Authentication is the technique by which a system check the identification of a end User who wants to access it. Since entrance or access control is normally based on the identification of the User who demand access to a resource, Authentication is essential to effective Security.

Below are four main types of Technologies for authentication:-

1. Password based authentication technologies
2. Certificate based authentication technologies
3. E-Token based authentication technologies
4. Biometric based authentication technologies

1.) Password Based Technologies:-

Passwords are the most common form of authentication. Password may be of any form(String of alphabets, numbers and special characters). This password is necessarily to be known by the ENTITY or the THING or a PERSON that is being Authenticated.

This authentication Process takes places(password) by:

• Prompts for user id and password.
• User enters user id and password.
• User id and password validation.
• Authentication result back to the server.
• Inform user accordingly.

2.) Certificate Based Technologies:-

It is a digital document which digitally signed by a reliable third party known as the Certificate Authority (CA). Then these Digital Certificates can be reused for user authentication. Certificate based authentication is stable as compared to password based authentication. Because here end user is suppose to HAVE something(CERTIFICATE) rather than to KNOW something(PASSWORD). Electronic document contains information of The Entity it belongs to.., The Entity it was issued by.., Unique serial number or some other unique identification.., Valid date.. A Digital fingerprint..

This authentication Process takes places(certificate) by:

• Creation, storage and distribution of DC(Digital Certificate).
• Login request (user to server).
• Server creates a random challenge.
• User signs the random challenge.
• Server returns an appropriate message back to the user.

3.) E-Token Based Technologies:-

An E-Token authentication is a small device that develop/generates a new odd/random value every time it is used. This random value becomes the basis for authentication(an alternative to a password). It can be implemented on a USB key fob or on a smart card. Data is protected on the device itself. May store credentials such as passwords, digital signatures and certificates, and private keys. E-Token has different components or features like Processor, LCD for displaying outputs or random values, Battery, Small keypad for entering information, Real-time clock.

This Authentication Process takes places(e-token) by:

• Creation of a token.
• Use of token.
• Token validation.
• Server returns an appropriate message back to the user.

4.) Biometric Based Technologies:-

Biometric authentication mention to the realization/recognition/identification of humans by their personality/characteristics such as Face, fingerprint, human voice, Retina, Iris pattern of the eye, vein pattern etc. It's used in computer science as a form of realization/recognition and access control. It is also used to find/select persons in groups that are under consideration/measurement.

This Authentication Process takes places(Biometric) by:

• Database consist of a sample of users biometric characteristics.
• During Authentication process, User is compulsory/mandatory to give a new pattern/sample of the users biometric.
• This pattern is sent to encryption.
• This patters/sample is decrypted & related/compared.(if pattern matches)
• User is treated as valid one.