Category: Digital Identity

Personal data on 2.9 million people goes missing

Joris Evers at CNet has done a nice wrap-up on the latest identity catastrophy.  (Plumes of smoke were seen coming from the reactor, but so far, there has been no proof of radioactive particles leaking into the environment): 

A CD containing personal information on Georgia residents has gone missing, according to the Georgia Department of Community The CD was lost by Affiliated Computer Services, a Dallas company handling claims for the health care programs, the statement said. The disc holds information on 2.9 million Georgia residents, said Lisa Marie Shekell, a Department of Community Health representative.

It is unclear if the data on the disc, which was lost in transit some time after March 22, was protected. However, it doesn't appear the data has been used fraudulently. “At this time, we do not have any indication that the information on the disk has been misused,” Shekell said.

In response to the loss, the Georgia Department of Community Health has asked ACS to notify all affected members in writing and supply them with information on credit watch monitoring as well as tips on how to obtain a free credit report, it said.  [Funny – I get junk mail with this offer every few days – Kim] 

There has been a string of data breaches in recent years, many of which were reported publicly because of new disclosure laws. About 40,000 Chicago Public Schools employees are at risk of identity fraud after two laptops containing their personal information were stolen Friday.

Last week, the University of California at San Francisco said a possible computer security breach may have exposed records of 46,000 campus and medical center faculty, staff and students.

Since early 2005, more than 150 million personal records have been exposed in dozens of incidents, according to information compiled by the Privacy Rights Clearinghouse.

Identity fraud continues to top the complaints reported to the Federal Trade Commission. Such complaints, which include credit card fraud, bank fraud, as well as phone and utilities fraud, accounted for 36 percent of the total 674,354 complaints submitted to the FTC and its external data contributors in 2006.

Beijing's new Internet identity system

According to the Financial Times, the Chinese government has clear digital identity ideas of its own. 

It's a simple solution, really.  Just make sure the government knows who everyone is and what they are doing all the time while they use the internet.  This applies as much to your identity as an “elf” as to your identity as a professional. 

Under a “real name verification system” to crack down on internet usage – and prevent internet addiction among the young – Chinese police are to check the identity card numbers of all would-be players of internet games.

While it is unclear how rigorously the system will be enforced, Monday’s move highlights Beijing’s desire to more closely regulate the internet and reduce the potential for anonymity…

The same crack down will help ensure Chinese bloggers aren't inconvenienced with the kinds of vexing issues we've faced here with the Sierra affair.

Chinese leaders recently announced a broad push to “purify” the internet of socially and politically suspect activity, and have been keen to push users to use their true identities online. Beijing is also looking at ways of implementing a “real name” system for bloggers to curb “irresponsible” commentary and intellectual property abuse.

It might sound a bit draconian to our ears, but Hu Qiheng of the China Internet Association said bloggers’ real names would be kept private “as long as they do no harm to the public interest”.  That's clearly benevolent, isn't it?  We all know what the public interest is.

According to FT: 

China’s 18-digit ID numbers are mainly based on place of birth, age and gender and are unique to each citizen, but widely available software can generate fake but plausible numbers.

Under the new system, Chinese police would check each number, a government official, Kou Xiaowei, said on Monday.

Players whose IDs showed they were under 18, or who submitted incorrect numbers, would be forced to play versions of online games featuring an anti-addiction system that encourages them to spend less time online, he said.

Minors who stayed online for more than three hours a day would have half of their game credits cancelled; those who played for more than five hours a day would have all of their credits taken away.

As far as I know, the proposal that age verification be used to combat addiction is entirely original (patented?)  The analysis of how this proposal stacks up against the Laws of Identity is left as an exercise for the reader.

More here…

Digital identity allows us to manage risk – not prove negatives

Jon's piece channeled below,  Steven O'Grady‘s comments at RedMonk and  Tim O’Reilly’s Blogger's Code of Conduct  all say important things about the horrifying Kathy Sierra situation.   I agree with everyone that reputation is important, just as it is in the physical world.  But I have a fair bit of trouble with some of the technical thinking involved.

