Distinguishing Attacks on T-Functions

Klimov and Shamir proposed a new class of simple cryptographic primitives named T-functions. For two concrete proposals based on the squaring operation, a single word T-function and a previously unbroken multi-word T-function with a 256-bit state, we describe an efficient distinguishing attack having a 232 data complexity. Furthermore, Hong et al. recently proposed two fully specified stream ciphers, consisting of multi-word T-functions with 128-bit states and filtering functions. We describe distinguishing attacks having a 222 and a 234 data complexity, respectively. The attacks have been implemented. Key words Stream cipher, T-function, square mapping, distinguishing attack, statistical cryptanalysis

• Type: Conference
• Year: 2005
• Where: MYCRYPT
• Authors: Simon Künzli 0002, Pascal Junod, Willi Meier
• Keywords: Cryptology, Distinguishing Attack, Multi-word T-functions, MYCRYPT 2005, Stream Cipher