Research Area: CyberSecurity
In the first part of the dissertation, we deal with fault-based attack son cryptographic circuits which belong to the field of active implementation attacks and aim to retrieve secret keys stored on such chips. Our main focus lies on the crypt analytic aspects of those attacks. In particular, we target block ciphers with a lightweight and (often) non-bijection schedule where the derived sub keys are (almost) independent from each other. An attacker who is able to reconstruct one of the sub keys is thus not necessarily able to directly retrieve other sub keys or even the secret master key by simply reversing the key schedule.
We introduce a framework based on differential fault analysis that allows to attack block ciphers with an arbitrary number of independent sub keys and which rely on a substitution-permutation network. These methods are then applied to the lightweight block ciphers LED and PRINCE and we show in both cases how to recover the secret master key requiring only a small number of fault injections. Moreover, we investigate approaches that utilize algebraic instead of differential techniques for the fault analysis and discuss advantages and drawback.
In the second part of the thesis, we focus on authenticated encryption schemes. While regular ciphers only protect privacy of processed data, authenticated encryption schemes also secure its authenticity and integrity. Many of these ciphers are additionally able to protect authenticity and integrity of so-called associated data. This type of data is transmitted unencrypted but nevertheless must be protected from being tampered with during transmission.
Name of the Researcher: Philipp Jovanovic
Name of the Supervisor(s): Martin Kreuzer
Year of Completion: 2015
University: University of Passau
Thesis Link: Home Page Url
