There are many aspects of modern technologies that are transparently applied and should make us feel safe in our everyday use of Internet. Many users do not feel threatened, since they consider their data to be unimportant to others. But what about account hijacking, ransomware, etc. Do we understand how cryptographic algorithms work? Are we aware of the directions from which attacks could be launched? Which algorithms can be considered safe at the moment? These and other questions will be answered through examples from ancient to modern cryptographic algorithms and the evolution of both cryptography and cryptanalysis.