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ARUL SELVI ML
ARUL SELVI ML

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MFA

Multi Factor Authentication, commonly called MFA, is a security method that requires users to verify their identity using more than one factor. Usually, this includes something you know such as a password and something you have such as a token or mobile device.

This blog explains how MFA tokens work in both offline and online situations in a simple way.

What is an MFA Token

An MFA token is a code that is generated to verify a user during login. This code is usually temporary and changes frequently. It can be generated using an app, a hardware device, or received through messages.

Types of MFA Tokens

There are two common types of MFA tokens:

  • Time based tokens
  • Server verified tokens

These two types explain how MFA works in offline and online modes.

How MFA Works in Offline Mode

In offline mode, the token is generated without needing internet access.

How it works

  1. When you first set up MFA, a secret key is shared between the server and your device.
  2. This key is stored securely on your device.
  3. The MFA app uses the current time and the secret key to generate a code.
  4. This code changes every 30 seconds.
  5. You enter this code during login.
  6. The server also generates the same code using the same key and time.
  7. If both codes match, access is granted.

Key idea

The device and server independently generate the same code without communication.

Example

Apps like Google Authenticator or Microsoft Authenticator generate codes even without internet.

How MFA Works in Online Mode

In online mode, the token is generated or verified using a server.

How it works

  1. You enter your username and password.
  2. The server generates a one time password.
  3. The code is sent to your phone through SMS, email, or push notification.
  4. You enter the received code.
  5. The server verifies the code.
  6. If correct, access is granted.

Example

You receive a login code via SMS when signing into an account.

Difference Between Offline and Online MFA

Offline MFA

  • No internet required on user device
  • Code generated locally
  • Faster and more secure against network attacks

Online MFA

  • Requires internet or network
  • Code is sent from server
  • Easier for beginners to use

Why MFA is Important

MFA adds an extra layer of security. Even if someone knows your password, they cannot access your account without the token.

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