Anonymize ULog Data

Ever wanted to remove sensitive information from your ULog such as GPS data or anonymize it? This is a solution for you!

This repository contains a script that can modify your GPS location data inside ULog to an arbitrary point.

Showcase

Here we have the raw data plotted using a Plotjuggler:

After applying anonymization, data plotted turns into this:

It may be hard to notice, but notice how the vertical scale has changed (absolute value of the global position). Now the vehicle starts from (0, 0) in this given example screenshot.

The relative latitude / longitude differences during operation are still visible, but the absolute location is shifted so that the original location is not traceable.

What the script does

GPS coordinate anonymization

Script modifies the following uORB topics to anonymize the GPS Latitude / Longitude data:

• home_position
• vehicle_local_position
• estimator_local_position
• estimator_global_position
• vehicle_global_position
• vehicle_gps_position
• sensor_gps

Note, altitude data is not modified!

The anonymization is done by adding a pseudo-random latitude/longitude offset.

So the vehicle will appear to take-off / arm from the fixed arbitrary location, regardless of the actual global position it had after going through anonimization.

Anonymized information

It also adds a new Information message key-value pair into the uLog:

"postprocessing.anonymized" : 1 (True)

How to use the script

Clone the repository

Note, this repository relies on the submodule pyulog. So you must clone the repository with --recursive option to clone the submodules as well!

git clone https://github.com/junwoo091400/Anonymize_ULog_Data.git --recursive

Activate python virtual environment

python3 -m venv venv
source venv/bin/activate

Install the pyulog in the venv

To use the pyulog properly (and install all of it's dependencies), the best option is to install the pyulog in the virtual environment. For which you can do the following:

cd pyulog/
python setup.py build install
cd ..

Execute the script

Example command (with the example ulog file supplied):

python3 anonymize_gps_data.py --output_dir ./logs logs/log_5_LongCruise_And_TwoRescues_19-53_17_29_18.ulg

Here's the usage:

anonymize_gps_data.py [-h] [-o OUTPUT_DIR] [-v VERBOSE] ulog_path
anonymize_gps_data.py: error: the following arguments are required: ulog_path

Additional Context

Pyulog bug on exporting transponder_report topic

It seems like for logs with transponder_report topic, the pyulog breaks down when trying to export the file.

This has been addressed in a PR, but the log export may fail with the message "struct.error: char format requires a bytes object of length 1".

Magnetometer data

The magnetometer data (e.g. vehicle_magnetometer) can give an information about an approximate location of the vehicle using the declination information.

However, this information is not modified in the script yet.

Plotjuggler Layout

The layout useful for viewing the lat / lon values in Plotjuggler is attached in the repository here.

You can apply this layout by clicking "File" > "Load layout" in Plotjuggler.