Authentication

Authentication validates the claim of identity using one or more authentication factors. In the information security world, these factors are classified as follows:

• Something you know: A secret such as a token, a password, or a passphrase
• Something you are: Biometric features such as fingerprints, facial geometry, or eye pattern
  
• Something you have: Physical possession of a device such as a smartphone, an email account, or an authentication token key fob
  

In a client-server environment, based on the use case, authentication of a client application or device can be performed by the server itself or by a separate authentication server. In the context of IIoT, we shall review some of these authentication mechanisms later in this chapter.

False acceptance rate (FAR) and false rejection rate (FRR) are two commonly performance measures for any authentication technology. False acceptance occurs when the system misidentifies an entity as an authorized user and grants access when it should have been denied. This causes a breach in confidentiality and integrity. In the case of false rejection, an authorized user is denied access, which impacts availability of systems and resources. Both these error rates need to be factored in when designing access management systems.