Editing Authentication protocol (section)

==Purpose ==

With the increasing amount of trustworthy information being accessible over the network, the need for keeping unauthorized persons from access to this data emerged. Stealing someone's identity is easy in the computing world - special verification methods had to be invented to find out whether the person/computer requesting data is really who he says he is.<ref>{{cite web|url = http://www.techrepublic.com/article/understanding-and-selecting-authentication-methods/|title = Understanding and selecting authentication methods|date = 28 August 2001|access-date = 30 October 2015|website = www.techrepublic.com|last = Shinder|first = Deb}}</ref> The task of the authentication protocol is to specify the exact series of steps needed for execution of the authentication. It has to comply with the main protocol principles:
# A Protocol has to involve two or more parties and everyone involved in the protocol must know the protocol in advance.
# All the included parties have to follow the protocol.
# A protocol has to be unambiguous - each step must be defined precisely.
# A protocol must be complete - must include a specified action for every possible situation.
An illustration of password-based authentication using simple authentication protocol:

Alice (an entity wishing to be verified) and Bob (an entity verifying Alice's identity) are both aware of the protocol they agreed on using. Bob has Alice's password stored in a database for comparison. 
# Alice sends Bob her password in a packet complying with the protocol rules.
# Bob checks the received password against the one stored in his database. Then he sends a packet saying "Authentication successful" or "Authentication failed" based on the result.<ref>{{Cite book|title = Fundamentals of Cryptology|last = van Tilborg|first = Henk C.A.|publisher = Kluwer Academic Publishers|year = 2000|isbn = 0-7923-8675-2|location = Massachusetts|pages = 66–67}}</ref>
This is an example of a very basic authentication protocol vulnerable to many threats such as [[eavesdropping]], [[replay attack]], [[man-in-the-middle]] attacks, [[Dictionary attack|dictionary attacks]] or [[Brute-force attack|brute-force attacks]]. Most authentication protocols are more complicated in order to be resilient against these attacks.<ref>{{Cite book|title = Internet Cryptography|last = Smith|first = Richard E.|publisher = Addison Wesley Longman|year = 1997|isbn = 0-201-92480-3|location = Massachusetts|pages = [https://archive.org/details/internetcryptogr0000smit/page/1 1–27]|url = https://archive.org/details/internetcryptogr0000smit/page/1}}</ref>