mirror of https://github.com/gchq/CyberChef.git
125 lines
3.3 KiB
JavaScript
125 lines
3.3 KiB
JavaScript
/**
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* @author Matt C [matt@artemisbot.uk]
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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";
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import { genPolybiusSquare } from "../lib/Ciphers";
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import OperationError from "../errors/OperationError";
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/**
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* Bifid Cipher Decode operation
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*/
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class BifidCipherDecode extends Operation {
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/**
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* BifidCipherDecode constructor
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*/
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constructor() {
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super();
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this.name = "Bifid Cipher Decode";
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this.module = "Ciphers";
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this.description = "The Bifid cipher is a cipher which uses a Polybius square in conjunction with transposition, which can be fairly difficult to decipher without knowing the alphabet keyword.";
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this.inputType = "string";
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this.outputType = "string";
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this.args = [
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{
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"name": "Keyword",
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"type": "string",
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"value": ""
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}
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];
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}
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/**
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* @param {string} input
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* @param {Object[]} args
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* @returns {string}
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*
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* @throws {OperationError} if invalid key
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*/
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run(input, args) {
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const keywordStr = args[0].toUpperCase().replace("J", "I"),
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keyword = keywordStr.split("").unique(),
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alpha = "ABCDEFGHIKLMNOPQRSTUVWXYZ",
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structure = [];
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let output = "",
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count = 0,
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trans = "";
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if (!/^[A-Z]+$/.test(keywordStr) && keyword.length > 0)
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throw new OperationError("The key must consist only of letters in the English alphabet");
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const polybius = genPolybiusSquare(keywordStr);
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input.replace("J", "I").split("").forEach((letter) => {
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const alpInd = alpha.split("").indexOf(letter.toLocaleUpperCase()) >= 0;
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let polInd;
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if (alpInd) {
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for (let i = 0; i < 5; i++) {
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polInd = polybius[i].indexOf(letter.toLocaleUpperCase());
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if (polInd >= 0) {
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trans += `${i}${polInd}`;
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}
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}
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if (alpha.split("").indexOf(letter) >= 0) {
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structure.push(true);
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} else if (alpInd) {
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structure.push(false);
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}
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} else {
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structure.push(letter);
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}
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});
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structure.forEach(pos => {
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if (typeof pos === "boolean") {
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const coords = [trans[count], trans[count+trans.length/2]];
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output += pos ?
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polybius[coords[0]][coords[1]] :
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polybius[coords[0]][coords[1]].toLocaleLowerCase();
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count++;
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} else {
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output += pos;
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}
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});
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return output;
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}
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/**
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* Highlight Bifid Cipher Decode
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*
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* @param {Object[]} pos
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* @param {number} pos[].start
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* @param {number} pos[].end
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* @param {Object[]} args
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* @returns {Object[]} pos
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*/
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highlight(pos, args) {
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return pos;
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}
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/**
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* Highlight Bifid Cipher Decode in reverse
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*
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* @param {Object[]} pos
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* @param {number} pos[].start
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* @param {number} pos[].end
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* @param {Object[]} args
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* @returns {Object[]} pos
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*/
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highlightReverse(pos, args) {
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return pos;
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}
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}
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export default BifidCipherDecode;
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