Zero Correlation Cryptanalysis Of Block Cipher SPECK

SPECK is a famous lightweight block cipher algorithm de-signed by Ray Beaulieu etc. in 2013. It is composed of basic operations. The block size of SPECK is 32,48,64,96 or 128-bit, and the key length is 64,72, 96,128,144,192 or 256-bit. That is to say both the block size and the key length are varied. There are ten instances of SPECK and we can choose the suitable block size and key length according to the application environment, the requirement of security as well as performance.First, this paper introduces the SPECK block cipher. The round func-tion consists of rotations, bitwise XOR and addition in the field. And the SPECK key schedules use the round function to generate round keys. As a result, the SPECK gains an optimal performance in software. There are some cryptanalysis on SPECK already. For example, the boomerang and rectangle attacks from Farzaneh Abed, differential cryptanalysis from Alex Biryukov and the improved differential cryptanalysis from Itai Dinur. We intend to analyze the SPECK block cipher regarding to its resistance against zero correlation cryptanalysis.Zero correlation cryptanalysis is first proposed by Bogdanov and Rijmen in 2012. It is a new attack taking advantages of linear approximation with correlation zero. The linear correlation is related to the probability of linear characteristic. Due to the high data complexity, the zero correlation cryptanal-ysis was restricted and the development is slow. But in 2012, some methods were proposed to improve the zero correlation cryptanalysis, especially the da-ta complexity. They make use of the multi-dimensional distinguisher to avoid some assumptions so as to attack the block ciphers more efficiently.According to the special structure of SPECK block cipher and the theo- ry of zero correlation cryptanalysis, we find a 6-round zero correlation linear characteristic. Based on this characteristic, we describe the zero correlation cryptanalysis on 11-round SPECK 32/64 block cipher. Several counters must be counted because we need to guess many bits of the key. The time complex-ity could be controlled if the key bits were figure out in parts. The details of the attack and the complexity cryptanalysis are in this paper together with the zero correlation cryptanalysis on SPECK 48/96 block cipher.