EinmalpasswortToken

EinmalpasswortToken, often shortened to OTP token, is a hardware or software device used to generate a one-time password (OTP). These tokens are a crucial component in two-factor authentication (2FA) or multi-factor authentication (MFA) systems, enhancing security by requiring a second, time-sensitive credential in addition to a traditional password.

There are primarily two types of OTP tokens: hardware tokens and software tokens. Hardware tokens are physical devices, often resembling key fobs or small calculators. They typically display a rotating sequence of numbers that changes at regular intervals, usually every 30 to 60 seconds. This dynamic code is then entered by the user along with their primary password. Software tokens, on the other hand, are applications installed on a user's smartphone or computer. These applications generate OTPs in a similar fashion to hardware tokens, providing a convenient and often free alternative.

The core principle behind OTP tokens is their time-based or event-based generation of unique passwords. Time-based OTP (TOTP) tokens synchronize with a server and generate codes based on the current time. Event-based OTP (HOTP) tokens generate codes based on a counter that increments with each use. The short lifespan of these passwords significantly reduces the risk of replay attacks, where an attacker might intercept a password and use it later. Once an OTP is used or expires, it becomes invalid, rendering any intercepted credentials useless for future access. This makes OTP tokens a widely adopted security measure for sensitive online accounts and systems.