Two-factor authentication (2fa)

TL;DR: A method of authenticating a user that requires two steps, usually a combination of something the user knows (password) and something the user has (e.g. a mobile phone).

Two-Factor Authentication (2FA) is a security method that uses two different types of authentication factors to verify a user's identity. This significantly increases security compared to simply entering a password. The authentication factors are divided into three main categories:

1. Knowledge: Something the user knows (e.g. password or PIN).
2. Possession: Something that the user owns (e.g. a mobile phone, a hardware token).
3. Biometrics: Something that is the user (e.g. fingerprint, facial recognition).

How 2FA works:

When using 2FA, a user must provide two of these factors to gain access to a system or application. Here is a typical process:

1. First factor (knowledge): The user enters their password or PIN to start the login process.
2. Second factor (possession or biometrics): The user must then provide a second factor. This can be a one-off code sent to their mobile phone, a fingerprint scan or another authentication mechanism.

Examples of 2FA:

• SMS-based authentication: After entering the password, the user receives a one-time code via SMS, which they must enter in order to log in.
• App-based authentication: The user uses an authentication app (such as Google Authenticator or Authy) that generates time-based one-time passwords (TOTP). After entering the password, the user enters the code displayed in the app.
• Hardware token: The user has a physical device (e.g. a YubiKey) that generates a one-time code or is connected via USB to provide the second factor.
• Biometric authentication: The user uses their fingerprint or facial recognition as a second factor after entering the password.

Advantages of 2FA:

1. Increased security: The combination of two different authentication factors significantly improves security. Even if one factor (e.g. the password) is compromised, the second factor is still required.
2. Protection against phishing and brute force attacks: Attackers need access to both authentication factors, which makes it much more difficult for them to gain unauthorised access.
3. Reduction of account transfers: 2FA reduces the risk of account takeovers, as it is not enough to just know the password.

Disadvantages of 2FA:

1. User friendliness: Some users may find the additional authentication level inconvenient.
2. Dependence on second factors: If the user loses the second factor (e.g. their phone or hardware token), access to their account may be temporarily restricted.
3. Costs and implementation: The implementation of 2FA can mean additional effort and costs for companies, especially if special hardware tokens are used.

Implementation of 2FA:

The implementation of 2FA depends on the specific application and requirements. Typical steps include:

1. Selection of 2FA methods: Decide which authentication methods (SMS, app, hardware token, biometrics) should be used.
2. Integration into systems: Integrate 2FA into existing login processes and systems. This may require the use of APIs and security protocols.
3. User training: Inform and train users about the new authentication process to ensure a smooth introduction.
4. Emergency measures: Define procedures in the event that users lose their second authentication factor or do not have access.

Conclusion:

Two-Factor Authentication (2FA) is an effective method of increasing the security of user accounts and sensitive data. By combining two independent authentication factors, the risk of unauthorised access is significantly reduced, making 2FA an important part of modern security strategies.