Entries Tagged "essays"

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Impersonation

Impersonation isn’t new. In 1556, a Frenchman was executed for impersonating Martin Guerre and this week hackers impersonated Barack Obama on Twitter. It’s not even unique to humans: mockingbirds, Viceroy butterflies, and the mimic octopus all use impersonation as a survival strategy. For people, detecting impersonation is a hard problem for three reasons: we need to verify the identity of people we don’t know, we interact with people through “narrow” communications channels like the telephone and Internet, and we want computerized systems to do the verification for us.

Traditional impersonation involves people fooling people. It’s still done today: impersonating garbage men to collect tips, impersonating parking lot attendants to collect fees, or impersonating the French president to fool Sarah Palin. Impersonating people like policemen, security guards, and meter readers is a common criminal tactic.

These tricks work because we all regularly interact with people we don’t know. No one could successfully impersonate your brother, your best friend, or your boss, because you know them intimately. But a policeman or a parking lot attendant? That’s just someone with a badge or a uniform. But badges and ID cards only help if you know how to verify one. Do you know what a valid police ID looks like? Or how to tell a real telephone repairman’s badge from a forged one?

Still, it’s human nature to trust these credentials. We naturally trust uniforms, even though we know that anyone can wear one. When we visit a Web site, we use the professionalism of the page to judge whether or not it’s really legitimate—never mind that anyone can cut and paste graphics. Watch the next time someone other than law enforcement verifies your ID; most people barely look at it.

Impersonation is even easier over limited communications channels. On the telephone, how can you distinguish someone working at your credit card company from someone trying to steal your account details and login information? On e-mail, how can you distinguish someone from your company’s tech support from a hacker trying to break into your network—or the mayor of Paris from an impersonator? Once in a while someone frees himself from jail by faxing a forged release order to his warden. This is social engineering: impersonating someone convincingly enough to fool the victim.

These days, a lot of identity verification happens with computers. Computers are fast at computation but not very good at judgment, and can be tricked. So people can fool speed cameras by taping a fake license plate over the real one, fingerprint readers with a piece of tape, or automatic face scanners with—and I’m not making this up—a photograph of a face held in front of their own. Even the most bored policeman wouldn’t fall for any of those tricks.

This is why identity theft is such a big problem today. So much authentication happens online, with only a small amount of information: user ID, password, birth date, Social Security number, and so on. Anyone who gets that information can impersonate you to a computer, which doesn’t know any better.

Despite all of these problems, most authentication systems work most of the time. Even something as ridiculous as faxed signatures work, and can be legally binding. But no authentication system is perfect, and impersonation is always possible.

This lack of perfection is okay, though. Security is a trade-off, and any well-designed authentication system balances security with ease of use, customer acceptance, cost, and so on. More authentication isn’t always better. Banks make this trade-off when they don’t bother authenticating signatures on checks under amounts like $25,000; it’s cheaper to deal with fraud after the fact. Web sites make this trade-off when they use simple passwords instead of something more secure, and merchants make this trade-off when they don’t bother verifying your signature against your credit card. We make this trade-off when we accept police badges, Best Buy uniforms, and faxed signatures with only a cursory amount of verification.

Good authentication systems also balance false positives against false negatives. Impersonation is just one way these systems can fail; they can also fail to authenticate the real person. An ATM is better off allowing occasional fraud than preventing legitimate account holders access to their money. On the other hand, a false positive in a nuclear launch system is much more dangerous; better to not launch the missiles.

Decentralized authentication systems work better than centralized ones. Open your wallet, and you’ll see a variety of physical tokens used to identify you to different people and organizations: your bank, your credit card company, the library, your health club, and your employer, as well as a catch-all driver’s license used to identify you in a variety of circumstances. That assortment is actually more secure than a single centralized identity card: each system must be broken individually, and breaking one doesn’t give the attacker access to everything. This is one of the reasons that centralized systems like REAL-ID make us less secure.

Finally, any good authentication system uses defense in depth. Since no authentication system is perfect, there need to be other security measures in place if authentication fails. That’s why all of a corporation’s assets and information isn’t available to anyone who can bluff his way into the corporate offices. That is why credit card companies have expert systems analyzing suspicious spending patterns. And it’s why identity theft won’t be solved by making personal information harder to steal.

We can reduce the risk of impersonation, but it will always be with us; technology cannot “solve” it in any absolute sense. Like any security, the trick is to balance the trade-offs. Too little security, and criminals withdraw money from all our bank accounts. Too much security and when Barack Obama calls to congratulate you on your reelection, you won’t believe it’s him.

This essay originally appeared in The Wall Street Journal.

