CyberChef/src/core/operations/AESKeyUnwrap.mjs

129 lines
4.3 KiB
JavaScript
Raw Normal View History

/**
* @author mikecat
* @copyright Crown Copyright 2022
* @license Apache-2.0
*/
import Operation from "../Operation.mjs";
import Utils from "../Utils.mjs";
import { toHexFast } from "../lib/Hex.mjs";
import forge from "node-forge";
import OperationError from "../errors/OperationError.mjs";
/**
* AES Key Unwrap operation
*/
class AESKeyUnwrap extends Operation {
/**
* AESKeyUnwrap constructor
*/
constructor() {
super();
this.name = "AES Key Unwrap";
this.module = "Ciphers";
this.description = "Decryptor for a key wrapping algorithm defined in RFC3394, which is used to protect keys in untrusted storage or communications, using AES.<br><br>This algorithm uses an AES key (KEK: key-encryption key) and a 64-bit IV to decrypt 64-bit blocks.";
this.infoURL = "https://wikipedia.org/wiki/Key_wrap";
this.inputType = "string";
this.outputType = "string";
this.args = [
{
"name": "Key (KEK)",
"type": "toggleString",
"value": "",
"toggleValues": ["Hex", "UTF8", "Latin1", "Base64"]
},
{
"name": "IV",
"type": "toggleString",
"value": "a6a6a6a6a6a6a6a6",
"toggleValues": ["Hex", "UTF8", "Latin1", "Base64"]
},
{
"name": "Input",
"type": "option",
"value": ["Hex", "Raw"]
},
{
"name": "Output",
"type": "option",
"value": ["Hex", "Raw"]
},
];
}
/**
* @param {string} input
* @param {Object[]} args
* @returns {string}
*/
run(input, args) {
const kek = Utils.convertToByteString(args[0].string, args[0].option),
iv = Utils.convertToByteString(args[1].string, args[1].option),
inputType = args[2],
outputType = args[3];
if (kek.length !== 16 && kek.length !== 24 && kek.length !== 32) {
throw new OperationError("KEK must be either 16, 24, or 32 bytes (currently " + kek.length + " bytes)");
}
if (iv.length !== 8) {
throw new OperationError("IV must be 8 bytes (currently " + iv.length + " bytes)");
}
const inputData = Utils.convertToByteString(input, inputType);
if (inputData.length % 8 !== 0 || inputData.length < 24) {
throw new OperationError("input must be 8n (n>=3) bytes (currently " + inputData.length + " bytes)");
}
const cipher = forge.cipher.createCipher("AES-ECB", kek);
cipher.start();
cipher.update(forge.util.createBuffer(""));
cipher.finish();
const paddingBlock = cipher.output.getBytes();
const decipher = forge.cipher.createDecipher("AES-ECB", kek);
let A = inputData.substring(0, 8);
const R = [];
for (let i = 8; i < inputData.length; i += 8) {
R.push(inputData.substring(i, i + 8));
}
let cntLower = R.length >>> 0;
let cntUpper = (R.length / ((1 << 30) * 4)) >>> 0;
cntUpper = cntUpper * 6 + ((cntLower * 6 / ((1 << 30) * 4)) >>> 0);
cntLower = cntLower * 6 >>> 0;
for (let j = 5; j >= 0; j--) {
for (let i = R.length - 1; i >= 0; i--) {
const aBuffer = Utils.strToArrayBuffer(A);
const aView = new DataView(aBuffer);
aView.setUint32(0, aView.getUint32(0) ^ cntUpper);
aView.setUint32(4, aView.getUint32(4) ^ cntLower);
A = Utils.arrayBufferToStr(aBuffer, false);
decipher.start();
decipher.update(forge.util.createBuffer(A + R[i] + paddingBlock));
decipher.finish();
const B = decipher.output.getBytes();
A = B.substring(0, 8);
R[i] = B.substring(8, 16);
cntLower--;
if (cntLower < 0) {
cntUpper--;
cntLower = 0xffffffff;
}
}
}
if (A !== iv) {
throw new OperationError("IV mismatch");
}
const P = R.join("");
if (outputType === "Hex") {
return toHexFast(Utils.strToArrayBuffer(P));
}
return P;
}
}
export default AESKeyUnwrap;