Design and Evaluation of Decision Making Algorithms for Information Security
Journal : Ph. D. Thesis
October 24, 2025
The evaluation and learning of classifiers is of particular importance in several computer security applications such as intrusion detection systems (IDSs), spam filters, and watermarking of documents for fingerprinting or traitor tracing. There are however relevant considerations that are sometimes ignored by researchers that apply machine learning techniques for security related problems. In this work we identify and work on two problems that seem prevalent in security-related applications. The first problem is the usually large class imbalance between normal events and attack events. We address this problem with a unifying view of different proposed metrics, and with the introduction of Bayesian Receiver Operating Characteristic (BROC) curves. The second problem to consider is the fact that the classifier or learning rule will be deployed in an adversarial environment. This implies that good performance on average might not be a good performance measure, but rather we look for good performance under the worst type of adversarial attacks. We work on a general methodology that we apply for the design and evaluation of IDSs and Watermarking applications.