Breaching Security of Full Round Tiny Encryption Algorithm

Tiny encryption algorithm is a 64-bit block cipher designed by Wheeler and Needham in 1994 and attracted much of its attention due to its capability of reducing the hardware cost. In this paper, we introduced coincidence count attack at bit level, a kind of known-plaintext attack and evaluated the resistance of TEA to withstand with it. We also examined confrontation of full round TEA against bit sum attack. Furthermore, we introduced a modest algorithm based on coincidence count and bit sum concept that makes it easy to find relevant plaintext corresponding to an arbitrary cipher text with a probability of 0.93. We also presented how cipher text originated from tiny encryption algorithm can be distinguished from a random permutation of binary sequence.