Bit Plane Browser and LSB Extraction

Bit Plane Browser and LSB Extraction

Bit Plane Browser and LSB Extraction

src/core/operations/ViewBitPlane.mjs

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+/**
+ * @author Ge0rg3 [georgeomnet+cyberchef@gmail.com]
+ * @copyright Crown Copyright 2019
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import OperationError from "../errors/OperationError";
+import Utils from "../Utils";
+import { isImage } from "../lib/FileType";
+import { toBase64 } from "../lib/Base64";
+import jimp from "jimp";
+
+/**
+ * View Bit Plane operation
+ */
+class ViewBitPlane extends Operation {
+
+    /**
+     * ViewBitPlane constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "View Bit Plane";
+        this.module = "Image";
+        this.description = "Extracts and displays a bit plane of any given image. These show only a single bit from each pixel, and so are often used to hide messages in Steganography.";
+        this.infoURL = "https://wikipedia.org/wiki/Bit_plane";
+        this.inputType = "byteArray";
+        this.outputType = "byteArray";
+        this.presentType = "html";
+        this.args = [
+            {
+                name: "Colour",
+                type: "option",
+                value: COLOUR_OPTIONS
+            },
+            {
+                name: "Bit",
+                type: "number",
+                value: 0
+            }
+        ];
+    }
+
+    /**
+     * @param {File} input
+     * @param {Object[]} args
+     * @returns {File}
+     */
+    async run(input, args) {
+        if (!isImage(input)) throw new OperationError("Please enter a valid image file.");
+
+        const [colour, bit] = args,
+            parsedImage = await jimp.read(Buffer.from(input)),
+            width = parsedImage.bitmap.width,
+            height = parsedImage.bitmap.height,
+            colourIndex = COLOUR_OPTIONS.indexOf(colour),
+            bitIndex = 7-bit;
+
+        if (bit < 0 || bit > 7) {
+            throw new OperationError("Error: Bit argument must be between 0 and 7");
+        }
+
+        parsedImage.rgba(true);
+
+        let pixel, bin, newPixelValue;
+
+        parsedImage.scan(0, 0, width, height, function(x, y, idx) {
+            pixel = this.bitmap.data[idx + colourIndex];
+            bin = Utils.bin(pixel);
+            newPixelValue = 255;
+
+            if (bin.charAt(bitIndex) === "1") newPixelValue = 0;
+
+            for (let i=0; i < 4; i++) {
+                this.bitmap.data[idx + i] = newPixelValue;
+            }
+        });
+
+        const imageBuffer = await parsedImage.getBufferAsync(jimp.AUTO);
+
+        return Array.from(imageBuffer);
+    }
+
+    /**
+     * Displays the extracted data as an image for web apps.
+     * @param {byteArray} data
+     * @returns {html}
+     */
+    present(data) {
+        if (!data.length) return "";
+        const type = isImage(data);
+
+        return `<img src="data:${type};base64,${toBase64(data)}">`;
+    }
+
+}
+
+const COLOUR_OPTIONS = [
+    "Red",
+    "Green",
+    "Blue",
+    "Alpha"
+];
+
+export default ViewBitPlane;