Category Archives: Authentication

The Pre-play Attack in Real Life

Authentication, Banking security, Cryptology, Cybercrime, Legal issues, News coverage, Protocols, Security economics

Recently I was contacted by a Falklands veteran who was a victim of what appears to have been a classic pre-play attack; his story is told here.

Almost ten years ago, after we wrote a paper on the pre-play attack, we were contacted by a Scottish sailor who’d bought a drink in a bar in Las Ramblas in Barcelona for €33, and found the following morning that he’d been charged €33,000 instead. The bar had submitted ten transactions an hour apart for €3,300 each, and when we got the transaction logs it turned out that these transactions had been submitted through three different banks. What’s more, although the transactions came from the same terminal ID, they had different terminal characteristics. When the sailor’s lawyer pointed this out to Lloyds Bank, they grudgingly accepted that it had been technical fraud and refunded the money.

In the years since then, I’ve used this as a teaching example both in tutorial talks and in university lectures. A payment card user has no trustworthy user interface, so the PIN entry device can present any transaction, or series of transactions, for authentication, and the customer is none the wiser. The mere fact that a customer’s card authenticated a transaction does not imply that the customer mandated that payment.

Payment by phone should eventually fix this, but meantime the frauds continue. They’re particularly common in nightlife establishments, both here and overseas. In the first big British case, the Spearmint Rhino in Bournemouth had special conditions attached to its license for some time after a series of frauds; a second case affected a similar establishment in Soho; there have been others. Overseas, we’ve seen cases affecting UK cardholders in Poland and the Baltic states. The technical modus operandi can involve a tampered terminal, a man-in-the-middle device or an overlay SIM card.

By now, such attacks are very well-known and there really isn’t any excuse for banks pretending that they don’t exist. Yet, in this case, neither the first responder at Barclays nor the case handler at the Financial Ombudsman Service seemed to understand such frauds at all. Multiple transactions against one cardholder, coming via different merchant accounts, and with delay, should have raised multiple red flags. But the banks have gone back to sleep, repeating the old line that the card was used and the customer PIN was entered, so it must all be the customer’s fault. This is the line they took twenty years ago when chip and pin was first introduced, and indeed thirty years ago when we were suffering ATM fraud at scale from mag-strip copying. The banks have learned nothing, except perhaps that they can often get away with lying about the security of their systems. And the ombudsman continues to claim that it’s independent.

Interop: One Protocol to Rule Them All?

Academic papers, Authentication, Cryptology, Legal issues, Politics, Privacy technology, Protocols, Security economics, Security psychology

Everyone’s worried that the UK Online Safety Bill and the EU Child Sex Abuse Regulation will put an end to end-to-end encryption. But might a law already passed by the EU have the same effect?

The Digital Markets Act ruled that users on different platforms should be able to exchange messages with each other. This opens up a real Pandora’s box. How will the networks manage keys, authenticate users, and moderate content? How much metadata will have to be shared, and how?

In our latest paper, One Protocol to Rule Them All? On Securing Interoperable Messaging, we explore the security tensions, the conflicts of interest, the usability traps, and the likely consequences for individual and institutional behaviour.

Interoperability will vastly increase the attack surface at every level in the stack – from the cryptography up through usability to commercial incentives and the opportunities for government interference.

Twenty-five years ago, we warned that key escrow mechanisms would endanger cryptography by increasing complexity, even if the escrow keys themselves can be kept perfectly secure. Interoperability is complexity on steroids.

A striking memoir by Gus Simmons

Authentication, News coverage, Politics

Gus Simmons is one of the pioneers of cryptography and computer security. His contributions to public-key cryptography, unconditional authentication, covert channels and information hiding earned him an honorary degree, fellowship of the IACR, and election to the Rothschild chair of mathematics when he visited us in Cambridge in 1996. And this was his hobby; his day job was a mathematician at Sandia National Laboratories, where he worked on satellite imagery, arms-control treaty verification, and the command and control of nuclear weapons.

During lockdown, Gus wrote a book of stories about growing up in West Virginia during the depression years of the 1930s. After he circulated it privately to a few friends in the cryptographic community, we persuaded him to put it online so everyone can read it. During this desolate time, coal mines closed and fired their workers, who took over abandoned farms and survived as best they could. Gus’s memoir is a gripping oral history of a period when some parts of the U.S.A. were just as poor as rural Africa today.

Here it is: Another Time, Another Place, Another Story.

WEIS 2020 – Liveblog

Authentication, Cybercrime, Legal issues, Politics, Security economics, Security psychology

I’ll be trying to liveblog the seventeenth Workshop on the Economics of Information Security (WEIS), which is being held online today and tomorrow (December 14/15) and streamed live on the CEPS channel on YouTube. The event was introduced by the general chair, Lorenzo Pupillo of CEPS, and the program chair Nicolas Christin of CMU. My summaries of the sessions will appear as followups to this post, and videos will be linked here in a few days.