I agree we should be responsible for everything that appears on our sites over which we have control.    And I agree that we should take all reasonable steps to ensure we control our systems as effectively as we can.  But I think it is important for everyone to understand that our starting point must be that every system can be breached.  Without such a point of departure, we will see further proliferation of Pollyannish systems that, as likely as not, end in regret.

Once you understand the possibility of breach, you can calculate the associated risks, and build the technology that has the greatest chance of being safe.  You can't do this if you don't understand the risks.  In this sense, all you can do is manage your risk.

When I first set up my blog to accept Information Cards, it prompted a number of people to try their hand at breaking in.  They were unable to compromise the InfoCard system, but guess what?  There was a security flaw in WordPress 2.0.1 that was exploited to post something in my name . 

By what logic was I responsible for it?  Because I chose to use WordPress – along with the other 900,000 people who had downloaded it and were thus open to this vulnerability?

I guess, by this logic, I would also be responsible for any issues related to problems in the linux kernel operating underneath my blog; and for  potential bugs in MySQL and PHP.  Not to mention any improper behavior by those working at my hosting company or ISP. 

I'm feeling much better now.

So let's move on to the question of non-repudiation.  There is no such thing as a provably correct system of any significant size.  So there is no such thing as non-repudiation in an end-to-end sense.  The fact that this term emerged from the world of PKI is yet another example of its failure to grasp various aspects of reality.

There is no way to prove that a key has not been compromised – even if a fingerprint or other biometric is part of the equation.  The sensors can be compromised, and the biometrics are publicly available information, not secrets.

I'm mystified by people who think cryptography can work “in reverse”.  It can't.  You can prove that someone has a key.  You cannot prove that someone doesn't have a key.  People who don't accept this belong in the ranks of those who believe in perpetual motion machines.

To understand security, we have to leave the nice comfortable world of certainties and embrace uncertainty.  We have to think in terms of probability and risk.  We need structured ways to assess risk.  And we then have to ask ourselves how to reduce risk. 

Even though I can't prove noone has stolen my key, I can protect things a lot more effectively by using a key than by using no key! 

Then, I can use a key that is hard to steal, not easy to steal.  I can put the lock in the hands of trustworthy people.   I can choose NOT to store valuable things that I don't need. 

And so, degree by degree, I can reduce my risk, and that of people around me.

Richard Gray on authentication and reputation

Richard Gray posted two comments that I found illuminating, even though I see things in a somewhat different light.  The first was a response to my Very Sad Story: 

One of the interesting points of this is that it highlights very strongly some of the meat space problems that I’m not sure any identity solution can solve. The problem in particular is that as much as we try to associate a digital identity with a real person, so long as the two can be separated without exposing the split we have no hope of succeeding.

For so long identity technical commentators have pushed the idea that a person’s digital identity and their real identity can be tightly bound together then suddenly, when the weakness is finally exposed everyone once again is forced to say ‘This digital identity is nothing more than a string puppet that I control. I didn’t do this thing, some other puppet master did.’

What’s the solution? I don’t know. Perhaps we need to stop talking about identities in this way. If a burglar stole my keys and broke into my home to use my telephone it would be my responsibility to demonstrate that but I doubt that I could be held responsible for what he said afterwards.  Alternatively we need non-repudiation to be a key feature of any authentication scheme that gets implemented.

In short, so long as we can separate ourselves from our digital identities, we should expect people not to trust them. We should in fact go to great lengths to ensure that people trust them only as much as they have to and no more.

