Depending upon whom you ask, there are either three or five factors of authentication.
Unless you ask me.
I say that there are six.
Let me explain.
First I’ll discuss what factors of authentication are, then I’ll talk about the three factor and five factor school, then I’ll briefly review my thoughts on the sixth factor—now that I know what I’ll call it.
What are factors of authentication?
Before proceeding to factors of authentication, let’s review TechTarget’s definition of authentication.
Authentication is the process of determining whether someone or something is, in fact, who or what it says it is.
From https://www.techtarget.com/searchsecurity/definition/authentication
For purposes of this post I’m going to stay away from the “something” part and concentrate on the “someone” part.

For example, if Warren Buffett has a bank account, and I claim that I am Warren Buffett and am entitled to take money from that bank account, I must complete an authentication process to determine whether I am entitled to Warren Buffett’s money. (Spoiler alert: I’m not.)
So how do I authenticate? There are many different ways to authenticate, which can be grouped into several authentication factors. Here’s how Sumo Logic defines “authentication factor.”
An authentication factor is a special category of security credential that is used to verify the identity and authorization of a user attempting to gain access, send communications, or request data from a secured network, system or application….Each authentication factor represents a category of security controls of the same type.
From https://www.sumologic.com/glossary/authentication-factor/
When considering authentication factors, the whole group/category/type definition is important. For example, while a certain system may require both a 12-character password and a 4-digit personal identification number (PIN), these are pretty much the same type of authentication. It’s just that the password is longer than the PIN. From a security perspective, you don’t gain a lot by requiring both a password and a PIN. You would gain more by choosing a type of authentication that is substantially different from passwords and PIN.
How many factors of authentication are there?
So how do we define the factors of authentication? Different people have different definitions.
Three factors of authentication

For the most part, I believe that everyone agrees on at least three factors of authentication. As I noted in a prior post on factors of authentication, NIST defines the following three factors:
Factors include: (i) something you know (e.g. password/personal identification number (PIN)); (ii) something you have (e.g., cryptographic identification device, token); or (iii) something you are (e.g., biometric).
From https://csrc.nist.gov/glossary/term/Multi_Factor_Authentication, cited in https://bredemarket.com/2022/03/19/remember-the-newer-factors-of-authentication/
Note that NIST’s three factors are very different from one another. Knowing something (such as a password or a PIN) differs from having something (such as a driver’s license) or being something (a fingerprint or a face).
But some people believe that there are more than three factors of authentication.
Five factors of authentication
Let’s add two factors to the definition trumpeted by NIST. People such as The Cybersecurity Man have included all five in their definition.
- Something you know.
- Something you have.
- Something you are.
- Something you do.
- Somewhere you are.
For more information, see my March 2021 post on the five factors of authentication.
But are there only five?
Six factors of authentication
In April 2022, I began wondering if there is a sixth authentication factor. While I struggled to put it into the “some xxx you xxx” format, I was able to encapsulate what this sixth factor was.
What about the authentication factor “why”?
This proposed factor, separate from the other factors, applies a test of intent or reasonableness to any identification request.
From https://bredemarket.com/2022/04/12/the-sixth-factor-of-multi-factor-authentication-you-heard-it-here-first/

Over the months, I struggled through some examples of the “why” factor.
- Why is a person using a credit card at a McDonald’s in Atlantic City? (Link) Or, was the credit card stolen, or was it being used legitimately?
- Why is a person boarding a bus? (Link) Or, was the bus pass stolen, or was it being used legitimately?
- Why is a person standing outside a corporate office with a laptop and monitor? (Link) Or, is there a legitimate reason for an ex-employee to gain access to the corporate office?
As I refined my thinking, I came to the conclusion that “why” is a reasonable factor of authentication, and that this was separate from the other authentication factors (such as “something you do”).
And the sixth factor of authentication is called…
You’ll recall that I wanted to cast this sixth authentication factor into the “some xxx you xxx” format.
So, as of today, here is the official Bredemarket list of the six factors of authentication:
- Something you know.
- Something you have.
- Something you are.
- Something you do.
- Somewhere you are.
(Drumroll…)
- Somewhat you why.
Yes, the name of this factor stands out from the others like a sore thumb (probably a loop).

However, the performance of this factor stands out from the others. If we can develop algorithms that accurately measure the “why” reasonableness of something as a way to authenticate identity, then our authentication capabilities will become much more powerful.













