Two-Factor Authentication (TOTP)

What is it?

This technology is often referred to as 2FA (Two-Factor Authentication) or MFA (Multi-Factor Authentication).

It is based on open standards from the Initiative for Open Authentication (OATH). It is not related to OAuth, which is a different protocol used for authorizing apps (e.g., "Log in with Google").

The standards are outlined in RFC 4226 (Hash-based OTP, or HOTP) and RFC 6238 (Time-based OTP, or TOTP).

You can use Google Authenticator on your Android or iOS phone to provide second-factor authentication for Google accounts, Linux boxes, LastPass, Bitwarden, and other services.

Links

• Google Authenticator

  • Google Play Store listing
  • Apple App Store listing
  • Source code on GitHub

• Google accounts

  • Blog post detailing the introduction of second factor for Google accounts

• Bitwarden

  • Official Website
  • Vaultwarden (Self-hosted alternative) Wiki

• LastPass

  • Download link
  • Help page on Google Authenticator

• PAM for UNIX

  • Example of how to set up OTP with Linux

• Amazon Web Services (AWS) accounts

  • AWS multi-factor account start page