 He continued in this line of thought over at Jon's blog:

As you don’t have CardSpace enabled here, you can’t actually verify that I am the said same Richard from Kim’s blog. However in a satisfyingly circular set of references I imagine that what follows will serve to authenticate me in exactly the manner that Stephen described. 🙂  [Hey Jon – take a look at Pamelaware – Kim]

I’m going to mark a line somewhere between the view that reputation will protect us from harm and that the damage that can be done will be reversible. Reputation is a great authenticating factor, indeed it fits most of the requirements of an identity. It's trusted by the recipient, it requires lots of effort to create, and is easy to test against. Amongst people who know each other well its probably the source of information that is relied upon the most. (”That doesn’t sound like them” is a common phrase)

However, this isn’t the way that our society appears to work. When my wife reads the celebrity magazines she is unlikely to rely on reputation as a measure for their actions. Worse than this, when she does use reputation, it is built from a collection of previous celebrity offerings.

To lay it out simply, no matter who should steal my identity (phone, passwords etc.) they would struggle to damage my relationship with my current employer as they know me and have a reputation to authenticate my actions with. They could do a very good job of destroying any hope I have of getting a job anywhere else though. Regardless of the truth I would be forced to explain myself at every subsequent meeting. The public won’t have done the background checks, they’ll only know what they’ve heard. Why would they take the risk and employ me, I *might* be lying.

Incredibly, the private reputation that Allen has built up (and Stephen and the rest of us rely on) has probably helped to save a large portion of his public reputation. Doing a google for “Allen Herrell” doesn’t find netizens baying for his blood, it finds a large collection of people who have rallied behind him to declare ‘He would not do this’.

Now what I’m about to say is going to seem a little crazy but please think it through to the end before cutting it down completely. So long as our online identities are fragile and easily compromised people will be wary to trust them. If we lower the probability of an identity failing, people will, as a result, place more faith in that identity. But if we can’t reduce the probability of failure to zero then when some pour soul suffers the inevitable failure of their identity, so many more people will have placed faith in it that undoing the damage may be almost impossible. It would seem then that the unreliability of our identity is in fact our last line of defence.

My point then is that while it is useful to spend time improving authentication schemes perhaps we are neglecting the importance of non-repudiation within the system. If it was impossible for anyone other than me to communicate my password string to an authentication system then that password would be fine for authentication and it wouldn’t even be necessary to encrypt the text wherever it was stored!

Windows Financial Services “Best of the Blogs” list

I'm pleased to see the editors of Windows in Financial Services put identityblog on its “Best of the Blogs” list.   Welcome to any readers who “get here from there.” 

It's impressive for a publication so intensely focussed on financial services to invite its readers into a parallel universe which, as the editors put it, “…addresses the innumerable ramifications of this growing problem [identity theft – Kim]…”.  Yup.  There are definitely a lot of ramifications around here.

Identity theft is fast progressing as a huge threat to financial institutions everywhere, especially in the area of online banking.  In his “Identity Weblog,” Kim Cameron, Microsoft’s architect for identity, addresses innumerable ramifications of this growing problem, ranging from illegal sale of stolen credit card information on the Web, to whether or not schoolchildren should be fingerprinted, to technical solutions such as encryption. 

In an April 2nd entry, Kim answers questions from his readers about CardSpace, an encryption technology that can be enabled for .NET 2.0 through the use of Visual Studio 2005 Toolbox for Windows CardSpace. C lick below to read Kim’s advice on subjects such as how CardSpace prevents phishing – even when used in conjunction with passwords – and to find out how to ask him ID-related questions of your own.

So, welcome to any new readers and please make yourselves at home.  Extra bonus:  you'll have a chance to use CardSpace when posting comments.

newtelligence CardSpace API

Sergey Shishkin reports that a new developer's kit will be released by newtelligence AG.

newtelligence AG announces plans to release the newtelligence CardSpace SDK, a Software Development Kit for Microsoft Windows CardSpace. The SDK, based on newtelligence expertise in information security, will help developers build more robust CardSpace-enabled application on the .NET platform – with ease.Microsoft .NET Framework 3.0 was released in November 2006 and introduced Windows CardSpace – a user-centric digital identity solution.

