by Sena, Rie, Miki and Kana from AIKATSU☆STARS and "MUSIC OF DREAM!" by Sena, Rie, Miki and Kana from AIKATSU☆STARS, while the ending themes are "Episode Solo" by Ruka, Nanase, Kana, and Miho from AIKATSU☆STARS, "So Beautiful Story" by Ruka and Sena from AIKATSU☆STARS, "Bon Bon Voyage!" by Risa and Miho from AIKATSU☆STARS and "Pirouette Of The Forest Light" by Ruka and Sena from AIKATSU☆STARS. Many of the songs were composed and arranged by Monaca, and performed by members of the Japanese idol group AIKATSU☆STARS who provide the singing voices for the characters. Some of the insert songs are the theme songs but sung by different members from the opening or closing. The songs have been compiled into several albums. Hybrid argument (Cryptography)  In cryptography, the hybrid argument is a proof technique used to show that two distributions are computationally indistinguishable. Formally, to show two distributions "D"1 and "D"2 are computationally indistinguishable, we can define a sequence of "hybrid distributions" "D"1 := "H"0, "H"1, ..., "H""t" =: "D"2 where "t" is polynomial in the security parameter. Define the advantage of any probabilistic efficient (polynomial-bounded time) algorithm A as  where the dollar symbol ($) denotes that we sample an element from the distribution at random. By triangle inequality, it is clear that for any probabilistic polynomial time algorithm A,  Thus there must exist some "k" s.t. 0 ≤ "k" < "t" and  Since "t" is polynomial-bounded, for any such algorithm A, if we can show that its advantage to distinguish the distributions "H""i" and "H""i"+1 is negligible for every "i", then it immediately follows that its advantage to distinguish the distributions "D""1" = "H"0 and "D""2" = "H""t" must also be negligible. This fact gives rise to the hybrid argument: it suffices to find such a sequence of hybrid distributions and show each pair of them is computationally indistinguishable.