trng-crypto

A small TypeScript/Node.js utility that generates a cryptographically secure random integer with a specific digit length.

Features

• Uses Node's crypto.randomBytes() for secure randomness.
• Avoids modulo bias via rejection sampling.
• Returns bigint by default, or a decimal string with { type: 'string' }.

Install

npm i trng-crypto

getRandomInt(desiredOutputLength: number, options?: { type?: 'string' | 'bigint' }): bigint | string

Generates a random integer with exactly desiredOutputLength decimal digits (desiredOutputLength = 1 may return 0–9).

Optional second argument: pass { type: 'string' } for a decimal string, or { type: 'bigint' } / omit options for a bigint. Default output is bigint.

• desiredOutputLength must be an integer and at least 1.

Throws:

• TypeError if desiredOutputLength is not an integer.
• RangeError if desiredOutputLength < 1.
• TypeError if options.type is present but not "string" or "bigint" (e.g. from plain JavaScript).

Usage

import { getRandomInt } from 'trng-crypto';

const oneDigit = getRandomInt(1); // 0n to 9n
const sixDigits = getRandomInt(6); // 100000n to 999999n
const asString = getRandomInt(6, { type: 'string' }); // '100000' to '999999'

console.log(oneDigit, sixDigits, asString); // 3n 993284n '276402'

const { getRandomInt } = require('trng-crypto');

const oneDigit = getRandomInt(1); // 0n to 9n
const sixDigits = getRandomInt(6); // 100000n to 999999n
const asString = getRandomInt(6, { type: 'string' }); // '100000' to '999999'

console.log(oneDigit, sixDigits, asString); // 8 403709 '855681'

Notes

• Project output is configured to compile from src to dual outputs in dist/cjs and dist/esm.