Towards greater ecological validity in security usability

Academic papers, Authentication, Open-source security, Web security, ,

When you are a medical doctor, friends and family invariably ask you about their aches and pains. When you are a computer specialist, they ask you to fix their computer. About ten years ago, most of the questions I was getting from friends and family as a security techie had to do with frustration over passwords. I observed that what techies had done to the rest of humanity was not just wrong but fundamentally unethical: asking people to do something impossible and then, if they got hacked, blaming them for not doing it.



So in 2011, years before the Fido Alliance was formed (2013) and Apple announced its smartwatch (2014), I published my detailed design for a clean-slate password replacement I called Pico, an alternative system intended to be easier to use and more secure than passwords. The European Research Council was generous enough to fund my vision with a grant that allowed me to recruit and lead a team of brilliant researchers over a period of five years. We built a number of prototypes, wrote a bunch of papers, offered projects to a number of students and even launched a start-up and thereby learnt a few first-hand lessons about business, venture capital, markets, sales and the difficult process of transitioning from academic research to a profitable commercial product. During all those years we changed our minds a few times about what ought to be done and we came to understand a lot better both the problem space and the mindset of the users.

Continue reading Towards greater ecological validity in security usability →

Manifestos and tech

Authentication, Cybercrime, Internet censorship, Legal issues, News coverage, Politics, Security economics

The papers went to town yesterday on the Conservative manifesto but missed some interesting bits.

First, no-one seems to have noticed that the smart meter programme is being quietly put to death. We read on page 60 that everyone will be offered a smart meter by 2020. So a mandatory national programme has become voluntary, just like that. Regular readers of this blog will recall that the programme was sold in 2008 by Ed Milliband using a dishonest impact assessment, yet all the parties backed it after 2010, leaving no-one to point out that it was going to cost us all a fortune and never save any carbon. May says she wants to reduce energy costs; this was surely a no-brainer.

That was the good news for England. The good news for friends in rural Scotland is high-speed broadband for all by 2020. But there are some rather weird things in there too.

What on earth is “the right of businesses to insist on a digital signature”? Digital signatures are very 1998, and we already have the electronic signature directive. From whom will businesses be able to insist on a signature, and if I’m one of the legislated victims, how much do I have to pay to buy the apparatus?

All digital businesses will have “to support new digital proofs of identification”. That presumably means forcing firms to use Verify, a dysfunctional online authentication service whose roots lie in Blair’s obsession with identity. If a newspaper currently identifies its subscribers via a proprietary logon, will they have to offer Verify as an option? Will it have to be the only option, displacing Facebook and Twitter? The manifesto also says that local government will have to use Verify; and elsewhere that councils must publish planning applications and bus routes “without the hassle and delay that currently exists.” OK, so some councils could so with more competent webmasters, but don’t worry: “hundreds of leaders from the world of tech can come into government to help deliver better public services.”

The Land Registry, the Ordnance Survey and other quangos that do geography (our leader’s degree subject) will all band together to create the largest open repository of land data in the world. So where will the Ordnance Survey get its money from then? That small question killed the same idea in 2010 after Tim Berners-Lee sold it to Cameron.

There will be a levy on social media companies, like on gambling companies, to support awareness and preventive activity. And they must not direct users, even unintentionally, to hate speech. So will Facebook be fined whenever they let users like a xenophobic article in the Daily Mail?

No doubt in view of the delicacy of such regulatory decisions, Leveson II is killed; there will be a Data Use and Ethics Commission instead. It will advise regulators and develop the principles and rules that will give people confidence their data are being handled properly. Wow. We now have the Charter of Fundamental Rights to give us principles, the GDPR to give us rules, and the ECJ to hammer out the case law. Now the People don’t have confidence in such experts we’re going to let the Prime Minister of the day appoint a different lot.

The next government will further strengthen cyber security standards for government and public services, so presumably all such services will have to use expensive networks such as the NHS-wide network from BT which will expect them to manage their own firewalls without telling them how to.

But don’t worry. It will become “as difficult to commit a crime digitally as it is physically”. There is text about working “with international law enforcement agencies to ensure perpetrators are brought to justice” but our local police force isn’t allowed to do anything effective about online accommodation fraud committed by a gang in Germany. They have to work through the NCA – who don’t care. The manifesto signals more of the same: the NCA will get to eat the SFO, which does crimes over £100m, leaving them even less interested in online crooks who steal a thousand pounds of deposit from dozens of students a year.

In fact there is no signal anywhere in the manifesto that May understands the impact of volume cybercrime, even though it’s now most of the property crime in the UK. She rather prefers to boast of the falling crime over the past seven years, as if it were her achievement as Home Secretary. The simple fact is that crime has been going online like everything else, and until 2015 the online part of it wasn’t recorded properly. This was not the doing of Theresa May, but of Margaret Hodge.

The manifesto rather seems to have been drafted in a geek-free room. And let’s not spoil the party by mentioning the impact that tight immigration targets will have on the IT industry, or for that matter on higher education. Perhaps they want us to hope that they don’t really mean that part of it, but perhaps we’d better make a plan to open a campus in India or Canada, just in case.