CardSpace allows developers to leverage federated security and single sign-on in their solutions. As a leading security expert company, newtelligence investigated .NET Framework 3.0 and Windows CardSpace starting from its early, pre-released versions and developed technology samples to clearly demonstrate to customers the underlying technology as well as provide best practices for its use.

Although CardSpace is based on the standardized web service security protocols (WS-* standards), developing CardSpace-enabled applications is challenging. Developers have to possess solid knowledge not only in web service security protocols but also in cryptography and XML.

newtelligence SDK for Windows CardSpace will provide a comprehensible API for key CardSpace application scenarios: Programmatic creation of managed information cards; requesting and validating security tokens in Microsoft Windows and web applications; and issuing security tokens. Use of the API will increase software security and developer productivity: Writing secure software is simplified and less software coding is required to achieve the desired, secure functionality. To aid understanding of the SDK and of CardSpace in general, a reference application and additional code samples covering different aspects of the API usage will accompany the SDK.

The newtelligence CardSpace SDK will contain complete source code of the API and is intended for personal use only. For more information regarding availability, licensing or reuse of the SDK, please contact us.

One of Sergey's readers comments:

How about just releasing it instead of announcing the announcement 😉

Sergey responds:

Dominick, the work is in progress now. The release is of course the goal 🙂

I'm glad to see Dominick so itchy.  Sergey says he will host a discussion about the API on his blog.

Without BE, templates ARE your biometrics

The more I learn from Alex Stoianov about the advantages of Biometric Encryption, the more I understand how dangerous the use of conventional biometric templates really is.  I had not understood that the templates were a reliable unique identifier reusable across databases and even across template schemes without a fresh biometric sample.  People have to be stark, raving mad to use conventional biometrics to improve the efficiency of a children's lunch line.

Alex begins by driving home how easy template matching across databases really is:

Yes, that’s true: conventional biometric templates can be easily correlated across databases. Most biometric matching algorithms work this way: a fresh biometric sample is acquired and processed; a fresh template is extracted from it; and this template is matched against previously enrolled template.

If the biometric templates are stored in the databases, you don’t need a fresh biometric sample for the offline match – the templates contain all the information required.

Moreover, this search is extremely fast, such as 1,000,000 matches per sec is easily available. In our example, it would take only 10 sec to search a database of 10,000,000 records (we may disregard for now the issue of false acceptance – the accuracy is constantly improving). Biometric industry is actively developing standards, so that very soon all the databases will have standardized templates, i.e. will become fully interoperable.

BE, on the other hand, operates in a “blind” mode and, therefore, is inherently a one-to-one algorithm. Our estimate of 11.5 days for just one search makes it infeasible at present to do data mining across BE databases. If the computational power grows according to Kim’s estimates, i.e. without saturation, then in 10 – 20 years the data mining may indeed become common.

Kim already suggested a solution – just make the BE matching process slower! In fact, the use of one-way slowdown functions (known in cryptography) for BE was considered before. The research in this area has not been active because this is not a top priority problem for BE at present. In the future, as long as the computer power grows, every time the user gets re-enrolled, the slower function will be applied to keep the matching time at the same level, for example, 1 sec.

Other points to consider:

  • BE is primarily intended for use in a distributed environment, i.e. without central databases;
  • the data mining between databases is even much easier with users’ names – you wouldn’t even need biometrics for that. We are basically talking about biometric anonymous databases – a non-existing application at present;
  • if a BE database custodian obtains and retains a fresh biometric sample just to do data mining, it would be a violation of his own policy. In contrast, if you give away your templates in conventional biometrics, the custodian is technically free to do any offline search.

These arguments are beyond compelling, and I very much appreciate the time Alex and Ann have taken to explain the issues.

It's understandable that BE researchers would be concentrating on more challenging aspects of the problem, but I strongly support the idea of building in a “slowdown function” from day one.  The BE computations Alex describes lend themselves perfectly to parallel processing, so Moore's law will be operating in two, not one, dimensions.  Maybe this issue could be addressed directly in one of the prototypes.  For 1:1 applications it doesn't seem like reduced efficiency would be an issue. 

