Pridestalkerr / bmp-encryption

Symmetric-key BMP image encryption algorithm.

bmp-encryption

Symmetric-key BMP image encryption algorithm. Also performs a chitest for both input and output and prints it to the console.

INSTALLATION

gcc -o executable app.c

USAGE

./executable [enc/dec] [sourcePath] [destinationPath] [keyPath]

enc - encode file
dec - decode file
sourcePath - path to image
destinationPath - path to output
keyPath - path to key.txt (must contain 2 unsigned 32bit integers separated by a space)

EXAMPLE

doge:

doge after encryption:

./a.out enc doge.bmp dogeEnc.bmp key.txt 
before: R: 1049538.812233 G: 739433.472262 B: 374238.833570
after: R: 272.435277 G: 261.401138 B: 233.044097

doge after decryption:

./a.out dec dogeEnc.bmp dogeDec.bmp key.txt 
before: R: 272.435277 G: 261.401138 B: 233.044097
after: R: 1049538.812233 G: 739433.472262 B: 374238.833570

HOW IT WORKS

This algorithm only encrypts the pixels of an image, leaving everything else unchanged.

• First, a permutation is generated using the Fisher-Yates Shuffle using multiple xorshifts on keyR; after which the pixels are then permuted according to it.
• The pixels are then recursively encoded using keyR and keySV as seeds for differend operations.
• Decryption is achieved using the above steps in reverse.

One might wonder: Why in the world would you only encrypt the pixels and not the whole image, maybe even bit by bit?
Good question...