Authentication protocol: Difference between revisions

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{{Short description|Type of cryptographic protocol}}

An '''authentication protocol''' is a type of computer [[communications protocol]] or [[cryptographic protocol]] specifically designed for transfer of [[authentication]] data between two entities. It allows the receiving entity to authenticate the connecting entity (e.g. Client connecting to a Server) as well as authenticate itself to the connecting entity (Server to a client) by declaring the type of information needed for authentication as well as syntax.<ref>{{cite web|url = https://www.sans.org/reading-room/whitepapers/authentication/overview-authentication-methods-protocols-118|title = An Overview of Different Authentication Methods and Protocols|date = 23 October 2001|access-date = 31 October 2015|website = www.sans.org|publisher = SANS Institute|last = Duncan|first = Richard}}</ref> It is the most important layer of protection needed for secure communication within computer networks.

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# 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>

==Types==

===Authentication protocols developed for PPP [[Point-to-Point Protocol]]===

Protocols are used mainly by [[Point-to-Point Protocol]] (PPP) servers to validate the identity of remote clients before granting them access to server data. Most of them use a password as the cornerstone of the authentication. In most cases, the password has to be shared between the communicating entities in advance.<ref>{{cite documentCiteSeerX|title = Public-key cryptography and password protocols|last = Halevi|first = Shai| year=1998 | pages=230–268 |citeseerx = 10.1.1.45.6423}}</ref>

[[File:PAP 2way handshake.png|thumb|PAP 2-way handshake scheme|461x461px]]

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====CHAP - [[Challenge-handshake authentication protocol]]====

The authentication process in this protocol is always initializedinitiated by the server/host and can be performed anytime during the session, even repeatedly. ServerThe server sends a random string (usually 128B long). The client uses the password and the string received as parametersinput forto MD5a hash function and then sends the result together with username in plain text. ServerThe server uses the username to apply the same function and compares the calculated and received hash. An authentication is successful orwhen the calculated and received hashes unsuccessfulmatch.

====[[Extensible Authentication Protocol|EAP - Extensible Authentication Protocol]]====

EAP was originally developed for PPP(Point-to-Point Protocol) but today is widely used in [[IEEE 802.3]], [[IEEE 802.11]](WiFi) or [[IEEE 802.16]] as a part of [[IEEE 802.1x]] authentication framework. The latest version is standardized in RFC 5247. The advantage of EAP is that it is only a general authentication framework for client-server authentication - the specific way of authentication is defined in its many versions called EAP-methods. More than 40 EAP-methods exist, the most common are:

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[[Remote Authentication Dial-In User Service]] (RADIUS) is a full [[AAA (computer security)|AAA protocol

]] commonly used by [[ISP]]s. Credentials are mostly username-password combination based, and it uses [[Network access server|NAS]] and [[User Datagram Protocol|UDP]] protocol for transport.<ref>{{cite web|url = http://www.cisco.com/c/en/us/td/docs/net_mgmt/cisco_secure_access_control_system/5-1/user/guide/acsuserguide/rad_tac_phase.html|title = AAA protocols|access-date = 31 October 2015|website = www.cisco.com|publisher = CISCO}}</ref>

====[[DIAMETER]]====

[[Diameter (protocol)]] evolved from RADIUS and involves many improvements such as usage of more reliable TCP or [[SCTP]] transport protocol and higher security thanks to [[Transport Layer Security|TLS]].<ref>{{cite web|url = http://www.ibm.com/developerworks/wireless/library/wi-diameter/|title = Introduction to Diameter|date = 24 January 2006|access-date = 31 October 2015|website = www.ibm.com|publisher = IBM|last = Liu|first = Jeffrey}}</ref>

===Other===

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==List of various other authentication protocols==

* [[AKA (security)|AKA]]

* [[Basic access authentication]]

* [[CAVE-based authentication]]

* [[CRAM-MD5]]