KEYSTROKE DYNAMICS RECOGNITION USING NINE-VARIATE PREDICTION ELLIPSOID FOR NORMALIZED DATA
Sergiy B. Prykhodko, A. S. Trukhov · Radio Electronics Computer Science Control · 2025
Context. Keystroke dynamics recognition is a crucial element in enhancing security, enabling personalized user authentication, and supporting various identity verification systems. This study investigates the influence of data distribution on the performance of one-class classification models in keystroke dynamics, focusing on the application of a nine-variate prediction ellipsoid. The object of research is the keystroke dynamics recognition process. The subject of the research is a mathematical model for keystroke dynamics recognition. Unlike typical approaches assuming a multivariate normal distribution of data, real-world keystroke datasets often exhibit non-Gaussian distributions, complicating model accuracy and robustness. To address this, the dataset underwent normalization using the multivariate Box-Cox transformation, allowing the construction of a more precise decision boundary based on the prediction ellipsoid for normalized data.The objective of the work is to increase the probability of keystroke dynamics recognition by constructing a nine-variate prediction ellipsoid for normalized data using the Box-Cox transformation.Method. This research involves constructing a nine-variate prediction ellipsoid for data normalized using the Box-Cox transformation to improve keystroke dynamics recognition. The squared Mahalanobis distance is applied to identify and remove outliers, while the Mardia test assesses deviations from normality in the multivariate distribution. Estimates for parameters of multivariate Box-Cox transformation are derived using the maximum likelihood method.Results. The results demonstrate significant performance improvements after normalization, reaching higher accuracy and robustness compared to models built for non-normalized data. The application of the nine-variate Box-Cox transformation successfully accounted for feature correlations, enabling the prediction ellipsoid to better capture underlying data patterns.Conclusions. For keystroke dynamics recognition, a mathematical model in the form of the nine-variate prediction ellipsoid for data normalized using the multivariate Box-Cox transformation has been developed, which enhances the probability of recognition compared to models constructed for non-normalized data. However, challenges remain in determining the optimal normalization technique and selecting the significance level for constructing the prediction ellipsoid. These findings underscore the importance of careful feature selection and advanced data normalization techniques for further research in keystroke dynamics recognition.