gen-totp
Version:
A time-based One-time Password generator that uses current time as a source of uniqueness, following RFC 6238.
102 lines (101 loc) • 3.88 kB
JavaScript
;
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.genTOTP = exports.decToHex = exports.hexToDec = exports.base32ToHex = exports.leftPad = void 0;
var jssha_1 = __importDefault(require("jssha"));
/**
* Left pads a string to a specified length.
* @param {string} str - The string to pad.
* @param {number} len - The desired length.
* @param {string} pad - The padding character.
* @returns {string} The padded string.
*/
function leftPad(str, len, pad) {
return str.length >= len ? str : pad.repeat(len - str.length) + str;
}
exports.leftPad = leftPad;
/**
* Decodes a base32-encoded string to hexadecimal.
* Supports RFC 4648 Base32.
* @param {string} input - The base32 string.
* @returns {string} The decoded hexadecimal string.
*/
function base32ToHex(input) {
var base32Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
var cleanInput = input.toUpperCase().replace(/=+$/, "");
var bits = "";
var hex = "";
for (var _i = 0, cleanInput_1 = cleanInput; _i < cleanInput_1.length; _i++) {
var char = cleanInput_1[_i];
var val = base32Chars.indexOf(char);
if (val === -1) {
throw new Error("Invalid base32 character: ".concat(char));
}
bits += leftPad(val.toString(2), 5, "0");
}
for (var i = 0; i + 4 <= bits.length; i += 4) {
var chunk = bits.slice(i, i + 4);
hex += parseInt(chunk, 2).toString(16);
}
return hex;
}
exports.base32ToHex = base32ToHex;
/**
* Converts a hexadecimal string to a decimal number.
* @param {string} hex - The hexadecimal string.
* @returns {number} The decimal number.
*/
function hexToDec(hex) {
return parseInt(hex, 16);
}
exports.hexToDec = hexToDec;
/**
* Converts a decimal number to a hexadecimal string.
* @param {number} dec - The decimal number.
* @returns {string} The hexadecimal string.
*/
function decToHex(dec) {
return leftPad(Math.round(dec).toString(16), 2, "0");
}
exports.decToHex = decToHex;
/**
* Generates a TOTP (Time-based One-Time Password).
* @param {string} key - The secret key.
* @param {GenTOTPOptions} [options={}] - Configuration options.
* @param {number} [options.period=30] - Time period in seconds.
* @param {string} [options.algorithm='SHA-1'] - Hash algorithm.
* @param {number} [options.digits=6] - Length of the resulting OTP.
* @param {KeyEncoding} [options.encoding='utf8'] - Encoding of the key ('utf8', 'hex', or 'base32').
* @returns {string} The generated OTP.
*/
function genTOTP(key, options) {
if (options === void 0) { options = {}; }
var _a = options.period, period = _a === void 0 ? 30 : _a, _b = options.algorithm, algorithm = _b === void 0 ? "SHA-1" : _b, _c = options.digits, digits = _c === void 0 ? 6 : _c, _d = options.encoding, encoding = _d === void 0 ? "utf8" : _d;
var epoch = Math.floor(Date.now() / 1000);
var timeHex = leftPad(decToHex(Math.floor(epoch / period)), 16, "0");
var hexKey;
if (encoding === "hex") {
hexKey = key.toLowerCase();
}
else if (encoding === "base32") {
hexKey = base32ToHex(key);
}
else {
// utf8 to hex
var encoder = new TextEncoder();
hexKey = Array.from(encoder.encode(key))
.map(function (b) { return b.toString(16).padStart(2, "0"); })
.join("");
}
var shaObj = new jssha_1.default(algorithm, "HEX");
shaObj.setHMACKey(hexKey, "HEX");
shaObj.update(timeHex);
var hmac = shaObj.getHMAC("HEX");
var offset = hexToDec(hmac[hmac.length - 1]);
var code = (hexToDec(hmac.slice(offset * 2, offset * 2 + 8)) & 0x7fffffff).toString();
return code.slice(-digits);
}
exports.genTOTP = genTOTP;
exports.default = genTOTP;