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Multi-factor authentication (MFA) is an
Two-factor authentication (also known as 2FA) is a type, or subset, of multi-factor authentication. It is a method of confirming users' claimed identities by using a combination of two different factors: 1) something they know, 2) something they have, or 3) something they are.
A good example of two-factor authentication is the withdrawing of money from an
Two other examples are to supplement a user-controlled password with a
Two-step verification or two-step authentication is a method of confirming a user's claimed identity by utilizing something they know (password) and a second factor other than something they have or something they are. An example of a second step is the user repeating back something that was sent to them through an
The use of multiple authentication factors to prove one's identity is based on the premise that an unauthorized actor is unlikely to be able to supply the factors required for access. If, in an authentication attempt, at least one of the components is missing or supplied incorrectly, the user's identity is not established with sufficient certainty and access to the asset (e.g., a building, or data) being protected by multi-factor authentication then remains blocked. The authentication factors of a multi-factor authentication scheme may include:[
Knowledge factors are the most commonly used form of authentication. In this form, the user is required to prove knowledge of a secret in order to authenticate.
Possession factors ("something the user and only the user has") have been used for authentication for centuries, in the form of a key to a lock. The basic principle is that the key embodies a secret which is shared between the lock and the key, and the same principle underlies possession factor authentication in computer systems. A
Disconnected tokens have no connections to the client computer. They typically use a built-in screen to display the generated authentication data, which is manually typed in by the user.[
Connected tokens are
These are factors associated with the user, and are usually
Increasingly, a fourth factor is coming into play involving the physical location of the user. While hard wired to the corporate network, a user could be allowed to login utilizing only a pin code while off the network entering a code from a soft token as well could be required. This could be seen as an acceptable standard where access into the office is controlled.
Systems for network admission control work in similar ways where your level of network access can be contingent on the specific network your device is connected to, such as wifi vs wired connectivity. This also allows a user to move between offices and dynamically receive the same level of network access in each.