IMJA

Stegonagraphy - encrypting a hidden text message in an image

Using a SHA512 hash, Imja (IMage ninJA) will encode a secret message across the three two least significant bits of an images 'RGB' color channels, pixel by pixel.

After modifying an image with your hidden message, the image is returned to the user, visibly unchanged.

Send your modified image to a friend. Only by entering the same 'password' can the hidden message be revealed.

Use IMJA to hide copyright information. Or to send Memes with secret plans!

Version History:

• V1.4

  • Images of type 'P' (Palatted) are converted to RGB when Encoding
  • non-RGB images are converted to RGB when Decoding to prevent crashes
  • Live demo updated on Heroku from V1.1 to V1.4

• V1.3

  • Hash changed to no longer combine hex values (0-15)
  • Uses a modified algo to only modify the 2 least significant bits of an image
  • Images created prior to V1.3 can not be decoded in V1.3+
  • Increased font fidelity by storing 8 shades of grey in the least sig bit
  • JS front-end to allow for dynamic text box for user input
  • Deprecates fixed font size, imported font, and word wrap
  • On image load, displays the file dimensions & adjusts the drawable text area
  • Dockerized deployment taken offline as version was outdated

• V1.2

  • Dockerized and Deployed

• V1.1

  • Restructured files/folders to deploy on Heroku
  • Refactord a new route with a long single function to prevent issues on Heroku

• V1.0

  • Takes in user input, Uses a monospaced font to fill in image area adding linebreaks as needed
  • Creates a hash from a password adding two hex values (0 - 511)
  • Encodes image using 3 least sig bits of 3 color channels = 9 bits
  • Uses Flask to create Front-end HTML

Confidentiality by using a data URI

Imja outputs images using an embedded URI. Nothing is saved to disk or stored server side

• URI wiki: https://en.wikipedia.org/wiki/Data_URI_scheme
• A Data URI consists of: data:[<media type>][;base64],<data>

Limitations

• Rich text, HTML, and other code is not supported in the message. Any/All Special characters will appear as text

• IMJA supports only .png images without transparency

• 'RGBA' images will be converted to 'RGB'

• Modifying an image after it has been encoded will compromise the hidden message quality

• Images of any size are supported up to the URI character length of ~2,083 (browser limitation)

• Encoded text is fixed at 7px x 13px per character

• A message greater then the image width will be auto-wrapped by character

• A message greater then the available image size will have visible clipping with a detailed warning of the character limit

• Zooming into a decoded image is recommended to read the text

• URI's are not supported at the base level on some browzers. Opening an image in another tab may cause an error

• Encoding/Decoding a message with no image attached will result in an unhandled exception (browser error)

DEMO

Imja is deployed on Heroku and free to use https://imja.herokuapp.com/

The Dockerized version is deployed at https://imja.dev.genji.games/

What's inside:

• Flask - Backend https://flask.palletsprojects.com/en/1.1.x/

• PIL - Pillow - Python Imaging Library https://pillow.readthedocs.io/en/stable/

• Hashlib - Secure hashes and message digests https://docs.python.org/3/library/hashlib.html

• Base64 - binary-to-text encoding https://en.wikipedia.org/wiki/Base64

• BytesIO - produces bytes objects https://docs.python.org/3/library/io.html

• re - Regex https://docs.python.org/3/library/re.html

• Fabric.js - front end & textbox http://fabricjs.com

Licensing

No license is granted

Contact information

Genji.Tapia@students.makeschool.com