111 lines
4.3 KiB
JavaScript
111 lines
4.3 KiB
JavaScript
/**
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* @author Medjedtxm
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* @copyright Crown Copyright 2026
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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 Utils from "../Utils.mjs";
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import OperationError from "../errors/OperationError.mjs";
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import { toHex } from "../lib/Hex.mjs";
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import { decryptXTEA, TEA_BLOCK_SIZE } from "../lib/TEA.mjs";
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/**
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* XTEA Decrypt operation
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*/
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class XTEADecrypt extends Operation {
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/**
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* XTEADecrypt constructor
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*/
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constructor() {
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super();
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this.name = "XTEA Decrypt";
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this.module = "Ciphers";
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this.description = "XTEA (eXtended Tiny Encryption Algorithm) is a block cipher designed by David Wheeler and Roger Needham in 1997 as a successor to TEA, correcting several weaknesses identified in the original algorithm. It operates on 64-bit blocks using a 128-bit key with an improved key schedule that uses sum-dependent key word selection to resist related-key attacks.<br><br>XTEA retains the simplicity and compact implementation of TEA whilst providing significantly improved security. It is frequently encountered in malware analysis and CTF challenges due to its straightforward implementation.<br><br><b>Key:</b> Must be exactly 16 bytes (128 bits).<br><br><b>IV:</b> The Initialisation Vector should be 8 bytes (64 bits). If not entered, it will default to null bytes.<br><br><b>Rounds:</b> The recommended number of rounds is 32 (default). The reference implementation by Wheeler & Needham accepts a configurable round count.<br><br><b>Padding:</b> In CBC and ECB mode, the PKCS#5 padding scheme is used.";
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this.infoURL = "https://wikipedia.org/wiki/XTEA";
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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": "Key",
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"type": "toggleString",
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"value": "",
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"toggleValues": ["Hex", "UTF8", "Latin1", "Base64"]
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},
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{
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"name": "IV",
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"type": "toggleString",
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"value": "",
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"toggleValues": ["Hex", "UTF8", "Latin1", "Base64"]
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},
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{
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"name": "Mode",
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"type": "option",
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"value": ["CBC", "CFB", "OFB", "CTR", "ECB"]
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},
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{
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"name": "Input",
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"type": "option",
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"value": ["Hex", "Raw"]
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},
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{
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"name": "Output",
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"type": "option",
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"value": ["Raw", "Hex"]
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},
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{
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"name": "Padding",
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"type": "option",
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"value": ["PKCS5", "NO", "ZERO", "RANDOM", "BIT"]
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},
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{
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"name": "Rounds",
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"type": "number",
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"value": 32,
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"min": 1,
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"max": 255
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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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run(input, args) {
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const key = Utils.convertToByteArray(args[0].string, args[0].option),
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iv = Utils.convertToByteArray(args[1].string, args[1].option),
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[,, mode, inputType, outputType, padding, rounds] = args;
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if (key.length !== 16)
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throw new OperationError(`Invalid key length: ${key.length} bytes
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XTEA requires a key length of 16 bytes (128 bits).
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Make sure you have specified the type correctly (e.g. Hex vs UTF8).`);
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if (iv.length !== TEA_BLOCK_SIZE && iv.length !== 0 && mode !== "ECB")
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throw new OperationError(`Invalid IV length: ${iv.length} bytes
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XTEA uses an IV length of ${TEA_BLOCK_SIZE} bytes (${TEA_BLOCK_SIZE * 8} bits).
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Make sure you have specified the type correctly (e.g. Hex vs UTF8).`);
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if (!Number.isInteger(rounds) || rounds < 1 || rounds > 255)
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throw new OperationError(`Invalid number of rounds: ${rounds}
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Rounds must be an integer between 1 and 255. Standard XTEA uses 32 rounds.`);
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// Default IV to null bytes if empty (like AES)
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const actualIv = iv.length === 0 ? new Array(TEA_BLOCK_SIZE).fill(0) : iv;
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input = Utils.convertToByteArray(input, inputType);
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const output = decryptXTEA(input, key, actualIv, mode, padding, rounds);
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return outputType === "Hex" ? toHex(output, "") : Utils.byteArrayToUtf8(output);
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}
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}
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export default XTEADecrypt;
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