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SecurityTrails Blog · Dec 17 2019 · by Sara Jelen

Two-Factor Authentication vs. Multi-Factor Authentication: Differences Explained

Reading time: 7 minutes

The number of people who rely on weak passwords such as “Password1234” has long been worrisome, so it’s no surprise that stolen credentials are one of the most common causes of data breaches. Even a more complex password can’t guarantee safety from cyber attacks.

This is why additional layers of security are needed, to make it more difficult for crackers to access your online accounts and sensitive data. Fortunately, two-factor authentication (2FA) and multi-factor authentication (MFA) provide those added security layers, in the form of requirements the user must fulfill in order to be granted access. And not using 2FA or MFA can lead to your wondering why your website was hacked.

These two terms are often used interchangeably, and the differences between them might not be so clear. So today, we’ll explore 2FA and MFA, examining their differences and the advantages of one over the other.

The 4 authentication factors

Before we jump into two-factor and multi-factor authentication and their differences, we should get familiar with what an authentication factor is. Both two- and multi-factor authentication refer to the authentication technologies and methods used to verify user identity and control access to sensitive data. Hence, these methods are considered authentication factors.

They are generally categorized as four authentication factors, but you may also come across different versions of a fifth factor, such as something you do, or even time itself. The four most frequently used authentication factors are:

  1. Knowledge

The most commonly used authentication factor, this is one we see on nearly every website or online service. Knowledge refers to something only the user should know in order to access the account. This can be a password, username, answer to a security question, PIN or an address.

  1. Possession

This type of authentication factor refers to something a user has in his possession, a device or an object that will provide additional information needed for verification. We mostly see this factor in action with one-time passwords sent as an SMS to your mobile device, security token, software token, card verification value on a credit card (CVV), etc.

  1. Inherence

Something you “are” is the inherence authentication factor. This refers to characteristics that are unique to the user and can be used for identification. Inherence factor examples include fingerprint, facial recognition, iris and retina print, voice recognition and other biometrics.

  1. Location

While the location authentication factor may not be used as frequently as the others, it nevertheless constitutes a factor. By definition, it refers to where you are. Your location is tracked and determined using different technologies that track your IP address, and they notify you if they see, for example, activity from Switzerland if you’ve set your location in the US. Determining your location can also be done using MAC address or devices with a GPS tracker.

2FA vs. MFA

Knowledge is the most commonly used authentication factor. However, presenting single-factor authentication offers the lowest level of security, as all that the hackers need to gain access to your account is a password. Fortunately, many organizations, websites and online services are outgrowing single-factor authentication, or SFA, and are adding an additional layer of security by combining the knowledge and possession authentication factors.

Two-factor authentication

As two-factor authentication is also considered multi-factor authentication, it can be difficult to differentiate between the two. Let’s take a look at how the number of authentication factors they utilize determines why every 2FA is an MFA, but not every MFA is a 2FA.

To better understand 2FA, let’s examine a common scenario utilizing two-factor authentication: When signing into your Google, Facebook or Amazon account, and after you’ve entered your password as the ‘something you know’ factor, you get an alert asking you to approve access, or you get an SMS code, considered the ‘something you have’ factor. That second factor can also be based on your biometrics or location, but what always stays the same is that there are two of them.

Multi-factor authentication

Multi-factor authentication considers the use of two or more authentication factors. Utilizing a password and approving access to the application alert is better than using only the knowledge factor for verification; and adding yet another authentication factor, such as a fingerprint, creates even more barriers for attackers trying to gain access to your online accounts. You’ll often find mentions of 3FA, 4FA, etc, but these are all sub-categories of MFA.

This is why we can say that every 2FA is an MFA, but not every MFA has only two authentication factors.

What is the difference between 2FA and MFA?

If we’re talking about the differences between two-factor authentication and multi-factor authentication, then we need to think of MFA strictly as using at least three authentication factors. And besides the obvious difference in the number of authentication factors they use, each comes with a different level of security and ease of implementation, as well as a varying amount of time needed for the verification process.

Security

Even though it can be fairly easy for an attacker to perform a brute force attack for less complex passwords, having to deal with SMS message authentication makes it that much more complicated and tiresome for the attacker to gain access to your account. Still, as we’ve seen already, phone authentication and phone numbers as identifiers are not that secure.

This is why adding a third authentication factor, such as biometrics (which are much more difficult to hack), will add an additional level of protection to your sensitive information. Following this line of reasoning, we would deduce that MFA is superior to 2FA, but there’s one more aspect we must consider when talking about their differences.

Ease of use

With a greater number of authentication factors needed to verify user identity comes a more time-consuming and reliable process. Users can find this unfavorable, encouraging them to “cut corners” with weak, easy-to-remember passwords which are the same on multiple accounts. This alone will undermine the effectiveness of having three authentication factors, so 2FA becomes a more reasonable option.

Also, with only two authentication factors to consider, users don’t need to go through sometimes unreliable and inconvenient biometrics verification. In the case of facial recognition, a lack of proper lighting can result in users getting locked out, unable to accurately confirm their identity. And fingerprint scanners can be tricky—sometimes a device will only recognize someone’s print if they put their finger in one specific position.

Unlike biometrics, the location factor is something that won’t, when implemented, require any action from the user. This factor makes MFA a much more user-friendly option, putting it at the same ease-of-use level as 2FA.

By minding the type of authentication factors used, we can find that right balance of security and convenience needed to make the authentication process secure enough without interfering with the user experience.

Conclusion

Multi-factor authentication is clearly the more secure authentication method, as it considers two or more authentication factors, making it harder for attackers to bypass the additional layers of security. But while MFA is the more secure option, 2FA is easier to use for a larger number of users, as well as more cost-effective to implement for both users and organizations.

In the end, choosing an authentication method is really up to you. With that in mind, we strongly emphasize the importance of using any type of MFA on your email, your domain contact email to avoid domain theft, your domain name registrar, and all your online accounts.


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SARA JELEN

Sara is a cybersecurity writer who’s passionate about the cultural impact of cybersecurity and hacker culture. She is covering not only technical topics, but also focusing on the human aspect of the field, going beyond the technological side and interested in the cognitive and social factors that influence cybersecurity practices and the industry as a whole.