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