Cryptography has a very long and exciting history. For centuries, political leaders and military forces have used cryptographic techniques, primarily to communicate securely. Modern cryptography is concerned with an enormous variety of scenarios where the involved parties do not fully trust each other such as internet banking, electronic voting, integrity of data, security of computer networks and many more.
This course offers an introduction to this fascinating subject. After a quick treatment of historic cryptographic schemes, we will set out the formal definitions to be able to investigate perfectly-secret and computationally-secure encryption, pseudorandomness, hash functions, and message authentication codes and block ciphers. While these primitives are referred to as symmetric-key primitives (because the involved parties use the same keys), another important class are public-key (or asymmetric) primitives which allow for public-key encryption and digital signatures. The most well-known example is the widely-used RSA system.