Posted on January 9, 2009 at 2:04 PM • View Comments

Biometrics

Biometrics may seem new, but they’re the oldest form of identification. Tigers recognize each other’s scent; penguins recognize calls. Humans recognize each other by sight from across the room, voices on the phone, signatures on contracts and photographs on driver’s licenses. Fingerprints have been used to identify people at crime scenes for more than 100 years.

What is new about biometrics is that computers are now doing the recognizing: thumbprints, retinal scans, voiceprints, and typing patterns. There’s a lot of technology involved here, in trying to both limit the number of false positives (someone else being mistakenly recognized as you) and false negatives (you being mistakenly not recognized). Generally, a system can choose to have less of one or the other; less of both is very hard.

Biometrics can vastly improve security, especially when paired with another form of authentication such as passwords. But it’s important to understand their limitations as well as their strengths. On the strength side, biometrics are hard to forge. It’s hard to affix a fake fingerprint to your finger or make your retina look like someone else’s. Some people can mimic voices, and make-up artists can change people’s faces, but these are specialized skills.

On the other hand, biometrics are easy to steal. You leave your fingerprints everywhere you touch, your iris scan everywhere you look. Regularly, hackers have copied the prints of officials from objects they’ve touched, and posted them on the Internet. We haven’t yet had an example of a large biometric database being hacked into, but the possibility is there. Biometrics are unique identifiers, but they’re not secrets.

And a stolen biometric can fool some systems. It can be as easy as cutting out a signature, pasting it onto a contract, and then faxing the page to someone. The person on the other end doesn’t know that the signature isn’t valid because he didn’t see it fixed onto the page. Remote logins by fingerprint fail in the same way. If there’s no way to verify the print came from an actual reader, not from a stored computer file, the system is much less secure.

A more secure system is to use a fingerprint to unlock your mobile phone or computer. Because there is a trusted path from the fingerprint reader to the stored fingerprint the system uses to compare, an attacker can’t inject a previously stored print as easily as he can cut and paste a signature. A photo on an ID card works the same way: the verifier can compare the face in front of him with the face on the card.

Fingerprints on ID cards are more problematic, because the attacker can try to fool the fingerprint reader. Researchers have made false fingers out of rubber or glycerin. Manufacturers have responded by building readers that also detect pores or a pulse.

The lesson is that biometrics work best if the system can verify that the biometric came from the person at the time of verification. The biometric identification system at the gates of the CIA headquarters works because there’s a guard with a large gun making sure no one is trying to fool the system.

Of course, not all systems need that level of security. At Counterpane, the security company I founded, we installed hand geometry readers at the access doors to the operations center. Hand geometry is a hard biometric to copy, and the system was closed and didn’t allow electronic forgeries. It worked very well.

One more problem with biometrics: they don’t fail well. Passwords can be changed, but if someone copies your thumbprint, you’re out of luck: you can’t update your thumb. Passwords can be backed up, but if you alter your thumbprint in an accident, you’re stuck. The failures don’t have to be this spectacular: a voiceprint reader might not recognize someone with a sore throat, or a fingerprint reader might fail outside in freezing weather. Biometric systems need to be analyzed in light of these possibilities.

Biometrics are easy, convenient, and when used properly, very secure; they’re just not a panacea. Understanding how they work and fail is critical to understanding when they improve security and when they don’t.

This essay originally appeared in the Guardian, and is an update of an essay I wrote in 1998.

Posted on January 8, 2009 at 12:53 PM • View Comments

Audit

As the first digital president, Barack Obama is learning the hard way how difficult it can be to maintain privacy in the information age. Earlier this year, his passport file was snooped by contract workers in the State Department. In October, someone at Immigration and Customs Enforcement leaked information about his aunt’s immigration status. And in November, Verizon employees peeked at his cell phone records.

What these three incidents illustrate is not that computerized databases are vulnerable to hacking—we already knew that, and anyway the perpetrators all had legitimate access to the systems they used—but how important audit is as a security measure.

When we think about security, we commonly think about preventive measures: locks to keep burglars out of our homes, bank safes to keep thieves from our money, and airport screeners to keep guns and bombs off airplanes. We might also think of detection and response measures: alarms that go off when burglars pick our locks or dynamite open bank safes, sky marshals on airplanes who respond when a hijacker manages to sneak a gun through airport security. But audit, figuring out who did what after the fact, is often far more important than any of those other three.

Most security against crime comes from audit. Of course we use locks and alarms, but we don’t wear bulletproof vests. The police provide for our safety by investigating crimes after the fact and prosecuting the guilty: that’s audit.

