What is OTP and how does it work?

OTP (One-Time Password) is a single-use password used for authentication and is valid only for one session or transaction.

How OTP works:

• A unique password is generated that cannot be reused.
• It can be based on time (TOTP — Time-based One-Time Password) or a counter (HOTP — HMAC-based One-Time Password).
• The user receives the OTP via SMS, an authenticator app (e.g., Google Authenticator), or email.
• When entering the OTP, the system verifies its correctness and validity.

Example of TOTP:

1. The server and client share a secret key.
2. Based on the current time and the key, a password is generated using a hash function.
3. The password is valid, for example, for 30 seconds.
4. The user enters the password, and the server checks for a match.

OTP enhances security because even if the password is intercepted, it cannot be reused.