Why couldn't the complexity of the calculation be a tunable characteristic of the system – sort of like the number of hash iterations in password based encryption (PBE)?

Clarifications on biometric encryption

Ann Cavoukian and Alex Stoianov have sent me a further explanation of the difference between the “glass slipper effect”, which seems to be a property of all biometric systems, and the much more sinister use of biometric templates as an identifying key.

Kim raises an interesting point, which we would like to address in greater detail:

“This is a step forward in terms of normal usage, but the technology still suffers from the “glass slipper” effect. A given individual's biometric will be capable of revealing a given key forever, while other people's biometrics won't.  So I don't see that it offers any advantage in preventing future mining of databases for biometric matches. Perhaps someone will explain what I'm missing.”

Let us consider a not-so-distant future scenario.  When the use of biometrics grows, an ordinary person will be enrolled in various biometrically controlled databases, such as travel documents, driver licenses, health care, access control, banking, shopping, etc. The current (i.e. conventional, non-BE) biometric systems can use the same biometric template for all of them. The template becomes the ultimate unique identifier of the person. This is where the biometric data mining comes into effect: the different databases, even if some of them are anonymous, may be linked together to create comprehensive personal profiles for all the users. To do this, no fresh biometric sample is even required. The linking of the databases can be done offline using template-to-template matching, in a very efficient one-to-many mode. The privacy implications explode at this point.

Contrast that to BE: it would be much more difficult, if not impossible, to engage in the linkage of biometric databases. BE does not allow a template-to-template matching — the tool commonly used in conventional biometrics. In each BE database, a user has different keys bound to his biometric. Those templates cannot be matched against each other. You need a real biometric sample to do so. Moreover, this matching is relatively slow and, therefore, highly inefficient in one-to-many mode. For example, running a single image against 10,000,000 records in just one BE database could take 0.1 sec x 10,000,000 = 1,000,000 sec = 11.5 days.

Kim is basically correct in stating that if an individual's real biometric image was somehow obtained, then this “glass slipper” could be used to search various databases for all the different PINs or keys that “fit” and, accordingly, construct a personal transaction profile of the individual concerned, using data mining techniques. But you would first have to obtain a “satisfactory” real image of the correct biometric and or multiple biometrics used to encrypt the PIN or key. All of the PINs or keys in the databases can and should be unique (the privacy in numbers argument) — as such, if an individual's actual biometric could somehow be accessed, only an ad hoc data mining search could be made, accessing only one entry (which would represent an individual privacy breach, not a breach of the entire database).

However, with BE, the actual biometric (or template derived from that biometric) is never stored – a record of it doesn’t exist. Without the actual biometric, data mining techniques would be useless because there would be no common template to use as one's search parameter. As mentioned, all the biometrically encrypted PINs or keys in the databases would be unique. Furthermore, access to the individual's biometric and associated transaction data would be far more difficult if a biometrically encrypted challenge/response method is employed.

In contrast, current biometric methods use a common (the same) biometric template for an individual’s transactions and, accordingly, can be used as the search parameter to construct personal profiles, without access to the real biometric. This presents both a privacy and security issue because not only could profiles be constructed on an ad hoc basis, but each template in a database can be used to construct profiles of multiple individuals without access to their real biometric. We thus believe that this alone makes biometric encryption far superior to standard current biometric methods.

Ann Cavoukian and Alex Stoianov

I had not understood that you can so easily correlate conventional biometric templates across databases.  I had thought the “fuzziness” of the problem would make it harder than it apparently is.  This raises even more red flags about the use of conventional biometrics.

Despite the calculation times given for BE matching, I'm still not totally over my concern about what I have called the glass slipper effect.  It would be a useful area of research to find ways of making the time necessary to calculate the BE match orders of magnitude longer than is currently the case.  If today it takes 11.5 days to search through 10,000,000 records, it will only take 4 hours in ten years.  By then the kids we've been talking about will be 16.  Won't that make it less than a minute by the time they are 26?  Or a quarter of a second when they're in their mid thirties?

