Cryptography

The course starts with a historical introduction to cryptography, Kerchoff´s principle and the pioneering work of Shannon and Feistel, who established the foundation for symmetric block ciphers. Following this, symmetric encryption is explored, with a focus on standards such as DES, 3DES, AES and the other contenders. Symmetric encryption is extended to yield either a stream cipher or a random number generator for key production. Drawbacks of symmetric encryption are discussed, with a focus on the key distribution problem. Asymmetric encryption is introduced as a solution to the key distribution problem, with a focus on the Diffie-Hellman and RSA algorithms. Asymmetric cryptography is applied to the issue of message authentication. Combined symmetric and asymmetric encryption is introduced as espoused by the PGP architecture. Hashing algorithms are explored, with a focus on applications in digital forensics. Cryptanalysis is discussed, including brute force attacks, differential and linear cryptanalysis and side-channel attacks. Different cryptanalytic situations are defined with respect to quantity and type of empirical data available. Blockchains and digital currencies are introduced.