Audit helps ensure that people don’t abuse positions of trust. The cash register, for example, is basically an audit system. Cashiers have to handle the store’s money. To ensure they don’t skim from the till, the cash register keeps an audit trail of every transaction. The store owner can look at the register totals at the end of the day and make sure the amount of money in the register is the amount that should be there.

The same idea secures us from police abuse, too. The police have enormous power, including the ability to intrude into very intimate aspects of our life in order to solve crimes and keep the peace. This is generally a good thing, but to ensure that the police don’t abuse this power, we put in place systems of audit like the warrant process.

The whole NSA warrantless eavesdropping scandal was about this. Some misleadingly painted it as allowing the government to eavesdrop on foreign terrorists, but the government always had that authority. What the government wanted was to not have to submit a warrant, even after the fact, to a secret FISA court. What they wanted was to not be subject to audit.

That would be an incredibly bad idea. Law enforcement systems that don’t have good audit features designed in, or are exempt from this sort of audit-based oversight, are much more prone to abuse by those in power—because they can abuse the system without the risk of getting caught. Audit is essential as the NSA increases its domestic spying. And large police databases, like the FBI Next Generation Identification System, need to have strong audit features built in.

For computerized database systems like that—systems entrusted with other people’s information—audit is a very important security mechanism. Hospitals need to keep databases of very personal health information, and doctors and nurses need to be able to access that information quickly and easily. A good audit record of who accessed what when is the best way to ensure that those trusted with our medical information don’t abuse that trust. It’s the same with IRS records, credit reports, police databases, telephone records – anything personal that someone might want to peek at during the course of his job.

Which brings us back to President Obama. In each of those three examples, someone in a position of trust inappropriately accessed personal information. The difference between how they played out is due to differences in audit. The State Department’s audit worked best; they had alarm systems in place that alerted superiors when Obama’s passport files were accessed and who accessed them. Verizon’s audit mechanisms worked less well; they discovered the inappropriate account access and have narrowed the culprits down to a few people. Audit at Immigration and Customs Enforcement was far less effective; they still don’t know who accessed the information.

Large databases filled with personal information, whether managed by governments or corporations, are an essential aspect of the information age. And they each need to be accessed, for legitimate purposes, by thousands or tens of thousands of people. The only way to ensure those people don’t abuse the power they’re entrusted with is through audit. Without it, we will simply never know who’s peeking at what.

This essay first appeared on the Wall Street Journal website.

Posted on December 10, 2008 at 2:21 PM • View Comments

Here Comes Everybody Review

In 1937, Ronald Coase answered one of the most perplexing questions in economics: if markets are so great, why do organizations exist? Why don’t people just buy and sell their own services in a market instead? Coase, who won the 1991 Nobel Prize in Economics, answered the question by noting a market’s transaction costs: buyers and sellers need to find one another, then reach agreement, and so on. The Coase theorem implies that if these transaction costs are low enough, direct markets of individuals make a whole lot of sense. But if they are too high, it makes more sense to get the job done by an organization that hires people.

Economists have long understood the corollary concept of Coase’s ceiling, a point above which organizations collapse under their own weight—where hiring someone, however competent, means more work for everyone else than the new hire contributes. Software projects often bump their heads against Coase’s ceiling: recall Frederick P. Brooks Jr.’s seminal study, The Mythical Man-Month (Addison-Wesley, 1975), which showed how adding another person onto a project can slow progress and increase errors.

What’s new is something consultant and social technologist Clay Shirky calls "Coase’s Floor," below which we find projects and activities that aren’t worth their organizational costs—things so esoteric, so frivolous, so nonsensical, or just so thoroughly unimportant that no organization, large or small, would ever bother with them. Things that you shake your head at when you see them and think, "That’s ridiculous."

Sounds a lot like the Internet, doesn’t it? And that’s precisely Shirky’s point. His new book, Here Comes Everybody: The Power of Organizing Without Organizations, explores a world where organizational costs are close to zero and where ad hoc, loosely connected groups of unpaid amateurs can create an encyclopedia larger than the Britannica and a computer operating system to challenge Microsoft’s.

Shirky teaches at New York University’s Interactive Telecommunications Program, but this is no academic book. Sacrificing rigor for readability, Here Comes Everybody is an entertaining as well as informative romp through some of the Internet’s signal moments—the Howard Dean phenomenon, Belarusian protests organized on LiveJournal, the lost cellphone of a woman named Ivanna, Meetup.com, flash mobs, Twitter, and more—which Shirky uses to illustrate his points.

The book is filled with bits of insight and common sense, explaining why young people take better advantage of social tools, how the Internet affects social change, and how most Internet discourse falls somewhere between dinnertime conversation and publishing.

