What is a One-Time Password (OTP)?
A one-time password (OTP) is a password that is valid for a single use to access a computer system.
Traditional fixed passwords are vulnerable to unauthorized access if they are leaked to third parties. Password breaches can occur due to eavesdropping on communication channels, brute-force attacks over a long period, and other methods, often without the legitimate user's awareness. In contrast, a one-time password is valid only for one use, making it highly effective in preventing unauthorized access due to password leaks. OTPs are widely used in scenarios requiring high security, such as online banking, web-based email applications, and online gaming.
In earlier implementations, OTPs were typically generated using dedicated hardware tokens. These tokens synchronize their clocks with the system being accessed and generate a new number (OTP) periodically. Users activate the token during login, retrieve the displayed OTP, and use it as their login password. This method is known as time-synchronized OTP.
More recently, the challenge-response OTP method has gained popularity, with smartphones being a common tool for this approach. In this process, users pre-register their smartphone with the target system. During login, they first enter their user ID and password. The system then sends the OTP to the user's smartphone, typically via SMS, email, or a dedicated app. The user inputs the received OTP on the login screen to complete the process. Since these systems use two layers of authentication, they are often referred to as two-step verification or two-factor authentication (2FA).
F5 BIG-IP Access Policy Manager (APM) facilitates the efficient implementation of challenge-response OTP systems, enhancing security without sacrificing usability.