Hacker News Reader

Comment by speeder | Hacker News Reader

Your username is even appropriate...

I am very worried with Brazil's push to require biometric fingerprits to vote, AND voting being mandatory...

Considering you need to provide fingerprints to request all sorts of documents, what would the government be able to do that they aren't already able now?

Here's a list of documents you need to provide fingerprints, off the top of my head:

– National identity card (RG), mandatory for all citizens over 18 years of age;

– Military conscription certificate (CAM), mandatory for all male citizens over 18 years of age;

– Voting card (Título de Eleitor), mandatory for all citizens between 18 and 65 years of age, encouraged for all citizens over 16;

– Employment record book (Carteira de Trabalho), mandatory for any formal employment;

– Passports

Also, as of at least three years ago in the state of Rio de Janeiro, some of these were already computerized.

In my state these were all just printed on the document (at least last time I had to make documents).

You cannot "hack" a piece of paper easily...

But with mandatory vote + mandatory fingerprint to vote, you just turn that database in a giant juicy target, an attacker can be sure that all voters will have fingerprints there.

Do you have any assurances your paper documents were not immediately scanned? Do you know what kind of access controls are enforced on the file cabinet they're stored in? Are they susceptible to a janitor who gets approached by a shady dude with a briefcase of money? The larger point I'm trying to make is that this is no longer something you have control over and have no guarantees about who else has a copy of it, and therefore should not be relying on it being kept secret, and moreover should assume it has been compromised.

> Considering you need to provide fingerprints to request all sorts of documents, what would the government be able to do that they aren't already able now?

If they already have fingerprints, and now fingerprints are suddenly required for voting, that makes election fraud easier for the government.

How does it make it easier than doing everything the same except not requiring fingerprints?

If you've convinced people that fingerprints prove a person was there and voted, then you have additional weight for your fraud.

You can require biometrics and still not record them. Just use them as a hash lookup into a keystore. The biometric itself would only exist on the server for a few cycles while the key was being looked up. (Very similar to the way credit cards are done)

Unfortunately, that's not how governments around the world require it right now. Estonia for its e-citizenship program, as well as pretty much all countries requiring a fingerprint for passports store the fingerprints in their own centralized database (that also get shared with other nations).

I switched my phone fingerprint to another finger for my phone as soon as I signed-up for a passport.

Wow.

So a piece of plastic the bank gives you with mostly arbitrary numbers on it is better protected than your own fingerprints, which you're stuck with for life?

Good grief.

In the Netherlands we had a passport with fingerprint, and all data stored by the state. Luckily, this was reversed, and now the fingerprint is only stored in the passport itself. Well, that's what I hope, as the fingerprint needs to be stored temporarily for the time to create the passport.

Better, if you don't leave the EU, you can use an identity card that doesn't have the fingerprint.

I was lucky enough to have an old passport that just spanned the period in which the fingerprint was stored centrally. Now I have an ID card, but one time in the future I will leave the EU, and then I have to get a password...

However, Fingerprints cannot be practically hashed.

Images can be hashed(and hashed in such a way that minor changes can still lead to the same hash), so images of fingerprints should be hashable.

Just use them as a hash lookup into a keystore.

This is intuitively appealing, but do biometrics really boil down to an exact number that we could hash like this? (Genuine questions; I don't know.) It seems more likely to me that biometric measurements would be considered to "match" when they're within particular tolerances. This is an operation you can perform on the original measurements, but not on hashes of those.

There is a cryptographic tool called a "fuzzy extractor" that solves this problem (c.f. Fuzzy Extractors: How to Generate Strong Keys from Biometrics and Other Noisy Data, by Dodis, Reyzen and Smith [0]). At enrollment time, you compute some (non-sensitive) data P = Enroll(biometric). Then every time you compute Recover(P, biometric') you will get the same (high-entropy) output, as long as biometric' is close enough to biometric.

[0] https://www.iacr.org/archive/eurocrypt2004/30270518/DRS-ec20...

It is, effectively, what Touch ID does. (It's an over simplification but as an analogy it works)

This sounds like a good idea on the surface but this just shifts the problem.

Ultimately, you still only have 10 fingers (general assumption), and not a large space like 30 char passwords.

Reply on news.ycombinator.com