One very sad story

This article by ZDnet's Mitch Ratcliffe on Identity Rape and Mob Mentality sends shivers down the spine.  Partly because a bunch of our friends are involved.  Partly because the dynamics are just scarey.

Allen Herrell, one of the accused attackers in the Kathy Sierra controversy, has written a long email to Doc Searls explaining that his entire online identity has been compromised. If true, and I believe it, because I have known Allen for many years, it appears there have been many more victims here than Ms. Sierra.

I am writing this from a new computer, using an email address that will be deleted at the end of this.

I am no longer me. My main machine despite my best efforts has been hacked, my accounts compromised including my email. and has been disconnected from the internet.

How did this happen? When did this happen? shit doc, i don't have a fucking clue. I thought i was pretty sharp. I guess not.

just about every online account that i have has been compromised. Most importantly my digital identity and user/password for typepad and wordpress. I have been doing damage control, for my clients. How the fuck i got to be part of this mess is revolting.

The Kathy Sierra mess is horrific. I am not who ever used my identity and my picture!!

I am sick beyond words over this whole episode. Kathy Sierra may not be on my top 10 list , but nobody deserves this filthy character assaination (sic). 

A lynch mob mentality has come over the Blogosphere. Kathy Sierra has ever right to be angry about the messages directed at her, but her allegations appear to have been misdirected and misinformed, because they relied on simplistic analysis of the sites and assumed that appearance and reality were identical. And she's making it worse, writing today:

You're damn right I'm *linking* these folks to these posts. You're wrong about their involvement. The posts and comments were NOT made by–as you said–heinous trolls.

Whoever made the posts was a registered member, and they *know* who made the comments — he was one of their participants. I never said Jeaneane was the one creating the noose picture or comment. I said she was a participant in and “celebrated” and encouraged meankids.org. I believe that when prominent people encourage this kind of behavior, they don't get to wash their hands of it, ethically.

I should be more clear, though, that while *someone* broke the law with the noose photo/comment, I'm definitely NOT suggesting that anyone else did anything legally wrong.

But I think Hugh put it better than I can:

–You might not be the guy raping the cheerleader, but if you're the one standing by saying, “go go go!” you share some responsibility.–

Not legal, but ethical. I don't believe any of these folks should be able to create these forums, *celebrate* them, send people there, and actively participate… and then claim complete innocence. If you hand someone a loaded gun. and encourage them to shoot…

The rape metaphor applies to everyone involved who had words and images they find deplorable attributed to them. But it is far more important to understand that the rape claimed attributed to them probably didn't happen wasn't their doing in the first place. The gun shoved in Chris Locke, Jeneane Sessums, Frank Paynter and Allen Herrell's hands is as likely to be illusory as not. We need proof, not accusations, just like in the physical world.

Trolls created the impression of a crime and sat back to watch human nature show its worst side. They are still enjoying it.

As Chris Locke explained in his email to me yesterday, he took the offensive postings down “shortly after it appeared.” Nevertheless, Bert Bates, Kathy Sierra's Head First Java co-author has commented on this blog, saying “By definition, these ‘posts’ were made by the author(s) of the site – it IS a small circle of candidates.” When you factor in the possibility that accounts were co-opted, according to this definition, anyone who has ever had their email address spoofed is responsible for the content of the messages sent under their name.  (Post continues here…)

There are so many things to be learned from this story that it boggles my mind. 

It brings back a conversation I had with Allen (The Head Lemur) at Ester Dyson's Release 1.0 conference, years ago, where we first talked about identity.  He was skeptical (as is his wont) but I had good fun talking to him.  And there is no doubt in my mind that we should, as our civilization has learned to do, consider Allan innocent until proven guilty – and there doesn't seem to be any sign of that. 

The worst is that I hear stories like this all the time.  Not just in my work, but from my family. 

