  This paper investigates the capacity region of a discrete memoryless (DM)
multiple access wiretap (MAC-WT) channel where, besides confidential messages,
the users have also open messages to transmit. All these messages are intended
for the legitimate receiver but only the confidential messages need to be
protected from the eavesdropper. By using random coding, we find an achievable
secrecy rate region, within which perfect secrecy can be realized, i.e., all
users can communicate with the legitimate receiver with arbitrarily small
probability of error, while the confidential information leaked to the
eavesdropper tends to zero.
