CPP.ImageEncoder

This program encodes text in a bitmap image (.bmp). It works by using LSB steganography which is the process of modifying the least significant bit of a pixel to store part of a character.

Define application constants

The default values for kHeaderSize, kFooterSize and kMaxSecretLen are 1024. This can be changed with minimal impact on the program

• kHeaderSize The minimum value that I would recommend setting this to would be 256. After a quick look on Wikipedia, it looks like anywhere between 16 and 196 bytes are required for the header. Setting it at 256 or higher seems safe.

• kFooterSize It doesn't look like a bitmap has a footer. This was included for .jpg images. Play around with it if you would like but there is certainly no harm in leaving it at the default value

• kMaxSecretLen This was included to stop the python version crashing. Though it has the added benefit of outputting a reasonable amount of text to the screen. Using larger values will decrease the speed of the program, and increase the amount of text outputted but shouldn't have an adverse effect

• kCleanImageName I've done an MD5 hash of "CLEAN" and appended it to the filename to reduce the chance of overwriting an important file

Functions

Read image file in

FILE* ReadImg(std::string image_name)

Write image file

FILE* WriteImg(std::string image_name)

Get the size of the image in bytes to prevent overwriting footer

int GetSize(std::string image_name)

Replace the least significant bit with a 0

int WriteCleanImg(std::string input_image_name, std::string output_image_name)

Write a secret message to the image

int WriteEncodedImg(std::string input_image_name, std::string output_image_name,
	std::string secret_msg)

Read the encoded image

int ReadEncodedImg(std::string input_image_name)

The CLI

int Cli()

Using the CLI

"Clean, Encode, Clean and Encode (.bmp only), Decode or Quit? (C, e, a, d, q)"

• Entering 'c' will clean an image (specified by its path)
• Entering 'e' will encode an image (specified by its path)
• Entering 'a' will clean and encode an image (specified by its path)
• Entering 'd' will decode an image (specified by its path)
• Entering 'q' will quit the program

"Type the name of the input image (include the file extension and path if required)"

• Enter the path to an input image

"Type the name of the output image (include the file extension and path if required)"

• If the user selected Clean, Encode, or Clean and Encode. Enter the path of an output image

"Type the secret message (max kMaxSecretLen characters)"

• If the user selected Encode, or Clean and Encode. Enter a message for the program to encode in the image

Language information

This program is written in C++ using Visual Studio Community Edition 2017 on Windows 10. To install this IDE, go to https://visualstudio.microsoft.com/

How to run

Method 1

1. Download or clone this GitHub repository
2. (If downloaded) Extract the zip archive
3. Open the project by going to File> Open> Project/Solution
4. Run the program by pressing the green play button or with F5

Method 2

1. Download or clone this GitHub repository
2. (If downloaded) Extract the zip archive
3. Go to bin> Debug
4. Double click the .exe file (note that windows will ask if you want to run the file – only run executables that you trust)

Download

Clone

Using The Command Line

1. Press the Clone or download button in the top right
2. Copy the URL (link)
3. Open the command line and change directory to where you wish to clone to
4. Type 'git clone' followed by URL in step 2

$ git clone https://github.com/FredHappyface/CPP.ImageEncoder

More information can be found at https://help.github.com/en/articles/cloning-a-repository

Using GitHub Desktop

1. Press the Clone or download button in the top right
2. Click open in desktop
3. Choose the path for where you want and click Clone

More information can be found at https://help.github.com/en/desktop/contributing-to-projects/cloning-a-repository-from-github-to-github-desktop

Download Zip File

1. Download this GitHub repository
2. Extract the zip archive
3. Copy/ move to the desired location

Licence

MIT License Copyright (c) FredHappyface (See the LICENSE for more information.)