Prof. dr. ir. Bart Preneel
Professor Bart Preneel of KU Leuven heads the COSIC (COmputer Security and Industrial Cryptography) research group. His main research area is information security with a focus on cryptographic algorithms and protocols as well as their applications to both computer and network security, and mobile communications.
Stream ciphers, block ciphers and hash functions are the three classical types of symmetric algorithms.
A stream cipher generates a keystream of random bits which are exclusive-or'ed with the plaintext. Stream ciphers are often used to provide confidentiality for real-time traffic, such as GSM and Bluetooth.
Hash functions accept input strings of arbitrary length and produce fixed-length output. A Manipulation Detection Code (MDC) affords integrity protection. Given an output of an MDC, it is infeasible to find the corresponding input and it should be difficult to find colliding inputs. Practical examples are SHA-1, SHA-256 and RIPEMD-160.
A Message Authentication Code (MAC) is a hash function with a secret key that provides data origin authentication. Practical examples are CBC-MAC, based on triple-DES and AES block ciphers.