cyberchef
Version:
The Cyber Swiss Army Knife for encryption, encoding, compression and data analysis.
165 lines (146 loc) • 5.82 kB
JavaScript
/**
* @author cktgh [chankaitung@gmail.com]
* @copyright Crown Copyright 2026
* @license Apache-2.0
*/
import Operation from "../Operation.mjs";
import OperationError from "../errors/OperationError.mjs";
import forge from "node-forge";
import Utils, { isWorkerEnvironment } from "../Utils.mjs";
import { DELIM_OPTIONS } from "../lib/Delim.mjs";
/**
* Pseudo-Random Integer Generator operation
*/
class PseudoRandomIntegerGenerator extends Operation {
// in theory 2**53 is the max range, but we use Number.MAX_SAFE_INTEGER (2**53 - 1) as it is more consistent.
static MAX_RANGE = Number.MAX_SAFE_INTEGER;
// arbitrary choice
static BUFFER_SIZE = 1024;
/**
* PseudoRandomIntegerGenerator constructor
*/
constructor() {
super();
this.name = "Pseudo-Random Integer Generator";
this.module = "Ciphers";
this.description = "A cryptographically-secure pseudo-random number generator (PRNG).<br><br>Generates random integers within a specified range using the browser's built-in <code>crypto.getRandomValues()</code> method if available.<br><br>The supported range of integers is from <code>-(2^53 - 1)</code> to <code>(2^53 - 1)</code>.";
this.infoURL = "https://wikipedia.org/wiki/Pseudorandom_number_generator";
this.inputType = "string";
this.outputType = "string";
this.args = [
{
"name": "Number of Integers",
"type": "number",
"value": 1,
"min": 1
},
{
"name": "Min Value",
"type": "number",
"value": 0,
"min": Number.MIN_SAFE_INTEGER,
"max": Number.MAX_SAFE_INTEGER
},
{
"name": "Max Value",
"type": "number",
"value": 99,
"min": Number.MIN_SAFE_INTEGER,
"max": Number.MAX_SAFE_INTEGER
},
{
"name": "Delimiter",
"type": "option",
"value": DELIM_OPTIONS
},
{
"name": "Output",
"type": "option",
"value": ["Raw", "Hex", "Decimal"]
}
];
// not using BigUint64Array to avoid BigInt handling overhead
this.randomBuffer = new Uint32Array(PseudoRandomIntegerGenerator.BUFFER_SIZE);
this.randomBufferOffset = PseudoRandomIntegerGenerator.BUFFER_SIZE;
}
/**
* @param {string} input
* @param {Object[]} args
* @returns {string}
*/
run(input, args) {
const [numInts, minInt, maxInt, delimiter, outputType] = args;
if (minInt === null || maxInt === null) return "";
const min = Math.ceil(minInt);
const max = Math.floor(maxInt);
const delim = Utils.charRep(delimiter || "Space");
if (!Number.isSafeInteger(min) || !Number.isSafeInteger(max)) {
throw new OperationError("Min and Max must be between `-(2^53 - 1)` and `2^53 - 1`.");
}
if (min > max) {
throw new OperationError("Min cannot be larger than Max.");
}
const range = max - min + 1; // inclusive range
if (range > PseudoRandomIntegerGenerator.MAX_RANGE) {
throw new OperationError("Range between Min and Max cannot be larger than `2^53`");
}
// as large as possible while divisible by range
const rejectionThreshold = PseudoRandomIntegerGenerator.MAX_RANGE - (PseudoRandomIntegerGenerator.MAX_RANGE % range);
const output = [];
for (let i = 0; i < numInts; i++) {
const result = this._generateRandomValue(rejectionThreshold);
const intValue = min + (result % range);
switch (outputType) {
case "Hex":
output.push(intValue.toString(16));
break;
case "Decimal":
output.push(intValue.toString(10));
break;
case "Raw":
default:
output.push(Utils.chr(intValue));
}
}
if (outputType === "Raw") {
return output.join("");
}
return output.join(delim);
}
/**
* Generate a random value, result will be less than the rejection threshold (exclusive).
*
* @param {number} rejectionThreshold
* @returns {number}
*/
_generateRandomValue(rejectionThreshold) {
let result;
do {
if (this.randomBufferOffset + 2 > this.randomBuffer.length) {
this._resetRandomBuffer();
}
// stitching a 53 bit number; not using BigUint64Array to avoid BigInt handling overhead
result = (this.randomBuffer[this.randomBufferOffset++] & 0x1f_ffff) * 0x1_0000_0000 +
this.randomBuffer[this.randomBufferOffset++];
} while (result >= rejectionThreshold);
return result;
}
/**
* Fill random buffer with new random values and rseet the offset.
*/
_resetRandomBuffer() {
if (isWorkerEnvironment() && self.crypto) {
self.crypto.getRandomValues(this.randomBuffer);
} else {
const bytes = forge.random.getBytesSync(this.randomBuffer.length * 4);
for (let j = 0; j < this.randomBuffer.length; j++) {
this.randomBuffer[j] = (bytes.charCodeAt(j * 4) << 24) |
(bytes.charCodeAt(j * 4 + 1) << 16) |
(bytes.charCodeAt(j * 4 + 2) << 8) |
bytes.charCodeAt(j * 4 + 3);
}
}
this.randomBufferOffset = 0;
}
}
export default PseudoRandomIntegerGenerator;