Shirky notes that "most user-generated content isn’t ‘content’ at all, in the sense of being created for general consumption, any more than a phone call between you and a sibling is ‘family-generated content.’ Most of what gets created on any given day is just the ordinary stuff of life—gossip, little updates, thinking out loud—but now it’s done in the same medium as professionally produced material. Unlike professionally produced material, however, Internet content can be organized after the fact."

No one coordinates Flickr’s 6 million to 8 million users. Yet Flickr had the first photos from the 2005 London Transport bombings, beating the traditional news media. Why? People with cellphone cameras uploaded their photos to Flickr. They coordinated themselves using tools that Flickr provides. This is the sort of impromptu organization the Internet is ideally suited for. Shirky explains how these moments are harbingers of a future that can self-organize without formal hierarchies.

These nonorganizations allow for contributions from a wider group of people. A newspaper has to pay someone to take photos; it can’t be bothered to hire someone to stand around London underground stations waiting for a major event. Similarly, Microsoft has to pay a programmer full time, and Encyclopedia Britannica has to pay someone to write articles. But Flickr can make use of a person with just one photo to contribute, Linux can harness the work of a programmer with little time, and Wikipedia benefits if someone corrects just a single typo. These aggregations of millions of actions that were previously below the Coasean floor have enormous potential.

But a flash mob is still a mob. In a world where the Coasean floor is at ground level, all sorts of organizations appear, including ones you might not like: violent political organizations, hate groups, Holocaust deniers, and so on. (Shirky’s discussion of teen anorexia support groups makes for very disturbing reading.) This has considerable implications for security, both online and off.

We never realized how much our security could be attributed to distance and inconvenience—how difficult it is to recruit, organize, coordinate, and communicate without formal organizations. That inadvertent measure of security is now gone. Bad guys, from hacker groups to terrorist groups, will use the same ad hoc organizational technologies that the rest of us do. And while there has been some success in closing down individual Web pages, discussion groups, and blogs, these are just stopgap measures.

In the end, a virtual community is still a community, and it needs to be treated as such. And just as the best way to keep a neighborhood safe is for a policeman to walk around it, the best way to keep a virtual community safe is to have a virtual police presence.

Crime isn’t the only danger; there is also isolation. If people can segregate themselves in ever-increasingly specialized groups, then they’re less likely to be exposed to alternative ideas. We see a mild form of this in the current political trend of rival political parties having their own news sources, their own narratives, and their own facts. Increased radicalization is another danger lurking below the Coasean floor.

There’s no going back, though. We’ve all figured out that the Internet makes freedom of speech a much harder right to take away. As Shirky demonstrates, Web 2.0 is having the same effect on freedom of assembly. The consequences of this won’t be fully seen for years.

Here Comes Everybody covers some of the same ground as Yochai Benkler’s Wealth of Networks. But when I had to explain to one of my corporate attorneys how the Internet has changed the nature of public discourse, Shirky’s book is the one I recommended.

This essay previously appeared in IEEE Spectrum.

EDITED TO ADD (12/13): Interesting Clay Shirky podcast.

Posted on November 25, 2008 at 7:39 AM • View Comments

The Future of Ephemeral Conversation

When he becomes president, Barack Obama will have to give up his BlackBerry. Aides are concerned that his unofficial conversations would become part of the presidential record, subject to subpoena and eventually made public as part of the country’s historical record.

This reality of the information age might be particularly stark for the president, but it’s no less true for all of us. Conversation used to be ephemeral. Whether face-to-face or by phone, we could be reasonably sure that what we said disappeared as soon as we said it. Organized crime bosses worried about phone taps and room bugs, but that was the exception. Privacy was just assumed.

This has changed. We chat in e-mail, over SMS and IM, and on social networking websites like Facebook, MySpace, and LiveJournal. We blog and we Twitter. These conversations—with friends, lovers, colleagues, members of our cabinet—are not ephemeral; they leave their own electronic trails.

We know this intellectually, but we haven’t truly internalized it. We type on, engrossed in conversation, forgetting we’re being recorded and those recordings might come back to haunt us later.

Oliver North learned this, way back in 1987, when messages he thought he had deleted were saved by the White House PROFS system, and then subpoenaed in the Iran-Contra affair. Bill Gates learned this in 1998 when his conversational e-mails were provided to opposing counsel as part of the antitrust litigation discovery process. Mark Foley learned this in 2006 when his instant messages were saved and made public by the underage men he talked to. Paris Hilton learned this in 2005 when her cell phone account was hacked, and Sarah Palin learned it earlier this year when her Yahoo e-mail account was hacked. Someone in George W. Bush’s administration learned this, and millions of e-mails went mysteriously and conveniently missing.

