Howdy – Windows Hello style facial authentication for Linux

I know there was extensive testing when face recognition authentication came to smartphones. I wonder how an open source project like this one compares. I suspect there are substantially more false positives/negatives than on a commercially developed version that needs to support everyone to be successful.

Apple's Face ID uses what is essentially a 3D camera, a simple 2D color camera cannot compare to that in terms of accuracy.

Windows also uses infrared LEDs to light your face and prevent a flat photo from being recognised as a face.

AFAIK Pixel phones, including the Pixel 9, only use 2D images for face unlock. So it's definitely possible to reach mainstream quality with conventional cameras.

(Unless you'd argue that the face unlock found on Pixels is not passable either)

Apple has clearly done a lot of work in this space and have decided to retain Touch ID on Macbooks. I think this is fairly instructive.

That was primarily because the face id sensor stack is too thick to fit in the laptop lid

The point being that they think they need those sensors in order to create a secure system.

Windows is an operating system and does not have dependence on specific hardware being present.

There are definitely webcams that work with Windows Hello, and those that don't.

Incorrect. Windows Hello uses special hardware.

Right, Windows Hello requires it for facial auth, Windows itself does not. Hello still works, just you have to authenticate with a different method if the hardware isn't present.

I don't know how Google does it, but it's possible to extract 3d information from a 2d sensor. You either need a variable focus or phase detection in the sensor.

"A note on security

This package is in no way as secure as a password and will never be. Although it's harder to fool than normal face recognition, a person who looks similar to you, or a well-printed photo of you could be enough to do it. Howdy is a more quick and convenient way of logging in, not a more secure one.

To minimize the chance of this program being compromised, it's recommended to leave Howdy in /lib/security and to keep it read-only.

DO NOT USE HOWDY AS THE SOLE AUTHENTICATION METHOD FOR YOUR SYSTEM."

It is possible to infer phase from second order intensity via the Huygens-Steiner theorem for rigid body rotation, FWIU: https://news.ycombinator.com/item?id=42663342 .. https://news.ycombinator.com/item?id=37226121#37226160

Doesn't that mean that any camera can be used to infer phase (and thus depth for face ID, which is a high risk application)?

> variable focus

A light field camera (with "infinite" focus) would also work.

Very cool. Yes, probably? I'll have to think about the relationship between image quality and the fidelity of the derived phase measurement, because it's not obvious how good a camera needs to be to be "good enough" for a secure system.

Light field? I remember Lytro! Such cool technology that never found its niche. https://en.wikipedia.org/wiki/Lytro

Is anybody making a successor product?

I guess the task is to design an experiment to test the error between phase inferred from intensity in a digital camera by Huygens-Steiner and a barycentric coordinate map And far more expensive photonic phase sensors.

Is (framerate-1 Hz) a limit, due to the discrete derivative being null for the first n points?

Fortunately this article explained the implications of said breakthrough; "Physicists use a 350-year-old theorem [Huygens-Steiner] to reveal new properties of light waves" https://phys.org/news/2023-08-physicists-year-old-theorem-re... :

> This means that hard-to-measure optical properties such as amplitudes, phases and correlations—perhaps even these of quantum wave systems—can be deduced from something a lot easier to measure: light intensity.

IDK what happened with wave field cameras like the Lytro. They're possibly useful for face ID, too?

"SAR wavefield". There's a thing.

From https://news.ycombinator.com/item?id=32819838 :

> Wave Field recordings are probably [would probably be] the most complete known descriptions of the brain and its nonlinear fields?

How little is your time worth that you spend it making pedantic little correctioms like this?

Bored at work lol