Improved 3-dimensional meet-in-the-middle cryptanalysis of KTANTAN32

A 3-dimensional meet-in-the-middle (3D-MITM) attack on block cipher KTANTAN32 was proposed, which divided the algorithm to three segments by guessing two certain intermediate states and applied meet-in-the-middle attack on each segment respectively. This attack worked with a time complexity 2^67.63 in terms of full round encryptions and used only 3 plaintext/ciphertext pairs. Furthermore, KTANTAN32 could be broken with a time complexity of 2^65.17 if combining 3D-MITM attack with data preprocessing and caching techniques, which avoided the repetition calculation. The results provided a general method for analyzing the security of other block ciphers by 3D-MITM attack.