  In this paper we consider a wiretap channel with a secret key buffer. We use
the coding scheme of [1] to enhance the secrecy rate to the capacity of the
main channel, while storing each securely transmitted message in the secret key
buffer. We use the oldest secret bits from the buffer to be used as a secret
key to transmit a message in a slot and then remove those bits. With this
scheme we are able to prove stronger results than those in [1]. i.e., not only
the message which is being transmitted currently, but all the messages
transmitted in last $N_1$ slots are secure with respect to all the information
that the eavesdropper possesses, where $N_1$ can be chosen arbitrarily large.