My daughter tells of a lady friend who's gmail account was broken into – resulting in pandemonium that – if it weren't so unbearable – would be the stuff french farces are made of. 

My son's instant messaging account was hacked by the ex of a ladyfriend he wasn't even dating.  Again, he was dragged through weeks of confusion and reconnection. 

So one of the things that separates this story from all the others happening all over cyberspace is just that we know the people involved.  The broad strokes are common today given the randomness of web security and identity.

To make matters worse, imagine technical people saying, in a world of passwords and keystroke loggers, “these ‘posts’ were made by the author(s) of the site – it IS a small circle of candidates…”  Help me.

It's a great proof point that even though blogs don't involve high finance, they still need high quality security.  The loss of privacy and loss of dignity we have witnessed here can't really be undone, even if one day they can be forgotten.  Protecting identity and protecting access is not a joke.

Some days, when I'm really tired, I look at the vast job ahead of us in fixing the internet's identity infrastructure, and wonder if I shouldn't just go and do something easy – like levitation.  But a story like this drives home the fact that we have to succeed. 

Maybe next time Allan and colleagues will be using Information Cards, not passwords, not shared secrets.  This won't extinguish either flaming or trolling, but it can sure make breaking in to someone's site unbelievably harder – assuming we get to the point where our blogging software is safe too.

Biometric encryption

This diagram from Cavoukian and Stoianov's recent paper on biometric encryption (introduced here) provides an overiew of the possible attacks on conventional biometric systems (Click to enlarge; consult the original paper, which discusses each of the attacks).

Click to enlarge

Having looked at how template-based biometric systems work, we're ready to consider biometric encyption.  The basic idea is that a function of the biometric is used to encrypt (bind to) an arbitrary key.  The key is stored in the database, rather than either the biometric or a template.  The authors explain,

Because of its variability, the biometric image or template itself cannot serve as a cryptographic key. However, the amount of information contained in a biometric image is quite large: for example, a typical image of 300×400 pixel size, encoded with eight bits per pixel has 300x400x8 = 960,000 bits of information. Of course, this information is highly redundant. One can ask a question: Is it possible to consistently extract a relatively small number of bits, say 128, out of these 960,000 bits? Or, is it possible to bind a 128 bit key to the biometric information, so that the key could be consistently regenerated? While the answer to the first question is problematic, the second question has given rise to the new area of research, called Biometric Encryption

Biometric Encryption is a process that securely binds a PIN or a cryptographic key to a biometric,so that neither the key nor the biometric can be retrieved from the stored template. The key is re-created only if the correct live biometric sample is presented on verification.

The process is represented visually as follows (click to enlarge):

Click to enlarge

Perhaps the most interesting aspect of this technology is that the identifier associated with an individual includes the entropy of an arbitrary key.  This is very different from using a template that will be more or less identical as long as the template algorithm remains constant.  With BE, I can delete an identifier from the database, and generate a new one by feeding a new random key into the biometric “binding” process.  The authors thus say the identifiers are “revokable”.

This is a step forward in terms of normal usage, but the technology still suffers from the “glass slipper” effect.  A given individual's biometric will be capable of revealing a given key forever, while other people's biometrics won't.  So I don't see that it offers any advantage in preventing future mining of databases for biometric matches.  Perhaps someone will explain what I'm missing.

The authors describe some of the practical difficulties in building real-world systems (although it appears that already Phillips has a commercial system).  It is argued that for technical reasons, fingerprints lend themselves less to this technology than iris and facial scans. 

Several case studies are included in the paper that demonstrate potential benefits of the system.  Reading them makes the ideas more comprehensible.

The authors conclude:

Biometric Encryption technology is a fruitful area for research and has become sufficiently mature for broader public policy consideration, prototype development, and consideration of applications.

Andy Adler at the University of Ottawa has a paper looking at some of the vulnerabilities of BE.

Certainly, Cavoukian and Stoianov's fine discussion of the problems with conventional biometrics leaves one more skeptical than ever about their use today in schools and pubs.