n-digit-token/lib/library/generateWithoutModuloBias.js

Cryptographically secure pseudo-random token of n digits

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.generateWithoutModuloBias = void 0;
const calculateByteSize_1 = require("./calculateByteSize");
const calculateMax_1 = require("./calculateMax");
const generateSecureBytes_1 = require("./generateSecureBytes");
/**
 * Generates a cryptographically secure pseudo random token string of given length.
 * This implementation avoids modulo bias.
 * @param {number} length
 * @param {Options} [options]
 * @return {bigint} token
 */
const generateWithoutModuloBias = (length, options) => {
    const byteSize = (0, calculateByteSize_1.calculateByteSize)(length, options);
    const max = (0, calculateMax_1.calculateMax)({ byteSize, length });
    let secureInt = 0n;
    do {
        secureInt = 0n; // minimize memory usage
        const secureBytes = (0, generateSecureBytes_1.generateSecureBytes)(byteSize, options);
        secureInt = BigInt('0x' + secureBytes);
    } while (secureInt > max);
    return secureInt % BigInt(10n ** BigInt(length));
};
exports.generateWithoutModuloBias = generateWithoutModuloBias;