Using a belt sander to foil biometric fingerprints | Hacker News Reader

Using a belt sander to foil biometric fingerprints

jacquesmattheij.com

111 pointsLuc67 comments

A belt sander is a bit harsh. The micro-fine sandpapers used by plastic model hobbyists work much better, and are much less likely to harm your fingers.

I remember reading this trick in the old spy novels, and being a model hobbyist at the time, I had to try it (on one finger, anyway). It worked -- so far as eliminating fingerprints. Of course, back then biometrics was a rather exotic technology, low res, and not in common use.

My experience making balsa wood aircraft indicates that the combination of gluing your fingers to a wing with CA, prying them off, then sanding the glue off was a pretty effective way of getting rid of the fingerprints, on one hand at least.

Do it with two hands and it got very hard to pry the first hand off.

How long does it last? I assume the prints "grow back", but what time does it take?

You can do the same with standard address labels as anyone who has sent out a large mail-merge will know.

People would be better of putting their bountiful tin-foil-hat energies to use campaigning against the governments that introduce these laws. Writing a letter to your MP is far more meaningful than grinding off the ends of your fingers.

It's all dependent on your definition of meaningful. If you want to be an activist, writing a letter is an excellent way to go about it. If you want a passport to travel sometime during your lifetime but would prefer to not have to worry too much about privacy concerns, writing a letter isn't going to help you much.

I hardly think it's tin-foil hat territory to look at the state of most Western governments and deduce that they are becoming more fascist and less democratic all the time, completely in the name of preventing terrorism. Sanding your fingertips off and writing a letter to your MP serve two distinctly different prongs of a fight against that fascism.

The 'tin foil hat' madness isn't really in suspecting that there are people out there trying to control your mind. It's in believing that wearing a tin foil hat is going to stop them.

A better plan would be: move somewhere so isolated, electronic media can't reach you?

Any plans that don't result in shortened life span?

The title really should read, "Using a belt sander to ensure your biometric prints never match your actual prints".

Jacques is in for a world of hurt when he next travels abroad.

Jacques is in for a world of hurt when he next travels abroad.

To my knowledge, it's ONLY the U.S. that finger-prints foreigners. Jacques is Dutch, and all he has to do to avoid "a world of hurt" is to not come to the U.S.

To my knowledge, it's ONLY the U.S. that finger-prints foreigners

Japan and the USA, I'm pretty sure.

And this system would only catch nationals of the country in question being fingerprinted upon re-entering that country.

Yeah and it doesn't work very well:

http://www.japantoday.com/category/national/view/deported-s-...

This woman snuck back in a few times after being deported by using "special tape." I really wonder how special the tape is. On the other hand:

846 foreign nationals were refused entry

So, I doubt they will ever get rid of the program.

> I really wonder how special the tape is.

There's some blister plasters that are very thin and transparent.

Herpes plasters for around the mouth are quite hard to spot (though with a picture as blurry as in this article you would expect them to be): http://www.primped.com.au/blogs/zoes-blog/if-you-get-cold-so...

Not true, there are plenty of countries that you get fingerprinted in. I get printed when I go to Saudi Arabia, for example.

Many countries have taken to printing Americans, only because their citizens get printed by America.

At least according to Americans :)

I get fingerprinted all the time and I'm not American. Maybe I just look shifty.

I used to work for immigration (IT dept) in my country - in South America.

There where always plans to start finger-printing foreigners, though nothing has been done to this day.

As far as I know, there's not a single country in South America that finger-prints tourists. I believe Brazil does finger print US citizens though, but that was only after the US started finger printing them.

> Jacques is in for a world of hurt when he next travels abroad.

Probably because I'm 6'3 and don't fit well into economy class sea-

oh, the other Jacques.

I had a cousin who worked construction (and consequently didn't really have fingerprints).

He also got arrested a lot (like most of my family) and they took to taking palm prints when they booked him.

They would grow back if he went awhile without doing work though; it was definitely a temporary solution.

"they took to taking palm prints"

Well, you could sand those off, too. And while you're at it: sand your toes. And your heels.

Now what would you do when iris scans become a commonplace biometric? Sand off the back of your eyeballs? ;-)

Your iris doesn't leave prints on your gun.

