and Domagoj Jakobovic (Faculty of Electrical Engineering and Computing, Croatia). Currently, Stjepan is working as an assistant professor at TU Delft, The Netherlands. Before that, Stjepan worked at MIT, USA and KU Leuven, Belgium. Stjepan also has several years of experience working in industry and government. He regularly publishes papers in both evolutionary computation and cryptographic conferences and journals. Besides that, he is a member of several professional societies (ACM, IEEE, IACR). Domagoj Jakobovic received his Ph.D. degree in 2005 at the University of Zagreb, Croatia, on the subject of generating scheduling heuristics with genetic programming. He is currently a full professor at the Department of Electronics, Microelectronics, Computer and Intelligent Systems at the University of Zagreb. His research interests include evolutionary algorithms, optimization methods, and parallel algorithms. Most notable contributions are in the area of a machine supported scheduling, optimization problems in cryptography, parallelization, and improvement of evolutionary algorithms. He has published more than 90 papers, lead several research projects, and serves as a reviewer for many international journals and conferences. Symmetric and Public Key Cryptosystems Symmetric key cryptosystems: The key used for encryption and decryption is the same. Alice and Bob must agree on this key before the communication takes place. Can be further classified in: Stream ciphers: Encryption and decryption process single symbols of the plaintext and the ciphertext. Block ciphers: Encryption and decryption work over blocks of fixed length of symbols. Public key (or asymmetric key) cryptosystems: The keys used for encryption and decryption differ. Alice uses Bob's public key K E to encrypt, while Bob uses his own private key K D to decrypt.