In cryptology we commonly face the problem of finding an unknown key K from the output of an interactable keyed function F(V, K). The input parameter V is a publicly controllable value which makes F interactable in the sense that an oracle  provides the adversary with the output value of the function for any V of her choice and for any fixed random key. The goal of the adversary is to recover K as efficiently as possible. This talk gives an overview of the recent works done in this direction by Vielhaber [eprint'07], Fischer-Khazaei-Meier [Africacrypt'08], Dinur-Shamir [eprint'08] and Khazaei-Meier [Indocrypt'08]. In particular apply the method to Klomov-Shamir's T-function based self-synchronizing stream cipher.