Authentication is often simplified as types, or factors, of authentication. Entities can authenticate with any one of these factors, and administrators often combine two factors for dual-factor authentication, and two or more factors for multifactor authentication. If you’re planning to take the Security+ exam, you should have a basic understanding of selecting appropriate authentication factors.
For example, can you answer this question?
Q. Your network infrastructure requires users to authenticate with something they are and something they know. Which of the following choices BEST describes this authentication method?
A. Passwords
B. Dual-factor
C. Biometrics
D. Diameter
More, do you know why the correct answer is correct and the incorrect answers are incorrect. The answer and explanation is available at the end of this post.
Dual-Factor and Multifactor Authentication
Dual-factor authentication (sometimes called two-factor authentication) uses two different factors of authentication such as something you have and something you know. Dual-factor authentication often uses a smart card and a PIN, a USB token and a PIN, or combining a smart card or hardware token with a password. In each of these cases, the user must have something and know something.
Multifactor authentication uses two or more factors of authentication. For example, you can combine the something you are factor with one or more other factors of authentication.
Note that technically you can call an authentication system using two different factors either dual-factor authentication or multifactor authentication. Multifactor authentication indicates multiple factors and multiple is simply more than one.
It’s worth noting that using two methods of authentication in the same factor is not dual-factor authentication. For example, requiring users to enter a password and a PIN (both in the something you know factor) is single-factor authentication, not dual-factor authentication. Similarly, using a thumbprint and a retina scan is not dual-factor authentication.
Remember this
Two or more methods in the same factor of authentication (such as a PIN and a password) is single-factor authentication. Dual-factor (or two-factor) authentication uses two different factors such as a USB token and a PIN. Multifactor authentication uses two or more factors.
Something You Have Factor
The something you have authentication factor refers to something you can physically hold. This smart cards, CAC, and PIV.
Smart Cards
Smart cards are credit card-sized cards that have an embedded microchip and a certificate. Users insert the smart card into a smart card reader, similar to how someone would insert a credit card into a credit card reader. The smart card reader reads the information on the card, including the details from the certificate.
The embedded certificate allows the use of a complex encryption key and provides much more secure authentication than is possible with a simple password. Additionally, the certificate can be used with digital signatures and data encryption. The smart card provides confidentiality, integrity, authentication, and non-repudiation.
Requirements for a smart card are:
- Embedded certificate. The embedded certificate holds a user’s private key (which is only accessible to the user) and is matched with a public key (that is publicly available to others). The private key is used each time the user logs on to a network.
- Public Key Infrastructure (PKI). Chapter 10 covers PKI in more depth, but in short, the PKI supports issuing and managing certificates.
Smart cards are often used with another factor of authentication. For example, a user may also enter a PIN or password, in addition to using the smart card. Because the smart card is in the something you have factor and the PIN is in the something you know factor, this combination is dual-factor authentication.
CACs and PIVs
A Common Access Card (CAC) is a specialized type of smart card used by the U.S. Department of Defense. In addition to including the capabilities of a smart card, it also includes a picture of a user and other readable information. Users can use the CAC as a form of photo identification to gain access into a secure location. For example, they can show their CAC to guards who are protecting access to secure areas. Once inside the secure area, users can use the CAC as a smart card to log on to computers.
Similarly, a Personal Identity Verification (PIV) card is a specialized type of smart card used by U.S. federal agencies. It also includes photo identification and provides confidentiality, integrity, authentication, and non-repudiation for the users, just as a CAC does.
CACs and PIVs both support dual-factor authentication (sometimes called two-factor authentication) because users generally log on with the smart card and by entering information they know such as a password. Additionally, these cards include embedded certificates used for digital signatures and encryption.
Remember this
Smart cards are often used with dual-factor authentication where users have something (the smart card) and know something (such as a password or PIN). Smart cards include embedded certificates used with digital signatures and encryption. CACs and PIVs are specialized smart cards that include photo identification. They are used to gain access into secure locations and to log on to computer systems.
Q. Your network infrastructure requires users to authenticate with something they are and something they know. Which of the following choices BEST describes this authentication method?
A. Passwords
B. Dual-factor
C. Biometrics
D. Diameter
Answer is B. This is dual-factor authentaication because users must authenticate with two different factors of authentication (something you are and something you know).
Passwords are in the something you know factor and biometrics are in the something you are factor, but the scenario includes both factors, not just one.
Diameter is a remote access authentication service that supports Extensible Authentication Protocol (EAP).