Biometric Authentication: Verifying a User's Identity Using a Frequentist Probability Model of Keystroke Intervals

Biometric Authentication: Verifying a User's Identity Using a Frequentist Probability Model of Keystroke Intervals

Misha Voloshin (Mighty Data, Inc., USA)
DOI: 10.4018/978-1-4666-5063-3.ch011


User authentication is the keystone of information security. Even the most craftily built and diligently monitored computer system will crumble if there is a flaw in its user authentication system(Minaev, 2010). A hacker able to exploit such a flaw will be able to convince the computer system that he is a legitimate user – possibly even a specific legitimate user, entitled to all of the abilities to read or modify that user's data, or implicate that user in misdeeds that could lead to personal or professional harm. A hacker could even impersonate the system administrator herself, giving the hacker the ability to not only access all of that system's data but also to subvert the very same network monitors and automated alerting systems that would notify the real administrator of the hacker's activity(occupytheweb, 2013). This chapter introduces a mechanism that an administrator can use for increasing the strength of a computer's user authentication system and triggering a lockout and/or emailing an alert if an impostor is suspected to be accessing a user's account. It works by measuring the time intervals between keystrokes as a user types, relying on the fact that most individuals have distinct and identifiable typing patterns that can be discerned through statistical analysis.
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1. Introduction And Background

In the industry, user authentication is categorized into three types of authentication factors describing the fundamental means by which the user proves his own identity (Harris, 2012).

By far the most commonly used of these (in information technology, at least) is called a knowledge factor, and it refers to some piece of information that the legitimate user knows, such as a password, a social security number, or a mother’s maiden name. Any console, website, smartphone, or bank system that can be accessed merely by inputting a series of keyboard characters is dependent on knowledge-factor authentication (Ballad, 2010).

Another less-used but widely-accepted authentication factor is a possession factor, and it refers to some physical object that the legitimate user has. Examples include a tamper-resistant USB dongle that the user has to plug into the computer in order to log in, or a keyfob with an RFID tag inside it (SafeNet, 2012).

Many systems in the banking(Federal Financial Institutions Examination Council, 2005) and military(Bush, 2004) sectors, in order to comply with regulatory mandates, combine both knowledge-factor authentication and possession-factor authentication, thus obeying a principle called two-factor authentication. For example, the fact that an ATM console requires a user to both swipe a debit card (possession factor) and enter a PIN code (knowledge factor) means that the ATM is compliant with two-factor authentication requirements.

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