OneTimePasswords

One-time passwords, often abbreviated as OTPs, are a crucial component of modern security systems. These are authentication codes that are valid for only a single use or session. Unlike static passwords that remain the same until changed, OTPs are dynamic and generated for immediate use. This temporary nature significantly enhances security by mitigating the risk of replay attacks, where an attacker intercepts and reuses a stolen password.

OTPs are commonly used in two-factor authentication (2FA) or multi-factor authentication (MFA) processes. When a user attempts to log in, after entering their primary password, they are prompted for an OTP. This second factor of authentication confirms the user's identity, providing an additional layer of protection.

There are several methods for generating and delivering OTPs. Time-based One-Time Passwords (TOTP) are widely used and are synchronized between the server and the user's device, typically a smartphone app like Google Authenticator or Authy. Event-based One-Time Passwords (HOTP) are generated based on a counter, incrementing with each new OTP. OTPs can also be delivered via SMS messages or generated by hardware tokens. The reliance on a separate, dynamic credential makes OTPs a robust defense against common credential theft techniques.