Stegowav

A project exploring WAV-steganography (hiding information in the byte data of a .wav file). It allows encoding text information in a .wav file either via a CLI interface or as a Python library. This is done by modifying a certain number of least significant bits (LSBs) in each amplitude of a wave file. Being the least significant bits these generally are not across an entire file.

Usage

Installation

git clone https://github.com/robert461/cyber-security
pip3 install -r requirements.txt

CLI

List all commands:

$ ./stegowav.py --help
positional arguments:
  input                 input file path

optional arguments:
  -h, --help              show this help message and exit
  -e, --encode ENCODE     encode given text message into wav file
  -d, --decode            decode a text message from wav file if possible
  -o, --output OUTPUT     output file path to be written to
  --overwrite             if the file specified as output should be overwritten
  -t, --encryption_type ENCRYPTION_TYPE
                          encryption type as number to use (0: NONE, 1: FERNET, 2: AES, 3: RSA). 
  -a, --hash_type HASH_TYPE
                          hash type as number to use (0: NONE, 1: PBKDF2, 2: SCRYPT)
  -c, --error_correction_type ERROR_CORRECTION_TYPE
                          error correction type as number to use (0: NONE, 1: HAMMING, 2: REED_SOLOMON)
  -r, --redundant_bits REDUNDANT_BITS
                          number of redundant bits for hamming code
  -l, --lsb LSB           number of least significant bits to use while encoding
  --use_nth_byte          use only every nth byte (e.g. if 4: 1 byte will be used for data, 3 will be skipped)
  -f, --fill              fill entire file by repeating data
  --profile               profile code (show which parts are taking long)
  -s, --spectrogram       display a spectrogram of the given file
  -p, --play              play the file (if -e provided, it will play after encoding, to hear the noise)

For example to encode the message My secret! in a file called audio.wav:

$ ./stegowav.py audio.wav --encode "My secret!" --output audio_with_secret.wav

Some example 1 second .wav files are provided with keywords which can be used for testing: sine, square, sawtooth and hello. So the above command can use hello like this, instead of audio.wav if you do not have a wav file ready:

$ ./stegowav.py hello --encode "My secret!" --output audio_with_secret.wav

To decode the message from the file add the --decode flag:

$ ./stegowav.py audio_with_secret.wav --decode
Decoded message (len=10):
My secret!

To compare how the audio has changed you can add a --play flag, if combined with the --encode flag it will play the audio file after encoding. Alternatively, a spectrogram can be created with a before and after. For example, here the file is filled with repeating the letter a (--fill flag). By doing this a very clear line can be seen at 12 kHz:

$ ./stegowav.py hello --encode a --fill --spectrogram --lsb 1

This is clearly audible. To avoid such an issue, encryption can be used by adding the --encryption-type 2 flag to randomize the data (1: FERNET, 2: AES, 3: RSA, AES is recommended).

To get an impression of the audibility of encoded messages the degradation_eval.py script located in the evaluation folder can be executed.

$ ./evaluation/degredation_eval.py

This script generates a test case for each of the files located in audio/1_min_files and tasks the user to choose in which file(s) he detects audible degradation. The created test reports are saved in evaluation/eval_reports/.

All generated evaluation reports can be analyzed by executing eval_report_analysis.py located in the evaluation directory.

$ ./evaluation/eval_report_analysis.py

This creates graphs for each of the used samples, which option the users chose for a specific sample, and aggregates if the user was right or wrong with his decision.

It is possible to add redundant bits to an encoded secret message for error correction. Available error correction methods are Hamming and Reed Solomon codes (1 - Hamming, 2 - Reed Solomon). Here is an example for Hamming codes:

$ ./stegowav.py hello --encode "My secret!" -c 1

Be sure to call the same correction method for decoding as well.

$ ./stegowav.py hello --decode -c 1

As a library

Basics:

from wav_steganography.wav_file import WAVFile

wav_file = WAVFile("wav_file_path.wav")
wav_file.encode("My secret message")
wav_file.decode()  # "My secret message"

Encode takes mostly the same parameters as the CLI above, here the default parameters are shown. See the CLI section above for an explanation for each one.

from wav_steganography.wav_file import WAVFile
from security.encryption_provider import EncryptionProvider
from security.enums.encryption_type import EncryptionType

wav_file = WAVFile("wav_file_path.wav")
wav_file.encode(
    "My secret message",
    least_significant_bits=2,
    redundant_bits=0,
    every_nth_byte=1,
    encryptor=EncryptionProvider.get_encryptor(EncryptionType.NONE),  # e.g. for AES: EncryptionType.AES
    repeat_data=False,
)
# To display the spectrogram
wav_file.spectrogram()

# Plays the sound
wav_file.play()

# Writes the possibly encoded wav_file to the given path
wav_file.write("encoded_wav_file_path.wav")

About

This project was created for the Cyber-Security course at the University of Rostock in 2021.