Ephemeral conversation is dying.

Cardinal Richelieu famously said, :If one would give me six lines written by the hand of the most honest man, I would find something in them to have him hanged.” When all our ephemeral conversations can be saved for later examination, different rules have to apply. Conversation is not the same thing as correspondence. Words uttered in haste over morning coffee, whether spoken in a coffee shop or thumbed on a Blackberry, are not official pronouncements. Discussions in a meeting, whether held in a boardroom or a chat room, are not the same as answers at a press conference. And privacy isn’t just about having something to hide; it has enormous value to democracy, liberty, and our basic humanity.

We can’t turn back technology; electronic communications are here to stay and even our voice conversations are threatened. But as technology makes our conversations less ephemeral, we need laws to step in and safeguard ephemeral conversation. We need a comprehensive data privacy law, protecting our data and communications regardless of where it is stored or how it is processed. We need laws forcing companies to keep it private and delete it as soon as it is no longer needed. Laws requiring ISPs to store e-mails and other personal communications are exactly what we don’t need.

Rules pertaining to government need to be different, because of the power differential. Subjecting the president’s communications to eventual public review increases liberty because it reduces the government’s power with respect to the people. Subjecting our communications to government review decreases liberty because it reduces our power with respect to the government. The president, as well as other members of government, need some ability to converse ephemerally—just as they’re allowed to have unrecorded meetings and phone calls—but more of their actions need to be subject to public scrutiny.

But laws can only go so far. Law or no law, when something is made public it’s too late. And many of us like having complete records of all our e-mail at our fingertips; it’s like our offline brains.

In the end, this is cultural.

The Internet is the greatest generation gap since rock and roll. We’re now witnessing one aspect of that generation gap: the younger generation chats digitally, and the older generation treats those chats as written correspondence. Until our CEOs blog, our Congressmen Twitter, and our world leaders send each other LOLcats – until we have a Presidential election where both candidates have a complete history on social networking sites from before they were teenagers– we aren’t fully an information age society.

When everyone leaves a public digital trail of their personal thoughts since birth, no one will think twice about it being there. Obama might be on the younger side of the generation gap, but the rules he’s operating under were written by the older side. It will take another generation before society’s tolerance for digital ephemera changes.

This essay previously appeared on The Wall Street Journal website (not the print newspaper), and is an update of something I wrote previously.

Posted on November 24, 2008 at 2:06 PM • View Comments

Skein and SHA-3 News

There are two bugs in the Skein code. They are subtle and esoteric, but they’re there. We have revised both the reference and optimized code—and provided new test vectors—on the Skein website. A revision of the paper—Version 1.1—has new IVs, new test vectors, and also fixes a few typos in the paper.

Errata: Version 1.1 of the paper, reference, and optimized code corrects an error in which the length of the configuration string was passed in as the size of the internal block (256 bits for Skein-256, 512 for Skein-512, and 1024 for Skein-1024), instead of a constant 256 bits for all three sizes. This error has no cryptographic significance, but affected the test vectors and the initialization values. The revised code also fixes a bug in the MAC mode key processing. This bug does not affect the NIST submission in any way.

NIST has received 64 submissions. (This article interviews one of the submitters, who is fifteen.) Of those, 28 are public and six have been broken. NIST is going through the submissions right now, making sure they are complete and proper. Their goal is to publish the accepted submissions by the end of the month, in advance of the Third Cryptographic Hash Workshop to be held in Belgium right after FSE in February. They expect to quickly make a first cut of algorithms—hopefully to about a dozen—and then give the community about a year of cryptanalysis before making a second cut in 2010.

Lastly, this is a really nice article on Skein.

These submissions make some accommodation to the Core 2 processor. They operate in “little-endian” mode (a quirk of the Intel-like processors that reads some bytes in reverse order). They also allow a large file to be broken into chunks to split the work across multiple processors.

However, virtually all of the contest submissions share the performance problem mentioned above. The logic they use won’t optimally fit within the constraints of a Intel Core 2 processor. Most will perform as bad or worse than the existing SHA-1 algorithm.

One exception to this is Skein, created by several well-known cryptographers and noted pundit Bruce Schneier. It was designed specifically to exploit all three of the Core 2 execution units and to run at a full 64-bits. This gives it roughly four to 10 times the logic density of competing submissions.

This is what I meant by the Matrix quote above. They didn’t bend the spoon; they bent the crypto algorithm. They moved the logic operations around in a way that wouldn’t weaken the crypto, but would strengthen its speed on the Intel Core 2.

