On mixing properties of register transformations of ciphers TEA1 and TEA2

In 2023, stream ciphers TEA1, TEA2, TEA3 were revealed as a part of TETRA standard. We study the mixing properties of register transformations of stream ciphers TEA1 and TEA2. Using the matrix-graph approach, we have calculated the exponents of these register transformations’ mixing matrices, it is equal to 6 and 34 respectively. As a result, we can conclude that the calculated exponents for TEA1 and TEA2 are fitting the parameters chosen by developers. Moreover, it is possible to use key registers with lesser number of warm-up rounds for lightweight ciphers implementation.