Leading-edge Cryptography

Cryptography, a fundamental information security technology, is used in diverse aspects of daily life including digital TV broadcasting, digital money, and mobile phones. It is no exaggeration to say that the history of cryptography is the history of cryptanalysis. Even ciphers said to be absolutely safe have eventually become exposed to risks (become compromised) due to the discovery of new cryptanalysis methods or rapid advances in computers and networks, which has led, in turn, to the development of new encryption techniques. This paper describes recent developments in cryptography with a focus on activities at Fujitsu Laboratories. It also introduces technology for correctly determining the lifetime of a cipher considering advances in cryptanalysis and a new encryption technique having novel functions not found in conventional ciphers. Finally, it explains quantum cryptography, which is said to be the ultimate unbreakable cipher.