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Macide Celik 2019-10-29 13:15:34 +03:00 • committed by GitHub
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src/core/operations/ExtractLSB.mjs
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/**
* @author Ge0rg3 [georgeomnet+cyberchef@gmail.com]
* @copyright Crown Copyright 2019
* @license Apache-2.0
*/
import Operation from "../Operation.mjs";
import OperationError from "../errors/OperationError.mjs";
import Utils from "../Utils.mjs";
import { fromBinary } from "../lib/Binary.mjs";
import { isImage } from "../lib/FileType.mjs";
import jimp from "jimp";
/**
* Extract LSB operation
*/
class ExtractLSB extends Operation {
/**
* ExtractLSB constructor
*/
constructor() {
super();
this.name = "Extract LSB";
this.module = "Image";
this.description = "Extracts the Least Significant Bit data from each pixel in an image. This is a common way to hide data in Steganography.";
this.infoURL = "https://wikipedia.org/wiki/Bit_numbering#Least_significant_bit_in_digital_steganography";
this.inputType = "ArrayBuffer";
this.outputType = "byteArray";
this.args = [
{
name: "Colour Pattern #1",
type: "option",
value: COLOUR_OPTIONS,
},
{
name: "Colour Pattern #2",
type: "option",
value: ["", ...COLOUR_OPTIONS],
},
{
name: "Colour Pattern #3",
type: "option",
value: ["", ...COLOUR_OPTIONS],
},
{
name: "Colour Pattern #4",
type: "option",
value: ["", ...COLOUR_OPTIONS],
},
{
name: "Pixel Order",
type: "option",
value: ["Row", "Column"],
},
{
name: "Bit",
type: "number",
value: 0
}
];
}
/**
* @param {ArrayBuffer} input
* @param {Object[]} args
* @returns {byteArray}
*/
async run(input, args) {
if (!isImage(input)) throw new OperationError("Please enter a valid image file.");
const bit = 7 - args.pop(),
pixelOrder = args.pop(),
colours = args.filter(option => option !== "").map(option => COLOUR_OPTIONS.indexOf(option)),
parsedImage = await jimp.read(input),
width = parsedImage.bitmap.width,
height = parsedImage.bitmap.height,
rgba = parsedImage.bitmap.data;
if (bit < 0 || bit > 7) {
throw new OperationError("Error: Bit argument must be between 0 and 7");
}
let i, combinedBinary = "";
if (pixelOrder === "Row") {
for (i = 0; i < rgba.length; i += 4) {
for (const colour of colours) {
combinedBinary += Utils.bin(rgba[i + colour])[bit];
}
}
} else {
let rowWidth;
const pixelWidth = width * 4;
for (let col = 0; col < width; col++) {
for (let row = 0; row < height; row++) {
rowWidth = row * pixelWidth;
for (const colour of colours) {
i = rowWidth + (col + colour * 4);
combinedBinary += Utils.bin(rgba[i])[bit];
}
}
}
}
return fromBinary(combinedBinary);
}
}
const COLOUR_OPTIONS = ["R", "G", "B", "A"];
export default ExtractLSB;