Prepare Captured Samples for Analysis

This doc outlines the steps that need to be taken to prepare the samples for the analysis tool.

Assume the following definitions:

• <PATH_TO_SAMPLES> is the root directory of of the samples that contains the participant ID directories.
• <PRIVATE_KEY_PASSWORD> is the password for the chromeos-fpstudy-private.gpg generated by gen-key-pair.sh.
• <PATH_TO_PRIVATE_KEY> is the path to the chromeos-fpstudy-private.gpg created by gen-key-pair.sh.

A. Setup Environment for fpstudy.py

1. Install package dependencies

   • If on Debian or gLinux, run the following command:

     sudo apt install python3-gnupg imagemagick
     

   • If on Gentoo or ChromiumOS SDK, run the following command:

     sudo emerge media-gfx/imagemagick dev-python/python-gnupg
     

2. Add to PATH

   PATH=~/chromiumos/src/platform2/biod/study:"${PATH}"
   

   You can add this to you ~/.bashrc, if you want it to persist across shell launches.

B. Decrypt Samples

cd <PATH_TO_SAMPLES>
# For single threaded operation, use the following command:
#fpstudy.py decrypt --password '<PRIVATE_KEY_PASSWORD>' <PATH_TO_PRIVATE_KEY> .
# For parallel operation, use the following command:
ls ./ | xargs -P$(nproc) -L1 fpstudy.py decrypt --password '<PRIVATE_KEY_PASSWORD>' <PATH_TO_PRIVATE_KEY>

C. Generate PNG Samples [optional]

Generating PNG samples can help debug invalid samples.

cd <PATH_TO_SAMPLES>
# For single threaded operation, use the following command:
#fpstudy.py convert <FPC1025|FPC1145> png .
# For parallel operation, use the following command:
ls ./ | xargs -P$(nproc) -L1 fpstudy.py convert <FPC1025|FPC1145> png