https://github.com/clarkfieseln/audiocat
Command-line utility that reads and writes encrypted data across peer-to-peer audio connections, using minimodem and gpg
https://github.com/clarkfieseln/audiocat
audio client-side-scan data-diode e2ee-encryption encryption encryption-decryption gnupg gpg linux linux-shell mass-surveillance minimodem modem python python3 real-time remote-control reverse-shell shell-script
Last synced: about 1 year ago
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Command-line utility that reads and writes encrypted data across peer-to-peer audio connections, using minimodem and gpg
- Host: GitHub
- URL: https://github.com/clarkfieseln/audiocat
- Owner: ClarkFieseln
- License: mit
- Created: 2024-08-09T12:06:08.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2025-02-17T09:30:42.000Z (over 1 year ago)
- Last Synced: 2025-02-17T10:29:47.818Z (over 1 year ago)
- Topics: audio, client-side-scan, data-diode, e2ee-encryption, encryption, encryption-decryption, gnupg, gpg, linux, linux-shell, mass-surveillance, minimodem, modem, python, python3, real-time, remote-control, reverse-shell, shell-script
- Language: Shell
- Homepage:
- Size: 29.8 MB
- Stars: 3
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# audiocat
Audiocat is a command-line utility for Linux that reads and writes encrypted data across peer-to-peer or broadcast audio connections, using [minimodem](https://github.com/kamalmostafa/minimodem "minimodem") and [gpg](https://github.com/gpg/gnupg "gpg").
It is a powerful tool that can be combined with any audio infrastructure (like PSTN, cellular network, internet, radio, walkie-talkies) to provide a secure communication channel through an audio tunnel.
The audio interfaces behave like data-diodes, each allowing unidirectional data transmission only, thus preventing data-leaks and malware-injection.
This enables an "enhanced"-end-to-end encryption (E-E2EE) which notably increases security and privacy, especially when the end devices are completely offline (air-gapped-system), thus providing an effective barrier against "legal or illegal" client-side-scanning!
See also
## Installation
```
pip install audiocat-clark
```
or with git:
```
git clone https://github.com/ClarkFieseln/audiocat.git
cd audiocat_clark
chmod +x audiocat
chmod +x *.sh
```
during first execution you will be asked to install dependencies: minimodem, gpg, bc
but you can also install them yourself with:
```
sudo apt install minimodem
sudo apt install gpg
sudo apt install bc
```
The package gnome-terminal is assumed to be already installed, install otherwise or change cfg/terminal.
## How to use (pip installation)
### Chat/Messenger
```
audiocat -c
```
enter and confirm password
On the other device a chat or a remote shell can be started.
### Remote Shell
```
audiocat -s
```
then enter and confirm password
On the other device a chat shall be started to command the remote shell.
Note that this is technically a "reverse shell" which gives access to your system!
### File Transfer
```
audiocat -f
```
enter and confirm password
On the other device a file transfer shall be started.
### Probe
To check connectivity and adjust volumes if required.
```
audiocat -p
```
In addition, a separate terminal will be opened to read unencrypted probe messages being sent by the other side.
## Configuration
Adapt the configuration as required using the 'terminal GUI' with:
```
audiocat -g
```
Alternatively, you may change the configuration by editing the files in the cfg folder directly. The 'Location' can be found with:
```
audiocat -d
```
The most important settings are:
* baud
* keepalive_time_sec
* retransmission_timeout_sec
* split_tx_lines
* volume_microphone
* volume_speaker_left
* volume_speaker_right
## How to use (git installation)
When installed with git, audiocat may be called with:
```
python3 audiocat.py -c
# or
./audiocat -c
```
This is an example to start a chat, but this is the same for any other option.
For more information check the [documentation](https://github.com/ClarkFieseln/audiocat/blob/main/doc/documentation.md).
## Features
on top of the audio modem provided by minimodem and encryption provided by GPG, audiocat offers a reliable transport layer and many other features:
- modes: chat, remote-shell, file transfer (future: sniffer)
- full-duplex communication
- retransmit messages automatically after communication errors
- split big messages into smaller data chunks in order to increase the probability of reception, thus reducing retransmissions
- [keepalive] messages
- redundant transmission of "data-messages"
- composition of piped commands hidden to the user
- tmp folder located in a configurable path beneath $HOME, independent of the current path.
- probe, to check volume on receiver and adjust manually if needed
(very high and very low volumes may produce signal distortions)
- "braodcast" transmissions also possible, e.g. when ACKs are deactivated
use-case: walkie-talkie, Radio station, ...
- several configuration options: preamble, trailer, delays, cipher algorithm, confidence, log to file, verbose, etc.
## Possible Abuses
please don't do the following if you are not allowed (it might be illegal!):
- exfiltrate data over the air or cable to a nearby or remote computer
- remote control over the air or cable from a nearby or remote computer
- exfiltrate data from a computer evading classical auditing
(be aware that if you do this on your employer's computer you might be infringing the law!)
- use the tool as a "side-channel" for covert communication e.g. to spread or inject malware,
even worse when combined with steganography (e.g. low volumes, data hidden in noise)
## Typical Configuration
A: audiocat in offline PC (Alice)
D: audiocat in offline PC (Bob)
B, C: smartphone with call session (mobile, messenger app, etc.)
diodes: audio connections (sink/speaker -> source/microphone)
## Communication in Linux over Linphone
A: audiocat in offline PC (Alice)
D: audiocat in offline PC (Bob)
B, C: smartphone with [Linphone](https://www.linphone.org) call session
## Communication in Termux over qTox
A: audiocat in offline smartphone with Termux (Alice)
D: audiocat in offline smartphone with Termux (Bob)
B, C: PC with qTox call session
## Communication in Linux over Walkie Talkies
## Split Configuration
A: audiocat in offline PC (Alice)
D: audiocat in offline PC (Bob)
B1, B2, C1, C2: waklie-talkie
## Limitations
The data transfer is usually done at low rates, typical of audio systems. Therefore, this tool is not adequate to transmit big files which may take a long time to complete.
## Hints
Avoid using tools like PulseEffects, they may produce glitches!
In PuseEffects you may check the 'Add to Block List' option for minimodem and qtox.
## PyPi Project
https://pypi.org/project/audiocat-clark
## GitHub Project
https://github.com/ClarkFieseln/audiocat
## Documentation
https://github.com/ClarkFieseln/audiocat/blob/main/doc/documentation.md
## Screenshots
https://github.com/ClarkFieseln/audiocat/tree/main/screenshots
## Videos
https://www.youtube.com/playlist?list=PLX24fhcibpHUx7ej_Tp4neobJUqOkqliN
## License
(c) 2025 Clark Fieseln
This repository is licensed under the MIT license. See LICENSE for details.