firms. He promised that our records would be anonymised and we’d have a right to opt out. I pointed out that anonymisation doesn’t work very well (as did the Royal Society) but the Information Commissioner predictably went along with the charade (and lobbyists are busy fixing up the new data protection regulation in Brussels to leave huge loopholes for health service management and research). The government duly started to compel the upload of GP data, to join the hospital data it already has. During the launch of a medical confidentiality campaign the health secretary promised to respect existing opt-outs but has now reneged on his promise.
The data being put online by BT appear to be the data it already manages from the Secondary Uses Service, which is mostly populated by records of finished consultant episodes from hospitals. These are pseudonymised by removing names and addresses but still have patient postcodes and dates of birth; patient views on this were ignored. I wonder if US purchasers will get these data items? I also wonder whether patients will be able to opt out of SUS? Campaigners have sent freedom of information requests to hundreds of hospitals to find out; so we should know soon enough.
Don't believe what you read in the papers
Yesterday the heads of “MI5”, “MI6” and GCHQ appeared before the Intelligence Security Committee of Parliament. The uncorrected transcript of their evidence is now online (or you can watch the video).
One of the questions fielded by Andrew Parker (“MI5”) was how many terrorist plots there had been over the past ten years. According to the uncorrected transcript (and this accords with listening to the video — question starts at 34:40) he said:
I think the number since… if I go back to 2005, rather than ten years… 7/7 is that there have been 34 plots towards terrorism that have been disrupted in this country, at all sizes and stages. I have referred publicly and previously, and my predecessors have, to the fact that one or two of those were major plots aimed at mass casualty that have been attempted each year. Of that 34, most of them, the vast majority, have been disrupted by active detection and intervention by the Agencies and the police. One or two of them, a small number, have failed because they just failed. The plans did not come together. But the vast majority by intervention.
I understand that to mean 34 plots over 8 years most but not all of which were disrupted, rather than just discovered. Of these, one or two per year were aimed at causing mass casualties (that’s 8 to 16 of them). I find it really quite surprising that such a rough guess of 8 to 16 major plots was not remarked upon by the Committee — but then they were being pretty soft generally in what they asked about.
The journalists who covered the story heard this all slightly differently, both as to how many plots were foiled by the agencies and how many were aimed at causing mass casualties!
Continue reading Don't believe what you read in the papers
A new side channel attack
Today we’re presenting a new side-channel attack in PIN Skimmer: Inferring PINs Through The Camera and Microphone at SPSM 2013. We found that software on your smartphone can work out what PIN you’re entering by watching your face through the camera and listening for the clicks as you type. Previous researchers had shown how to work out PINs using the gyro and accelerometer; we found that the camera works about as well. We watch how your face appears to move as you jiggle your phone by typing.
There are implications for the design of electronic wallets using mechanisms such as Trustzone which enable some apps to run in a more secure sandbox. Such systems try to prevent sensitive data such as bank credentials being stolen by malware. Our work shows it’s not enough for your electronic wallet software to grab hold of the screen, the accelerometers and the gyro; you’d better lock down the video camera, and the still camera too while you’re at it. (Our attack can use the still camera in burst mode.)
We suggest ways in which mobile phone operating systems might mitigate the risks. Meanwhile, if you’re developing payment apps, you’d better be aware that these risks exist.
Offender tagging 2.0
Three of our clients have been acquitted of tampering with curfew tags after the Ministry of Justice and G4S were unwilling to have an independent forensic team examine their evidence. This brings to five the number of tag-tampering prosecutions that have been withdrawn or collapsed when the defence says “Right, prove it then.” I reported the first case here.
The three latest matters were high-profile terrorism cases, involving three of the nine men tagged under the new Terrorism Prevention and Investigation Measure (TPIM) – a kind of national-security ASBO handed out by MI5, and which had already been criticised by David Anderson QC, the government’s independent reviewer of terrorism legislation, for low standards of proof. Unlike a normal ASBO which a court gives “on the balance of probabilities”, you can get a TPIM if the Home Secretary declares she has a “reasonable suspicion”.
The Ministry of Justice should perhaps, when they let the tagging contracts, have read our 1994 paper on the John Munden case, or the post here about the similar case of Jane Badger. If you’re designing a system one of whose functions is to provide evidence, you’d better design it to withstand hostile review. “Trust us” doesn’t cut it in criminal trials, and neither does “I’m afraid that’s commercially confidential.”