In fact, biometric technology has been known since ancient Egyptian times. The recordings of countenance and size of recognizable body parts are normally used to ensure that the person is the truly him/ her.
It was the beginning of the system security work-flow. Logically, no one has access without being trusted. Access control technology tries to automate the process of answering two basic questions before offering various types of access.
The first question is “Who are you?” and the second question is “Are you really as you say?” The first question represents the function of identification and the second question represents the function of verification (proof).
The common approach to gain the access is through the use of signs and assumptions that the owner of the sign and the proof identity will match. This kind of model is called as single-factor security. For example is the key of house or password.
This kind of approach has a risk if the sign is lost or stolen. Once the key falls into the hands of others, they could freely enter the house. It also happens with a password. It will not be a secret anymore and someone else can use it.
To overcome this problem, two-factor security is made. This method is more resilient to risks. The most common example is the card of automated teller machine (ATM). With a card that shows who you are and PIN which is the mark you as the rightful owner of the card, you can access your bank account. The weakness of this security is that both signs should be at the requester of access. Thus, the card only or PIN only will not work.
Problems arise when you are forgetful person. Also, you often do not realize that the PIN is very personal thing. Basically, family or close friends may not know. The more sophisticated crime is to steal the PIN data from the source directly.