In their paper (PDF), the authors of Skein express surprise that a custom silicon ASIC implementation is not any faster than the software implementation. They shouldn’t be surprised. Every time you can redefine a problem to run optimally in software, you will reach the same speeds you get with optimized ASIC hardware. The reason software has a reputation of being slow is because people don’t redefine the original problem.

That’s exactly what we were trying to do.

EDITED TO ADD (11/20): I wrote an essay for Wired.com on the process.

Posted on November 19, 2008 at 6:14 AM • View Comments

Quantum Cryptography

Quantum cryptography is back in the news, and the basic idea is still unbelievably cool, in theory, and nearly useless in real life.

The idea behind quantum crypto is that two people communicating using a quantum channel can be absolutely sure no one is eavesdropping. Heisenberg’s uncertainty principle requires anyone measuring a quantum system to disturb it, and that disturbance alerts legitimate users as to the eavesdropper’s presence. No disturbance, no eavesdropper—period.

This month we’ve seen reports on a new working quantum-key distribution network in Vienna, and a new quantum-key distribution technique out of Britain. Great stuff, but headlines like the BBC’s “‘Unbreakable’ encryption unveiled” are a bit much.

The basic science behind quantum crypto was developed, and prototypes built, in the early 1980s by Charles Bennett and Giles Brassard, and there have been steady advances in engineering since then. I describe basically how it all works in Applied Cryptography, 2nd Edition (pages 554-557). At least one company already sells quantum-key distribution products.

Note that this is totally separate from quantum computing, which also has implications for cryptography. Several groups are working on designing and building a quantum computer, which is fundamentally different from a classical computer. If one were built—and we’re talking science fiction here—then it could factor numbers and solve discrete-logarithm problems very quickly. In other words, it could break all of our commonly used public-key algorithms. For symmetric cryptography it’s not that dire: A quantum computer would effectively halve the key length, so that a 256-bit key would be only as secure as a 128-bit key today. Pretty serious stuff, but years away from being practical. I think the best quantum computer today can factor the number 15.

While I like the science of quantum cryptography—my undergraduate degree was in physics—I don’t see any commercial value in it. I don’t believe it solves any security problem that needs solving. I don’t believe that it’s worth paying for, and I can’t imagine anyone but a few technophiles buying and deploying it. Systems that use it don’t magically become unbreakable, because the quantum part doesn’t address the weak points of the system.

Security is a chain; it’s as strong as the weakest link. Mathematical cryptography, as bad as it sometimes is, is the strongest link in most security chains. Our symmetric and public-key algorithms are pretty good, even though they’re not based on much rigorous mathematical theory. The real problems are elsewhere: computer security, network security, user interface and so on.

Cryptography is the one area of security that we can get right. We already have good encryption algorithms, good authentication algorithms and good key-agreement protocols. Maybe quantum cryptography can make that link stronger, but why would anyone bother? There are far more serious security problems to worry about, and it makes much more sense to spend effort securing those.

As I’ve often said, it’s like defending yourself against an approaching attacker by putting a huge stake in the ground. It’s useless to argue about whether the stake should be 50 feet tall or 100 feet tall, because either way, the attacker is going to go around it. Even quantum cryptography doesn’t “solve” all of cryptography: The keys are exchanged with photons, but a conventional mathematical algorithm takes over for the actual encryption.

I’m always in favor of security research, and I have enjoyed following the developments in quantum cryptography. But as a product, it has no future. It’s not that quantum cryptography might be insecure; it’s that cryptography is already sufficiently secure.

This essay previously appeared on Wired.com.

EDITED TO ADD (10/21): It’s amazing; even reporters responding to my essay get it completely wrong:

Keith Harrison, a cryptographer with HP Laboratories, is quoted by the Telegraph as saying that, as quantum computing becomes commonplace, hackers will use the technology to crack conventional encryption.

“We have to be thinking about solutions to the problems that quantum computing will pose,” he told the Telegraph. “The average consumer is going to want to know their own transactions and daily business is secure.

“One way of doing this is to use a one time pad essentially lists of random numbers where one copy of the numbers is held by the person sending the information and an identical copy is held by the person receiving the information. These are completely unbreakable when used properly,” he explained.

The critical feature of quantum computing is the unique fact that, if someone tampers with an information feed between two parties, then the nature of the quantum feed changes.

This makes eavesdropping impossible.

No, it wouldn’t make eavesdropping impossible. It would make eavesdropping on the communications channel impossible unless someone made an implementation error. (In the 80s, the NSA broke Soviet one-time-pad systems because the Soviets reused the pad.) Eavesdropping via spyware or Trojan or TEMPEST would still be possible.

