Block cipher algorithms are commonly used to secure confidential information in everyday user applications like smart cards. However, it is quite common for ignorant users to use familiar dictionary words or even names as their personal passwords. Two optimisation heuristic cryptanalytic attack methods (Tabu Search and Genetic Algorithm) are used to conduct intelligent keysearch attacks on classical ciphers and modern ciphers. The classical ciphers examined are the Hill Cipher (a substitution cipher) and the Columnar Transposition Cipher (a permutation / transposition cipher). The algorithm chosen to represent modern block ciphers is the Advanced Encryption Standard (AES) algorithm (also known as ?Rijndael?). Find out how a password encrypted with AES can be broken within a few hours!