adrianbiro / File-Injector

File Injector is a script that allows you to store any file in an image using steganography

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
    • 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 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, you DON'T need the original image, 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

Choose a base image for storing/retrieving the file from the files/base-images folder.

You can add your own images to this folder. They can be .png or (.jpg/.jpeg), but they will be converted to .png when the script is run.

Choose an input file

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

You can add your own files to this folder. It can be any file type.

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.

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

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.

Constant	Description	Default value
MOD_PREFIX	Prefix the modified image will have	""
MOD_SUFFIX	Suffix the modified image will have	"_mod"
STORE_RANDOM	Store random data in the modified image so that the limit between the part with the stored data and the part without is not so obvious	True
TEST_MODE	Enables/Disables Test Mode: Test with predefined images and files	True

6. What it does

The injection is done by storing the information in the X less significant bits of the image's channels

• Each channel (R, G and B) has 8 bits, and this script changes from 1 to 4 bits of each channel, depending on the size of the file to be stored.
• If you store a bigger file, more bits will be changed and the changes will be more noticeable.
• If you store a smaller file, less bits will be changed and the changes will be less noticeable.
• If you choose to encrypt the file, its size will increase by ≈1/3.

Changed bits	Image size (MP)	≈Max file size (MB)
1	1	0.375
2	1	0.5
3	1	0.75
4	1	1.5

7. How it works

Options

Option	Description
[0] EXIT	Exit the script
[1] Inject file	Calls inject_file_func()
[2] Extract file	Calls extract_file_func()

inject_file_func()

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

extract_file_func()

1. If TEST_MODE == True, it will use the predefined modified image. Otherwise, it will ask for the modified image.
2. Flatten the modified image
3. Extract the hexadecimal file and filename 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()

Option	Description
[0] Existing key	Use an existing key
[1] New key	Generate a new key

[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()

Parameter	Type	Description
img_arr	np.ndarray	Image as a numpy array
file	str	File in hexadecimal
filename	str	Filename in hexadecimal
store_random	boolean	Whether or not to store random data in the modified image

returns the modified image array (not flattened np.ndarray)

extract_file()

Parameter	Type	Description
mod_img_arr_flat	np.ndarray	Flattened modified image

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