EDITED TO ADD (10/26): Here’s another commenter who gets it wrong:

Now let me get this straight: I have no doubt that there are many greater worries in security than “mathematical crypography.” But does this justify totally ignoring the possibility that a cryptographic system might possibly be breakable? I mean maybe I’m influenced by this in the fact that I’ve been sitting in on a cryptanalysis course and I just met a graduate student who broke a cryptographic pseudorandom number generator, but really what kind of an argument is this? “Um, well, sometimes our cryptographic systems have been broken, but that’s nothing to worry about, because, you know, everything is kosher with the systems we are using.”

The point isn’t to ignore the possibility that a cryptographic system might possibly be broken; the point is to pay attention to the other parts of the system that are much much more likely to be already broken. Security is a chain; it’s only as secure as the weakest link. The cryptographic systems, as potentially flawed as they are, are the strongest link in the chain. We’d get a lot more security devoting our resources to making all those weaker links more secure.

Again, this is not to say that quantum cryptography isn’t incredibly cool research. It is, and I hope it continues to receive all sorts of funding. But for an operational network that is worried about security: you’ve got much bigger worries than whether Diffie-Hellman will be broken someday.

Posted on October 21, 2008 at 6:48 AM • View Comments

Does Risk Management Make Sense?

We engage in risk management all the time, but it only makes sense if we do it right.

“Risk management” is just a fancy term for the cost-benefit tradeoff associated with any security decision. It’s what we do when we react to fear, or try to make ourselves feel secure. It’s the fight-or-flight reflex that evolved in primitive fish and remains in all vertebrates. It’s instinctual, intuitive and fundamental to life, and one of the brain’s primary functions.

Some have hypothesized that humans have a “risk thermostat” that tries to maintain some optimal risk level. It explains why we drive our motorcycles faster when we wear a helmet, or are more likely to take up smoking during wartime. It’s our natural risk management in action.

The problem is our brains are intuitively suited to the sorts of risk management decisions endemic to living in small family groups in the East African highlands in 100,000 BC, and not to living in the New York City of 2008. We make systematic risk management mistakes—miscalculating the probability of rare events, reacting more to stories than data, responding to the feeling of security rather than reality, and making decisions based on irrelevant context. And that risk thermostat of ours? It’s not nearly as finely tuned as we might like it to be.

Like a rabbit that responds to an oncoming car with its default predator avoidance behavior—dart left, dart right, dart left, and at the last moment jump—instead of just getting out of the way, our Stone Age intuition doesn’t serve us well in a modern technological society. So when we in the security industry use the term “risk management,” we don’t want you to do it by trusting your gut. We want you to do risk management consciously and intelligently, to analyze the tradeoff and make the best decision.

This means balancing the costs and benefits of any security decision—buying and installing a new technology, implementing a new procedure or forgoing a common precaution. It means allocating a security budget to mitigate different risks by different amounts. It means buying insurance to transfer some risks to others. It’s what businesses do, all the time, about everything. IT security has its own risk management decisions, based on the threats and the technologies.

There’s never just one risk, of course, and bad risk management decisions often carry an underlying tradeoff. Terrorism policy in the U.S. is based more on politics than actual security risk, but the politicians who make these decisions are concerned about the risks of not being re-elected.

Many corporate security decisions are made to mitigate the risk of lawsuits rather than address the risk of any actual security breach. And individuals make risk management decisions that consider not only the risks to the corporation, but the risks to their departments’ budgets, and to their careers.

You can’t completely remove emotion from risk management decisions, but the best way to keep risk management focused on the data is to formalize the methodology. That’s what companies that manage risk for a living—insurance companies, financial trading firms and arbitrageurs—try to do. They try to replace intuition with models, and hunches with mathematics.

The problem in the security world is we often lack the data to do risk management well. Technological risks are complicated and subtle. We don’t know how well our network security will keep the bad guys out, and we don’t know the cost to the company if we don’t keep them out. And the risks change all the time, making the calculations even harder. But this doesn’t mean we shouldn’t try.

You can’t avoid risk management; it’s fundamental to business just as to life. The question is whether you’re going to try to use data or whether you’re going to just react based on emotions, hunches and anecdotes.

This essay appeared as the first half of a point-counterpoint with Marcus Ranum in Information Security magazine.

Posted on October 14, 2008 at 1:25 PM • View Comments

The Seven Habits of Highly Ineffective Terrorists

Most counterterrorism policies fail, not because of tactical problems, but because of a fundamental misunderstanding of what motivates terrorists in the first place. If we’re ever going to defeat terrorism, we need to understand what drives people to become terrorists in the first place.

