@sourceregistry/node-totp

A zero-dependency, RFC-compliant TOTP (Time-based One-Time Password) library for Node.js. It is intended for server-side 2FA flows with Google Authenticator, Authy, and other TOTP-compatible apps.

• RFC 6238 and RFC 4226 compliant
• Zero external dependencies
• Timing attack resistant token comparison
• TypeScript definitions included
• Tested against RFC vectors
• Strict input validation and safe defaults

Installation

npm install @sourceregistry/node-totp
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Usage

Basic Example

import { generateURI, verifyToken } from '@sourceregistry/node-totp';

// Generate setup URI for authenticator apps
const { uri, secret } = generateURI({
  issuer: 'MyApp',
  account: 'user@example.com',
  algorithm: 'SHA256',
  digits: 6,
  period: 30
});

console.log('Scan this URI in your authenticator app:', uri);
// otpauth://totp/MyApp:user%40example.com?issuer=MyApp&secret=...

// Later, verify user input
const userInput = '123456';
const isValid = verifyToken(userInput, secret, {
  algorithm: 'SHA256',
  digits: 6,
  period: 30,
  window: 1 // Accept tokens from +/-30 seconds
});

console.log('Token valid:', isValid);
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Advanced Configuration

import totp from '@sourceregistry/node-totp';

// Generate with custom secret length (algorithm-appropriate defaults)
const { secret } = totp.generateURI({
  issuer: 'SecureApp',
  account: 'admin@secureapp.com',
  algorithm: 'SHA512', // Uses 64-byte secret by default
  byteLength: 48 // Override default secret length
});

// Verify with custom time (useful for testing)
const testTime = Math.floor(Date.now() / 1000);
const testToken = totp.generateToken(
  totp.base32.decode(secret),
  Math.floor(testTime / 30),
  6,
  'SHA512'
);

const isValid = totp.verifyToken(testToken, secret, {
  algorithm: 'SHA512',
  digits: 6,
  period: 30,
  window: 2,
  now: testTime // Use specific timestamp instead of Date.now()
});
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API Reference

generateURI(options)

Generates an otpauth:// URI and a secret for TOTP setup.

• issuer (string, required): Service name such as MyApp
• account (string, required): User identifier such as an email address
• secret (string, optional): Canonical unpadded Base32 secret
• algorithm (string, optional): SHA1, SHA256, or SHA512 (default SHA1)
• digits (number, optional): 6, 7, or 8 (default 6)
• period (number, optional): Time step in seconds (default 30)
• byteLength (number, optional): Secret length in bytes

Returns { uri: string, secret: string }.

verifyToken(token, secret, options?)

Verifies a TOTP token against a secret.

• token (string): User-provided token with 6 to 8 digits
• secret (string): Canonical unpadded Base32 secret
• options.window (number): Time window in steps (default 1, meaning +/-30 seconds with the default period)
• options.period (number): Time step in seconds (default 30)
• options.algorithm (string): Hash algorithm (default SHA1)
• options.digits (number): Expected token length (default 6)
• options.now (number): Unix timestamp in seconds, useful for testing

Returns boolean.

generateToken(secret, counter, digits, algorithm)

Generates a TOTP token.

• secret (Buffer): Decoded secret buffer
• counter (number): Time step counter
• digits (number): Token length
• algorithm (string): Hash algorithm

Returns a zero-padded string token.

base32

RFC 4648 Base32 helpers:

• base32.encode(buffer: Buffer): string
• base32.decode(base32Str: string): Buffer

The library accepts canonical unpadded Base32 secrets. Padded or non-canonical forms are normalized or rejected before use.

Security Notes

• Token comparison uses crypto.timingSafeEqual()
• Supported algorithms are limited to SHA1, SHA256, and SHA512
• Digits are limited to 6, 7, or 8
• Period must be a positive integer
• Generated secrets use algorithm-appropriate byte lengths

Testing

npm test
npm run test:coverage
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Examples

QR Code Generation (with qrcode package)

import qrcode from 'qrcode';
import { generateURI } from '@sourceregistry/node-totp';

const { uri } = generateURI({
  issuer: 'MyApp',
  account: 'user@example.com'
});

const qrDataUrl = await qrcode.toDataURL(uri);
// Display qrDataUrl in your HTML template
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Express.js Integration

import express from 'express';
import { generateURI, verifyToken } from '@sourceregistry/node-totp';

const app = express();

// Setup route
app.get('/2fa/setup', (req, res) => {
  const { uri, secret } = generateURI({
    issuer: 'MyApp',
    account: req.user.email
  });
  
  // Store secret securely (encrypted) in user database
  req.user.totpSecret = secret;
  
  res.json({ uri });
});

// Verify route
app.post('/2fa/verify', (req, res) => {
  const { token } = req.body;
  const isValid = verifyToken(token, req.user.totpSecret, {
    window: 1
  });
  
  res.json({ valid: isValid });
});
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License

Apache-2.0 © A.P.A. Slaa

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Note: This library is designed for server-side Node.js applications. For browser usage, consider using a Web Crypto API compatible alternative.