A Survey of Keystroke Dynamics Biometrics <s> Data Size. <s> A long-text-input keystroke biometric system was developed for applications such as identifying perpetrators of inappropriate e-mail or fraudulent Internet activity. A Java applet collected raw keystroke data over the Internet, appropriate long-text-input features were extracted, and a pattern classifier made identification decisions. Experiments were conducted on a total of 118 subjects using two input modes - copy and free-text input - and two keyboard types - desktop and laptop keyboards. Results indicate that the keystroke biometric can accurately identify an individual who sends inappropriate email (free text) if sufficient enrollment samples are available and if the same type of keyboard is used to produce the enrollment and questioned samples. For laptop keyboards we obtained 99.5% accuracy on 36 users, which decreased to 97.9% on a larger population of 47 users. For desktop keyboards we obtained 98.3% accuracy on 36 users, which decreased to 93.3% on a larger population of 93 users. Accuracy decreases significantly when subjects used different keyboard types or different input modes for enrollment and testing. <s> BIB001 </s> A Survey of Keystroke Dynamics Biometrics <s> Data Size. <s> User authentication is an important problem for any restricted access computer system, especially with remote access. Constant spread of Internet makes efficient remote authentication a pressing issue while the distributed nature of interaction introduces additional difficulties. Authentication methods based on most biometrics techniques require dedicated hardware that is unhandy for remote applications. In contrast keystroke dynamics requires only limited dedicated software and does not require any dedicated hardware. The approach we propose is aimed at efficient user authentication with keystroke dynamics using short fixed text, that may for example occur simultaneously to logging process. We have tested the suggested approach on a large group of individuals, with data gathered over Internet using browser-based WWW application. The obtained results are promising and encourage further development in this area. <s> BIB002
It is collectively agreed that experiments that includes large number of subjects better signify the scalability of study. Regrettably most of the studies performed involve only small number of subjects. This is understandable due to various issues and difficulties encountered in data collection process (to be discussed in the following section). Generally most research works involve less than 50 subjects, with a vast amount as low as 10 to 20 people. Although some research works reported to have involved large number of users (118 BIB001 and 250 BIB002 users), only a portion of the population completed the entire experimental cycle. A clear overview on the frequency distribution of data population has been summarized in Figure 3. 