Research On Impossible Differential Cryptanalysis And Meet-in-the-middle Cryptanalysis Of Some Block Ciphers

Compared with the other ciphers, the block cipher obtains a lot of advantages like high speed of encryption, easy to standardization and adapt to various platforms, which is widely applied in network communications, message authentication, key management and so on. So research on block cipher is always a hotspot in cryptography and information security.In this dissertation, we first study the impossbile differential attack on two well-known block ciphers-ARIA and 3D. Considering on some shortcomings in impossbile differential attack, we analyze the security of MISTY1 against Meet-in-the-Middle attack. The main works are as follows:1. By exploiting the structure of ARIA and some properties in diffusion unit, a new impossible differential attack on 7 rounds of the ARIA cipher is presented. By this attack, 7-round ARIA-192 is breakable, and the complexity of the ARIA-256 can be reduce to 192.22.2. Some 6-round impossible differential distinguishers of 3D cipher are created, and hence extended to breakable 11-round 3D cipher based on these distinguishers. The technique of precomputation is widely applied, which offers a meaningful reference both on the actual attack of block cipher and to enhancement of efficient computation process.3. By exploiting some interesting properties of the key-dependent layer, we present the first meet-in-the-middle attack on the full MISTY1, with data complexities as few as 1 known plaintext in single-key setting, which offers a meaningful reference on design of a block cipher.