The autocorrelation properties of single cycle polynomial T-functions

T-functions have been widely used in the design of symmetric ciphers, hash functions, and fast cryptographic primitives. Single cycle polynomial T-functions are a special category. If they are used as state transition functions of stream ciphers, the security of the generated sequences is crucial. In 2008, Kolokotronis proposed a conjecture regarding the autocorrelation function’s values of coordinate sequences generated by single cycle polynomial T-functions. In this paper, we show that the conjecture does not hold in general and prove the conditions under which it holds.