one-time-pad-image-example.fs

open System
open System.Drawing

let getImage path = 
    let image = Image.FromFile path :?> Bitmap
    Array2D.init image.Width image.Height (fun w h -> image.GetPixel(w,h))

let saveImage path (a:Color[,]) =
    let w = a.GetLength 0
    let h = a.GetLength 1
    use b = new Bitmap(w, h)
    
    Array2D.iteri (fun w h color -> b.SetPixel(w,h,color)) a
    b.Save path

let generateImage width height =
    let rnd = Random()
    let getRandomPixel _ _ =
        Color.FromArgb(rnd.Next 255, rnd.Next 255, rnd.Next 255)
    Array2D.init width height getRandomPixel

let imageXor (a:Color [,]) (b:Color [,]) = 
    let colorXor (a:Color) (b:Color) =
        Color.FromArgb(int a.R ^^^ int  b.R, int a.G ^^^ int b.G, int a.B ^^^ int b.B)

    let w = a.GetLength 0
    let h = a.GetLength 1
    Array2D.init w h (fun w h -> colorXor a.[w,h] b.[w,h])

let a = getImage "c:/tmp/a.bmp"
let b = getImage "c:/tmp/b.bmp"
let randomImage = generateImage (a.GetLength 0) (a.GetLength 1)

let aXored = imageXor a randomImage
let bXored = imageXor b randomImage
saveImage "c:/tmp/a-xored.bmp" aXored
saveImage "c:/tmp/b-xored.bmp" bXored
saveImage "c:/tmp/a-xored-xored.bmp" (aXored|> imageXor randomImage)
saveImage "c:/tmp/b-xored-xored.bmp" (bXored|> imageXor randomImage)
saveImage "c:/tmp/a-xored-b-xored.bmp" (imageXor aXored bXored)