Time-based One-Time Password (TOTP) Authentication

TOTP is a popular method of implementing Two-Factor Authentication (2FA) that generates a one-time password based on the current time.

Steps:

1. Secret Key Generation: A unique secret key is generated for each user during the setup process. This secret key is known only to the user and the authentication system.

2. Initial Configuration: The user configures their authentication device, such as a smartphone or authentication app, with the secret key.

3. Time-Based Generation: When the user attempts to log in, the authentication system generates a one-time password based on the current time and the shared secret key. The current time is typically divided into time intervals, often 30 seconds.

4. Algorithm Calculation: The one-time password is calculated using a cryptographic algorithm, usually HMAC-SHA1, which combines the current time interval with the secret key. This calculation ensures that the generated password is unpredictable and unique for each time interval.

5. User Input: The authentication system prompts the user to enter the one-time password generated by their authentication device.

6. Validation: The authentication system independently calculates the one-time password using the current time and the secret key associated with the user's account. If the entered password matches the calculated password, the user is successfully authenticated.

7. Expiration: After a time interval (e.g., 30 seconds), the one-time password becomes invalid, and a new password must be generated for the next time interval.

By using TOTP, the authentication process becomes more secure as the one-time passwords are valid only for a short period and are generated based on a shared secret key and the current time, making them resistant to replay attacks and interception.