Detection of Timing Side-Channels in TLS

The TLS protocol is complex and widely used, which necessitates thorough testing, as there are many devices relying on it for secure communication. This thesis focuses on timing side-channel vulnerabilities, which seem to come back every few years in different variations of the same attacks. It aims to help correctly fix those vulnerabilities and prevent the creation of new ones by providing an automated side-channel testing framework that is integrated into the tlsfuzzer tool, and by expanding its test suite with test scripts for known attacks that exploit timing side-channels. The extension utilizes tcpdump for collecting the timing information and statistical tests and supporting plots to make a decision. The extension and the new test scripts were evaluated and shown to be accurate at spotting side-channels. Both the extension and the test scripts are now a part of the tlsfuzzer tool.


Faculty of Information Technology

Date of Completion




Vojnar Tomáš


Kario Hubert


Koscielniak Jan