Reversing a Fingerprint Reader Protocol (2021)

https://blog.th0m.as/misc/fingerprint-reversing/

58•thejj100100•3d ago

Comments

abstractspoon•3d ago

Excellent

Liftyee•7h ago

Damn, I always thought that the fingerprint data was encoded somehow and never left the sensor hardware itself! OS-level access to the imagery seems like a security risk, but also opens some interesting possibilities for alternative uses.

jeroenhd•6h ago

AFAIK it depends per reader. This one seems to be a weird webcam on steroids, but others do the matching locally.

IIRC, none of them do it particularly securely.

cinntaile•4h ago

What's the security status of fingerprints on phones? Surely they don't leave the security chip? I hope?

maxhille•4h ago

I don't think fingerprints should be regarded as a secret.

ta8645•3h ago

Can you please post a link to high quality images of your own fingerprints? It should be fine, probably nobody has the technology to make them show up on a threatening letter mailed to the government, or anything like that.

maxhille•2h ago

Of course I won't, but then again I would send you pictures of any other body parts the same.

If someone gets a hand on anything you touched, they have your fingerprint. Last time you traveled to another country - did you have to give them fingerprints? Is the software running your phone closed source? Could you ambush me at night near my house and forcefully take them?

All I am saying is they are so weak as a secret that rhey should not be regarded as one.

JJJollyjim•7h ago

As noted in the article I reversed the protocol for a related Goodix device (which was on Intel so used actual SGX instead of the white-box): I used the firmware update system to insert additional vulnerabilities in the sensor firmware and extract the PSK from that side.

I did a talk about it here: https://www.youtube.com/watch?v=IyjUY-xvFw4

th0mas•3h ago

Author here, didn't expect to see this on HN today! If you've got any questions, shoot!

unlucky666•1h ago

Do you have more posts similar to this one? Noticed your blog was a bit empty...

th0mas•40m ago

Ha yeah I should really get on updating some of the info there. Got derailed with work quite a bit.

Most recently did some work on BitLocker: https://news.ycombinator.com/item?id=42747877

ge96•3h ago

The real work ha underneath the software eg. I can't write a camera driver but thankfully someone else can

That's cool the raw data image GIMP

johnflan•1h ago

I didn't follow the byte ordering of the image format at the end. Anyone have an explanation?

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