File Injector

If you want to use a previous version (1.0.2 or lower), where you needed the original image to extract the file, you can download it here.

Index

• 1. Description
• 2. Getting Started
  • Install requirements
  • Run the script
  • Choose input
    • Choose a base image/audio
    • Choose an input file
    • Choose/Generate an encryption key
• 3. Results
• 4. Examples of use
  • Injection
  • Extraction
• 5. Configuration
• 6. What it does
• 7. How it works
  • Options
  • inject_file_func
  • extract_file_func
  • get_fernet
  • decrypt_content
  • inject_file
  • extract_file

1. Description

File Injector is a script that allows you to store any file (.zip, .png, .txt, .gba...) and its filename in an image/audio as noise, using steganography.

You can also choose to encrypt the input file before storing it.

Then, to extract the file from the modified image/audio, you DON'T need the original image/audio, just the encryption key if the file has been encrypted.

2. Getting Started

Install Requirements

python3 -m pip install -r requirements.txt

If that doesn't work, you can try:

py -m pip install -r requirements.txt

Run the script

python3 main.py

Choose input

Choose a base image/audio

Choose a base image/audio for storing the file from the files/base folder.

You can also add your own images/audios to this folder.

• The images can be .png or (.jpg/.jpeg), but they will be converted to .png when the script is run.
• The audios have to be .mp3 or .wav, but they will be converted to .mp3 when the script is run.

Choose an input file

Choose a file to be stored in the image/audio from the files/input folder.

You can add your own files to this folder. They can be any type of files.

Choose a modified image/audio

Choose a modified image/audio for extracting the file from the files/modified folder.

You can also add your own modified images/audios to this folder.

Choose/Generate an encryption key

You can choose a key from the files/$encryption-keys folder or generate one there.

The key file must have the .key extension

You don't need to choose a particular one when decrypting a file, it will be selected automatically from the folder.

3. Results

This 17.1MP image contains an encrypted 9MB .zip file and its filename stored as noise.

<img src="https://raw.githubusercontent.com/carlospuenteg/file-injector/main/readme-assets/17"1MP_mod.png" width=500>

This 1.7MP image contains an encrypted 0.93MB .zip file and its filename stored as noise.

<img src="https://raw.githubusercontent.com/carlospuenteg/file-injector/main/readme-assets/1"7MP_mod.png" width=500>

This 42MB audio file contains an encrypted 9MB .zip file and its filename stored as noise.

https://user-images.githubusercontent.com/65092569/202014519-24514110-4bd2-4c2b-9307-237964df0c2b.mp4

4. Examples of use

Injection

... File-Injector % python3 main.py
[0] EXIT
[1] Inject file
[2] Extract file

Option: 1
File to be stored: images.zip
Filename of the base image: 2'2MP
Encrypt the file? (y/n): y

Do you want to use an existing key or generate a new one?
[0] Existing key
[1] New key

Option: 1
Filename of the new key file (blank for default): 
Key generated and saved to files/$encryption-keys/key9.key

Preparing...

Modified bits per channel: 2
Image modification: 1.56%

✅ Storing... ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ [100.0%]

Generating random values...

Storing random values...

Reshaping...

Modified image saved in files/modified-images/2'2MP_mod.png

Done in 7.5892 seconds

Extraction

... File-Injector % python3 main.py
[0] EXIT
[1] Inject file
[2] Extract file

Option: 2
Filename of the modified image: 2'2MP_mod

Preparing...

Retrieving filename...

Retrieving input file...
Decrypted with "files/$encryption-keys/key2.key"

Output file saved in files/output-files/images.zip

Done in 1.4083 seconds

5. Configuration

You can change the configuration in the config.py file.

6. What it does

The injection is done by storing the file in the X less significant bits of each element of the array created by flattening the array of image/audio.

• Each element has 8 bits (if the base file is an image) or 16 bits (if the base file is an audio)
• This script changes from 1 to all the bits of each element, depending on the size of the file to be stored compared to the base image/audio.
• If you store a bigger file or if the base image/audio is smaller, more bits will be changed and the changes will be more noticeable.
• If you store a smaller file or if the base image/audio is bigger, less bits will be changed and the changes will be less noticeable.
• If the base image/audio is too small to store the file, the script will stop and warn you.
• If you choose to encrypt the file, its size will increase by ≈1/3.

7. How it works

Options

inject_file_func()

1. If TEST_MODE == True, it will use the predefined base image/audio and input file. Otherwise, it will ask for the base image/audio and input file.
2. Read the file (in bytes)
3. Read the image/audio and store it in a numpy array
4. Read the filename (in bytes)
5. If the user wants to encrypt the file:
   1. Get the key with get_fernet()
   2. Encrypt the file and filename
6. Try to inject the file and filename in the image/audio with inject_file().
   1. If the image/audio is too small to store the file, raise an error
   2. Else, return the modified image/audio.
7. Save the modified image/audio

extract_file_func()

1. If TEST_MODE == True, it will use the predefined modified image/audio. Otherwise, it will ask for the modified image/audio.
2. Read the modified image/audio
3. Extract file and filename as bytes with extract_file()
4. If the file and filename have been encrypted (they start with gAAAAA), decrypt them with decrypt_content
5. Decode the filename to UTF-8
6. Save the file with the decoded filename

get_fernet()

[0] Existing key

1. Choose a key to use from the files/$encryption-keys folder

[1] New key

1. Choose a filename for the new key (or leave it blank for the default one (e.g. key8.key))
2. Generate a new key and save it with the chosen filename
3. Return the Fernet object with the new key

decrypt_content()

1. For each key in the files/$encryption-keys folder:
   1. Try to decrypt the file and filename with it
   2. If InvalidToken is raised:
      1. It means that the key is not the right one
      2. Try with other key
   3. Else, return the key
2. If no key is found, raise an Exception

inject_file()

Returns the modified image/audio array (np.ndarray, with same shape as arr)

extract_file()

Returns a dictionary with the extracted file and filename, both in (bytes) format