FocalTech FT9362 Fingerprint Driver

Disclaimer: I am not a real driver developer, nor an NN expert. This driver can and will produce false positives and false negatives. Do not treat this as a complete or secure solution for authentication.

Unfortunately, there is no open-source driver for the fingerprint sensor found in the GPD Pocket 4. There was a build of libfprint with a driver for this device (https://github.com/ftfpteams/focaltech-linux-fingerprint-driver/), but it was removed due to a DMCA request. I tried to reverse-engineer the aforementioned driver, but I was not able to properly reproduce either the image processing or the validation. Most likely, the proprietary driver works much better than mine, but it is no longer available.

During the development of this driver, I tried to implement multiple matching algorithms and image-processing pipelines. However, due to the fact that this sensor has a resolution of 80×76 pixels, it is impossible to extract fingerprint ridges suitable for proper NBIS matching.

What remained was a CNN, and that is exactly what I used for this driver. The dataset for this driver consists only of my own fingerprints. I captured 200 images of each finger using this device, and they were used for training. It would be fair to say that the CNN might work only for me, since it is trained solely on my own fingerprints. However, I doubt this is entirely the case, as at this resolution you can barely distinguish one fingerprint from another.

If you want to create your own dataset, please open an issue or send me an email, and I will try to provide the necessary tooling.

What is it

This is a libfprint driver for the FocalTech FT9362 fingerprint sensor (USB 2808:0752) found in GPD Pocket 4. Essentially libfprint and fprintd are used as glue to communicate with PAM, I am not using NBIS or BZ3 or anything that libfprint provides. Reasons for that are stated above.

Installation (NixOS)

Add to your flake.nix:

{
  inputs.gpd-fp.url = "github:shokerplz/ft9362-driver";

  outputs = { nixpkgs, gpd-fp, ... }: {
    nixosConfigurations.yourhost = nixpkgs.lib.nixosSystem {
      modules = [
        gpd-fp.nixosModules.default
        { services.fprintd-focaltech0752.enable = true; }
      ];
    };
  };
}

Then rebuild:

sudo nixos-rebuild switch --flake .

Usage

fprintd-enroll    # Enroll fingerprint (15 samples)
fprintd-verify    # Verify
fprintd-list $USER

Building from Source

nix build              # Build fprintd with driver
nix develop            # Enter dev shell

Other distributions

If you need a package for your distro - please create an issue and I'll try to figure something out. Or better just create a PR with building scripts.

Technical Details

• Sensor: 80x76 pixel capacitive
• Matching: Siamese CNN with 5-stage verification
• Enrollment: 15 templates stored per finger

License

LGPL-2.1-or-later