A Quick Overview - SFA, TFA & MFA

What is SFA - Single Factor Authentication 

This is “something a user knows.”  The most recognized type of Single Factor Authentication method is the password. Single Factor Authentication (SFA) is the traditional security process that requires a user name and password before granting access to the user.

SFA security relies on the diligence of the user, who should take additional precautions -- for example, creating a strong password and ensuring that no one can access it. For applications that require greater security, it may be advisable to implement more complex systems, such as Multi Factor Authentication.

What is TFA - Two Factor Authentication

In Two Factor Authentication, in addition to the first factor, the second factor is “something a user has.”  Examples of something a user has are a fob that generates a pre-determined code, a signed digital certificate or even a biometric such as a fingerprint.  The most recognized form of two-factor authentication is the ubiquitous RSA SecurID fob.

In a Two Factor Authentication system, the user provides dual means of identification, one of which is typically a physical token, such as a card, and the other of which is typically something memorized, such as a security code. This is a process involving two stages to verify the identity of an entity trying to access services in a computer or in a network. In a Two Factor Authentication, each step involves a different authentication factor.

An Automated Teller Machine (ATM) typically requires Two Factor Authentication. To prove that users are who they claim to be, the system requires two items: an ATM smartcard (application of the possession factor) and the personal identification number (PIN) (application of the knowledge factor). In the case of a lost ATM card, the user's accounts are still safe; anyone who finds the card cannot withdraw money as they do not know the PIN. The same is true if the attacker has only knowledge of the PIN and does not have the card. This is what makes Two Factor Authentication more secure: there are two factors required in order to authenticate.

What is MFA - Multi Factor Authentication

In Multi Factor Authentication, in addition to the previous two factors, the third factor is “something a user is.”  Examples of a third factor are all biometric such as the user’s voice, hand configuration, a fingerprint, a retina scan or similar.  The most recognized form of Multi Factor Authentication is usually the retina scan with Two Factor Authentication. 

Multi Factor Authentication is an approach to authentication which requires the presentation of the three authentication factors: a knowledge factor ("something only the user knows"), a possession factor ("something only the user has"), and an inherence factor ("something only the user is"). After presentation, each factor must be validated by the other party for authentication to occur.

Multi Factor Authentication is often confused with other forms of authentication. The Multi Factor Authentication requires the use of the three authentication factors. The factors are identified in the standards and regulations for access to U.S. Federal Government systems. These factors are:

1. Something only the user knows (e.g., password, PIN, pattern);
2. Something only the user has (e.g., ATM card, smart card, mobile phone); and
3. Something only the user is (e.g., biometric characteristic, such as a fingerprint)

The goal of MFA is to create a layered defense and make it more difficult for an unauthorized person to access a target such as a physical location, computing device, network or database. If one factor is compromised or broken, the attacker still has at least one more barrier to breach before successfully breaking into the target.

Typical MFA scenarios include:

• Swiping a card and entering a PIN.
• Downloading a VPN client with a valid digital certificate and logging into the VPN before being granted access to a network.
• Logging into a website and being requested to enter an additional one-time password (OTP) that the website's authentication server sends to the requester's phone or email address.
• Swiping a card, scanning a fingerprint and answering a security question.
• Attaching a USB hardware token to a desktop that generates an OTP and using the one-time password to log into a VPN client.

In the United States, interest in Multi Factor Authentication has been driven by regulations such as the Federal Financial Institutions Examination Council (FFIEC) directive calling for Multi Factor Authentication for Internet banking transactions.