  It is known that a message can be transmitted safely against any wiretapper
via a noisy channel without a secret key if the coding rate is less than the
so-called secrecy capacity $C_S$, which is usually smaller than the channel
capacity $C$. In order to remove the loss $C - C_S$, we propose a multiplex
coding scheme with plural independent messages. In this paper, it is shown that
the proposed multiplex coding scheme can attain the channel capacity as the
total rate of the plural messages and the perfect secrecy for each message. The
coding theorem is proved by extending Hayashi's proof, in which the coding of
the channel resolvability is applied to wiretap channels.
