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Security 101; Authentication December 27, 2011

Posted by Chris Mark in InfoSec & Privacy.
Tags: , , , , ,

Recently I found myself in a discussion with a person about a particular feature of payment cards.  When I started discussing the concept of authentication the look on the other persons face told me that I was discussing a completely foreign subject.

While this is not a dissertation on security authentication is a vital component of information security and fraud prevention within the payment card industry and security, in general.  For this reason, it is important to have an understanding of the concept and how it applies to our daily lives.

Authentication is described on wikipedia as:the act of establishing or confirming something (or someone) as authentic, that is, that claims made by or about the subject are true”.

There are three generally accepted factors of authentication.  1) something you know (like a password), 2) something you are (biometrics like fingerprints or iris scans), and 3) something you have (like a token).  Each of these factors alone have some value and may be sufficient to demonstrate with an appropriate degree of confidence that you are the person who is authorized to access the resource.  The degree of assurance necessary and thus the degree of required authentication is predicated upon the sensitivity of the object to which you require access.  More sensitive requires greater assurance and therefore more rigorous authentication.

Access control is defined as the combination of authorization and authentication.  Authorization is simply the approval to access a particular resource.  Consider a work environment where you are required to use a badge reader to enter the building.  As an employee you are authorized to enter the building.  To ensure that it is truly you (the authorized party) entering the building you need to provide some evidence that you are who you say you are.  In many cases, the authentication mechanism is a proximity card that is waved and the door opens.   The proximity card is a token and would be considerd as a single factor of authentication- “something you have.”.

When you get to your desk you need to access your work computer.  As an employee, you are authorized to access your email, and certain applications.  To log into the system you enter a user name (the system knows the person who owns this username is authorized to access certain resources) and then you enter your password.  This password (something you know) is a single factor of authentication that tells the system with some degree of confidence that you are the person that matches the username.

In both of these examples the astute reader has likely identified the vulnerability of single factor authentication.  In the first example a thief may have stolen the badge and may be masquarading as the legitimate user.  In the second example a person may have shared their password with another of the password may have been stolen in which case an ‘unauthorized’ person could also masquarade as a legitimate, authorized user.  When it is necessary to have an increased level of assurance that the authorized person is indeed the one accessing the resource, two factors of authentication can be used.  For the solution to truly be considered two–factor authentication it requires two of the three types of factors to be used simultaneously.  In high security areas it is common to see two factor authentication used.

Consider an example where you bank online.  Due to the sensitive nature of your account (and FFIEC regulations) the bank wants to have assurance that only the authorized account holder is accessing the account.  Since the bank website is accessed over the internet the bank is limited in their ability to confirm the identity of the user.  A password alone is not sufficient as a password can be stolen or shared.  In this scenario a bank would use a second factor of authentication.  While it does not guarantee that the person using the authentication mechanism is the authorized user it provide a much greater level of assurance than a password alone.

Payment cards possess a number of authentication mechanisms.  The objective is to authenticate the transaction or user and reduce the incidence of fraud.  In card not present transactions such as ecommerce purchases the CVV2 number is often used to authenticate the card.  Since the number is only printed on the card and it is against card brand rules (PCI DSS) to store the CVV2, the assumption is that if someone can input the CVV2 they are in possession of a valid card.  Unfortunately, it is this fact that makes CVV2 such a valuable target for data thieves.  More robust authentication mechanisms include 3DSecure (Verified by Visa, MasterCard Secure Code), EMV (Europay, MasterCard, Visa) and the PIN used in debit transactions.  While each of these technologies increase the level of assurnace that the authorized user is making a legitimate transaction it does not guarantee such.

Authorization is a critical component to any information security or fraud prevention system.  Understanding the basics fo authentication can help users better manage the security of their payment cards.


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