  It is claimed in the many papers that a trace distance ($d$) guarantees the
universal composition security in quantum key distribution (QKD). In this
introduction paper, at first, it is explicitly explained what is the main
misconception in the claim of the unconditional security for QKD theory. In
general terms, the cause of the misunderstanding on the security claim is the
Lemma in the paper of Renner. It suggests that the generation of the perfect
random key is assured by the probability $ (1-d)$, and its failure probability
is $d$. Thus, it concludes that the generated key provides the perfect random
key sequence when the protocol suceeds. So the QKD provides perfect secrecy to
the one time pad. This is the reason for the composition claim. However, the
quantity of the trace distance (or variational distance) is not the probability
for such an event. If $d $ is not small enough, always the generated key
sequence is not uniform. Now one needs the reconstruction of the evaluation of
the trace distance if one wants to use it. One should first go back to the
indistinguishability theory in the computational complexity based, and to
clarify the meaning of the value of the variational distance. In addition, the
same analysis for the information theoretic case is necessary. The recent
serial papers by H.P.Yuen have given the answer on such questions. In this
paper, we show more concise description of Yuen's theory, and clarify that the
recent upper bound theories for the trace distance by Tomamichel et al and
Hayashi et al are constructed based on the reasoning of Renner and it is
unsuitable as the analysis for information theoretic security. Finally, we
introduce a macroscopic quantum communication with different principle to
replace Q-bit QKD.