Conventional wisdom holds that terrorism is inherently political, and that people become terrorists for political reasons. This is the “strategic” model of terrorism, and it’s basically an economic model. It posits that people resort to terrorism when they believe—rightly or wrongly—that terrorism is worth it; that is, when they believe the political gains of terrorism minus the political costs are greater than if they engaged in some other, more peaceful form of protest. It’s assumed, for example, that people join Hamas to achieve a Palestinian state; that people join the PKK to attain a Kurdish national homeland; and that people join al-Qaida to, among other things, get the United States out of the Persian Gulf.

If you believe this model, the way to fight terrorism is to change that equation, and that’s what most experts advocate. Governments tend to minimize the political gains of terrorism through a no-concessions policy; the international community tends to recommend reducing the political grievances of terrorists via appeasement, in hopes of getting them to renounce violence. Both advocate policies to provide effective nonviolent alternatives, like free elections.

Historically, none of these solutions has worked with any regularity. Max Abrahms, a predoctoral fellow at Stanford University’s Center for International Security and Cooperation, has studied dozens of terrorist groups from all over the world. He argues that the model is wrong. In a paper published this year in International Security that—sadly—doesn’t have the title “Seven Habits of Highly Ineffective Terrorists,” he discusses, well, seven habits of highly ineffective terrorists. These seven tendencies are seen in terrorist organizations all over the world, and they directly contradict the theory that terrorists are political maximizers:

Terrorists, he writes, (1) attack civilians, a policy that has a lousy track record of convincing those civilians to give the terrorists what they want; (2) treat terrorism as a first resort, not a last resort, failing to embrace nonviolent alternatives like elections; (3) don’t compromise with their target country, even when those compromises are in their best interest politically; (4) have protean political platforms, which regularly, and sometimes radically, change; (5) often engage in anonymous attacks, which precludes the target countries making political concessions to them; (6) regularly attack other terrorist groups with the same political platform; and (7) resist disbanding, even when they consistently fail to achieve their political objectives or when their stated political objectives have been achieved.

Abrahms has an alternative model to explain all this: People turn to terrorism for social solidarity. He theorizes that people join terrorist organizations worldwide in order to be part of a community, much like the reason inner-city youths join gangs in the United States.

The evidence supports this. Individual terrorists often have no prior involvement with a group’s political agenda, and often join multiple terrorist groups with incompatible platforms. Individuals who join terrorist groups are frequently not oppressed in any way, and often can’t describe the political goals of their organizations. People who join terrorist groups most often have friends or relatives who are members of the group, and the great majority of terrorist are socially isolated: unmarried young men or widowed women who weren’t working prior to joining. These things are true for members of terrorist groups as diverse as the IRA and al-Qaida.

For example, several of the 9/11 hijackers planned to fight in Chechnya, but they didn’t have the right paperwork so they attacked America instead. The mujahedeen had no idea whom they would attack after the Soviets withdrew from Afghanistan, so they sat around until they came up with a new enemy: America. Pakistani terrorists regularly defect to another terrorist group with a totally different political platform. Many new al-Qaida members say, unconvincingly, that they decided to become a jihadist after reading an extreme, anti-American blog, or after converting to Islam, sometimes just a few weeks before. These people know little about politics or Islam, and they frankly don’t even seem to care much about learning more. The blogs they turn to don’t have a lot of substance in these areas, even though more informative blogs do exist.

All of this explains the seven habits. It’s not that they’re ineffective; it’s that they have a different goal. They might not be effective politically, but they are effective socially: They all help preserve the group’s existence and cohesion.

This kind of analysis isn’t just theoretical; it has practical implications for counterterrorism. Not only can we now better understand who is likely to become a terrorist, we can engage in strategies specifically designed to weaken the social bonds within terrorist organizations. Driving a wedge between group members—commuting prison sentences in exchange for actionable intelligence, planting more double agents within terrorist groups—will go a long way to weakening the social bonds within those groups.

We also need to pay more attention to the socially marginalized than to the politically downtrodden, like unassimilated communities in Western countries. We need to support vibrant, benign communities and organizations as alternative ways for potential terrorists to get the social cohesion they need. And finally, we need to minimize collateral damage in our counterterrorism operations, as well as clamping down on bigotry and hate crimes, which just creates more dislocation and social isolation, and the inevitable calls for revenge.

This essay previously appeared on Wired.com.

EDITED TO ADD (10/9): Interesting rebuttal.

Posted on October 7, 2008 at 5:48 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.