An Improved Automatic Search Method for Differential Trails in TEA Cipher

TEA (Tiny Encryption Algorithm) is a block cipher with simple ARX (addition, rotation, exclusive-OR) based Feistel network, designed for both hardware and software scenario. Inspired by the auto search algorithm for ARX cipher introduced by Biryukov and Velichkov in 2014, we proposed an improved version of auto search algorithm for ARX cipher and verified in block cipher TEA. By introducing a sorted partial difference distribution table (sorted pDDT), our algorithm can eliminate lots of branches in advance during differential trail search phase. As time of the search algorithm increase exponentially with the rounds increasing, our algorithm make a great improvement in the search performance.