Improvement on Bit Diffusion Analysis of π-Cipher

Abstract π-Cipher, designed by Gligoroski et al., is a second round candidate of the CAESAR competition. The designers analyzed the bit diffusion of the cipher by examining the * operation and 1 round π-function. We improve this analysis by applying Strict Avalanche Criterion (SAC) test to * operation and reduced round versions of π-function for π 16-Cipher. We found out that * operation fails SAC test whereas all versions of π-function for π 16-Cipher pass the test.