(Created 2008-07-17.)

CRYPTOGRAPHY | EDI051 |

**Aim**

This course is intended to be an introduction to the fascinating subject of cryptography. It provides both a firm ground in the fundamentals and a feel for the subject for anyone interested either in carrying out cryptographic research or employing cryptographic security.

*Knowledge and understanding*

For a passing grade the student must

- be able to describe different building blocks used in cryptology,
- be able to describe the general problems that are addressed by cryptology,
- be able to explain the principles behind different cryptographic primitives.

*Skills and abilities*

For a passing grade the student must

- be able to provide descriptions of how cryptographic primitives can be used in security systems.
- be able to show that you are capable to choose suitable parameters to cryptographic primitives as well as analyze various constructions from a security perspective.

**Contents***Classical cryptography*: Introduction and basic notation, The Caesar cipher, simple substitution, polyalphabetic ciphers (Vigenére, Kasiskis method, Vernam), transposition ciphers, rotor machines (Enigma).

*Shannons theory of secrecy*: entropy, key and message equivocation, redundancy, unicity distance, perfect secrecy.

*Shift register theory and stream ciphers*: Finite fields, linear feedback shift register sequences, periods and cycle sets, shift register synthesis, nonlinear combinations of sequences, attacks on stream ciphers.

*Block ciphers*: Data Encryption Standard (DES), Advanced Encryption Standard (AES).

*Public key cryptography*: Basic number theory, RSA, Diffie-Hellman key exchange, factoring, primality, digital signatures.

*Authentication codes*: Impersonation and substitution attacks.

S*ecret sharing*: Shamirs threshold scheme, general secret sharing, perfect and ideal schemes.

*Projects*: 1. Factoring. 2. Correlation attacks. 3. Shift register sequences. 4. Block ciphers.

**Literature**

Lecture notes in cryptology (distributed through the department).

Alternative literature: Stinson, D., Cryptography, Theory and Practice, CRC Press, ISBN 1-58488-206-9 or Smart, N., Cryptography: An Introduction, McGraw-Hill, ISBN 0077099877.