Thesis from 2012 in the field of Computer Science - IT Security, Grade: 1.0, University of Applied Sciences Bielefeld, Language: German. Abstract: For millennia, people have encrypted messages to keep them secret from others. Over the years, there has been an ongoing competition between cryptologists and cryptanalysts - the former to develop a supposedly secure method, the latter to break those methods. This paper provides an insight into the most significant representatives of classical and modern cryptography and cryptanalysis.