Abstract:

SNAKE is a Feistel cipher proposed by Lee and Cha at JWISC 1997. It has two versions, i.e. SNAKE(1) and SNAKE(2). The security of the reducedround SNAKE(2) against meetinthemiddle attacks is evaluated in this paper. Attacks on 7/8/9 rounds SNAKE(2) with a 64bit block are performed. The result shows that SNAKE(2) reduced to 9 rounds is not immune to meetinthemiddle attacks. The data complexity, time complexity and precomputation complexity are 211.2,222 and  232 respectively, which implies a real world attack.

Key words: block cipher;meetinthemiddle attack；SNAKE(2)；attack complexity