mirror of https://github.com/gchq/CyberChef.git
95 lines
3.3 KiB
JavaScript
95 lines
3.3 KiB
JavaScript
/**
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* @author PenguinGeorge [george@penguingeorge.com]
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* @copyright Crown Copyright 2018
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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 {alphabetName, ALPHABET_OPTIONS} from "../lib/Base85.mjs";
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/**
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* To Base85 operation
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*/
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class ToBase85 extends Operation {
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/**
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* To Base85 constructor
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*/
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constructor() {
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super();
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this.name = "To Base85";
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this.module = "Default";
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this.description = "Base85 (also called Ascii85) is a notation for encoding arbitrary byte data. It is usually more efficient that Base64.<br><br>This operation encodes data in an ASCII string (with an alphabet of your choosing, presets included).<br><br>e.g. <code>hello world</code> becomes <code>BOu!rD]j7BEbo7</code><br><br>Base85 is commonly used in Adobe's PostScript and PDF file formats.<br><br><strong>Options</strong><br><u>Alphabet</u><ul><li>Standard - The standard alphabet, referred to as Ascii85</li><li>Z85 (ZeroMQ) - A string-safe variant of Base85, which avoids quote marks and backslash characters</li><li>IPv6 - A variant of Base85 suitable for encoding IPv6 addresses (RFC 1924)</li></ul><u>Include delimiter</u><br>Adds a '<~' and '~>' delimiter to the start and end of the data. This is standard for Adobe's implementation of Base85.";
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this.infoURL = "https://wikipedia.org/wiki/Ascii85";
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this.inputType = "ArrayBuffer";
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this.outputType = "string";
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this.args = [
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{
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name: "Alphabet",
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type: "editableOption",
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value: ALPHABET_OPTIONS
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},
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{
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name: "Include delimeter",
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type: "boolean",
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value: false
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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 {string}
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*/
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run(input, args) {
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input = new Uint8Array(input);
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const alphabet = Utils.expandAlphRange(args[0]).join(""),
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encoding = alphabetName(alphabet),
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includeDelim = args[1];
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let result = "";
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if (alphabet.length !== 85 ||
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[].unique.call(alphabet).length !== 85) {
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throw new OperationError("Error: Alphabet must be of length 85");
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}
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if (input.length === 0) return "";
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let block;
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for (let i = 0; i < input.length; i += 4) {
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block = (
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((input[i]) << 24) +
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((input[i + 1] || 0) << 16) +
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((input[i + 2] || 0) << 8) +
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((input[i + 3] || 0))
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) >>> 0;
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if (encoding !== "Standard" || block > 0) {
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let digits = [];
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for (let j = 0; j < 5; j++) {
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digits.push(block % 85);
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block = Math.floor(block / 85);
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}
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digits = digits.reverse();
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if (input.length < i + 4) {
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digits.splice(input.length - (i + 4), 4);
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}
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result += digits.map(digit => alphabet[digit]).join("");
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} else {
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result += (encoding === "Standard") ? "z" : null;
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}
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}
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return includeDelim ? `<~${result}~>` : result;
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}
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}
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export default ToBase85;
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