10.18453/rosdok_id00002900 Kölsch, Lukas Lukas Kölsch http://d-nb.info/gnd/1225141133 Universität Rostock 2020 510 Mathematics 2020 en http://purl.uni-rostock.de/rosdok/id00002900 urn:nbn:de:gbv:28-rosdok_id00002900-8 Block ciphers constitute a major part of modern symmetric cryptography. A mathematical analysis is necessary to ensure the security of the cipher. In this thesis, I develop several new contributions for the analysis of block ciphers. I determine cryptographic properties of several special cryptographically interesting mappings like almost perfect nonlinear functions. I also give some new results both on the resistance of functions against differential-linear attacks as well as on the efficiency of implementation of certain block ciphers.