I had the opportunity to learn a little bit about fingerprints during a programming gig. The part he's missing here is that what he thinks is a smudge can sometimes still be used as part of a print. Partials aren't just from TV dramas, they get used all of the time in real cases. Also one thing most people don't know about is that prints can be "massaged" by law enforcement in what is essentially a photoshop-like process, so if a human technician can make a fairly good guess about what the print should look like, they still might be able to find a match.

I've heard of people doing this before, removing their fingerprints with a sander..

But I believe the fingerprints will grow back after a while. Couldn't you get into more trouble if they grow back and you are carrying around a passport with no fingerprints in it? Or do you plan to keep sanding them off for the rest of your life? (or the life of the passport)

As the author claimed there are many reasons you may not have had fingerprints. Personally, I would try the tried and trusted 'shrug, I have no idea' method.

They do grow back. Just destroy the chip, then there is no way to read them out again.

Now you have two problems..

Why? Does a chip that cannot be read render your passport invalid?

Only if there's evidence that you destroyed the chip on purpose.

A strong EMP might destroy it without visual clue.

Fingerprints will grow back unless you get down to dermal layers of skin and that will hurt quite a bit. Permanently removing your prints is a more involved process than this, but it's certainly a cute idea.

It's a really funny, whimsical thing to do, but how will this help you to increase your privacy? Next time you enter the US your finger prints won't match the data on your passport, right?

Some of us haven't gotten passports, or been fingerprinted yet. This may be analogous Schmidt's child/adult quip.

They'll also be a perfect match to the last nutjob who filed off his own fingerprints before mailing letterbombs to the IRS.

It probably only increases your chance of being detained, probed and investigated. Unless you file off your face, they can still tell who you are.

Rather than adapting your body to quietly live within the 'instruments of control', why not actively campaign against them?

Why not do both?

Doh, I just realize Jacques won't be replying, since he retired from HN last week...

If you're feeling brave, microwave your passport for good measure.

According to most official documents, any passport which has a faulty rfid will be assumed tampered with, and will become invalid. So unless you want to be refused entry and forced to replace your passport, this is unadvisable.

This is not true for Germany. (Which makes this even more a security theater..)

You could cause even more of a hassle then by building an RFID zapper (http://en.wikipedia.org/wiki/RFID_Zapper). A powerful one that fits inside a suitcase could be set off in an airport concourse, frying a large number of people's chips without them ever knowing (or any damage to the passport itself occurring).

Do it on a busy travel day and suddenly the authorities have to deal with a ton of broken passports. Either they arrest everyone, or they let everyone through.

Of course, you probably couldn't get a suitcase-sized RFID zapper through security, but you could show up, set it off a few times, and then leave without arousing TOO much suspicion.

Hell you could just do it on the airport shuttle bus.

Or at the passport issuing office. Now that would be chaos.

So, you're essentially promoting terrorism… neat.

From the point of view of the TSA, maybe. In reality, it's just talking and sharing information.

I've had border guards order me to replace a passport that I carried with me in a rainstorm. It was perfectly readable, but they didn't like the way it had visible damage. Maybe the "security" features were less checkable.

That was in the days before RFID. My passport has a bar-code and every entrance station already has a reader, so RFID is redundant anyway.

Or build a RIFD_Zapper:

http://en.wikipedia.org/wiki/RFID_Zapper

I really like the RFID entrance I get when traveling back to New Zealand... especially after a 13 hour plane ride!

The tourists and kiwis with old passports all line up in a giant queue, while myself and a few others walk up to some machines, scan our passports, have a quick photo taken, and then just stroll on in!

I've flown to NZ with just carry-on luggage and caught a cab within 10 minutes of the plane doors being opened.

It's certainly convenient, but then the authorities can track where you were/where you're going. I don't know if they do the same when manually checking the passport, but I'll assume they don't?

I've been to Peru a few times in the past couple years. Every time I passed through the immigration counter, they swiped my passport through a reader, and up on the customs officer's screen came a list of my travels since getting my current passport. Yeah, Peru sees a lot of tourism traffic -- more than many countries, but they're also not exactly first world, and technology penetration is spotty, at best.

So, yes, they do track you.

(FTR, my passport is pre-RFID.)

It depends.

