The Rabbit Stream Cipher - Design and Security Analysis
The stream cipher Rabbit was rst presented at FSE 2003 . In the paper at hand, a full security analysis of Rabbit is given, focusing on algebraic attacks, approximations and dierential analysis. We determine the algebraic normal form of the main nonlinear parts of the cipher as part of a comprehensive algebraic analysis. In addition, both linear and nonlinear approximations of the next-state function are presented, as well as a differential analysis of the IV-setup function. None of the investigations have revealed any exploitable weaknesses. Rabbit is characterized by high performance in software with a measured encryption/decryption speed of 3.7 clock cycles per byte on a Pentium III processor.