Just about any passport issued in the past decade or so has a machine-readable text strip on the photograph page. When the passport control officers take your passport they don't just compare your passport photo to your face -- they swipe the passport.

The RFID chip just allows them to store more data and get at it faster than the older machine-readable passports. The information that your passport (and its bearer) have arrived in country X is still available to country X's immigration database the moment you're past the checkpoint.

(Other risks of RFID passports include tracking or cloning, if the owner isn't keeping it in a tinfoil wallet or if the issuing agency's private key gets leaked. See also discussions on comp.risks passim.)

They definitely do; that's the whole reason why you are required to have a passport in the first place. RFID just makes the process more efficient; there's nothing on the chip that isn't contained within the combination of your passport number and their database.

What would be more interesting, would be if he found a way to grow different fingerprints.

Perhaps laser engraving.

Gummy Bears: http://www.schneier.com/crypto-gram-0205.html#5

I feel like this is a little mis-titled. I expected a method to do something to a biometric scanner, or to temporarily alter your fingerprints, not to remove them entirely! Interesting read I suppose, if you're into that sort of thing.

This is a temporary alteration. Fingerprints grow back.

A method to do something to a biometric scanner, using a belt sander?

Somehow I don't think that would really be relevant for the "they're checking my fingerprints at the passport office" situation.

The interesting thing is that fingers with the prints removed actually always do have damages that make them unique. In fact, it is usually easier to identify a print from your fingers now, than before. So good luck with that.

Isn't that a very temporary solution. How long until everything is based on genes, face recognition and so on? For all I know those governments taking my fingerprints might use them to extract my DNA, too.

"It is estimated that 1 in 50 people do not have prints or prints clear enough to be registered by the fingerprint readers currently in use."

Can you provide a source? I'd be interested in seeing data to back this up.

Dig a 1m deep, 5m long trench in your garden with pickaxe and spade. I guarantee you that you won't have the slightest trace of a fingerprint on both hands for quite a while.

Given the number of people working regularly with such tools, that's quite a sizeable number of smooth hands :)

It is estimated that 1 in 50 people do not have prints or prints clear enough to be registered by the fingerprint readers currently in use.

Really!?

I don't know just how accurate the 1 in 50 number is but it is pretty close to my observations. I worked on a fingerprint recognition system several years ago and collected many thousands of live fingerprints and processed hundreds of thousands of other records (scans of inked prints for example). Recognizing a good quality print is almost trivially easy. Most of the work is pulling good information out of low quality images.

Fingerprints are a reliable source of information in most cases for most people but are a far cry perfect form of identification most people think.

So tell us.. Wouldn't being "that guy with no fingerprints" be a more clear identifier, and draw more attention to yourself, than just having the same boring blurry imperfect fingerprints that the rest of us have?

If the goal is to increase your privacy, walking around with sanded off fingerprints sounds about as contrary to that goal as walking around with one of those fake eyeglass-nose-mustache disguises.

It would seem best to sand your fingerprints to the point where they still produce an image, but one that is too low quality to stand up in court, yet is still within the 'normal' bounds and won't arouse suspicion.

Ceramists and brick layers often have vague or worn-off fingerprints. Just say you do a lot of ceramics.

I came to mention that I do some ceramics and hadn't thought about losing fingerprints before but definitely have pretty smooth fingers now. Using grogged clay to throw with can be torture on your hands if you're not used to it.

Like someone mentioned I imagine the prints can be gathered directly by a photographic imaging method - my fingertips are smooth but they still have visual fingerprint patterning. Perhaps if I'm throwing more regularly that would go?

Probably not that much. I would say it's like shaving your head to disguise your hair color. Most people don't have shaved heads but enough do that it wouldn't make you stand out too much.

I used to have severe atopic eczema on my hands and fingers (it cleared up about a decade ago, before the fingerprint nonsense came in). Typically between 2 and 6 of my fingers at any time would be so swollen or inflamed that the fingerprint was distorted or entirely absent. This varied over time.

Eczema isn't that uncommon (although mine was pretty severe) and frequently affects the fingers and hands (as well as elbows and backs of knees). If the biometric-with-fingerprint passports had been standard back then I'd have been in a world of hurt, with fingerprints morphing over a period of multiple months.

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