Information-Theoretical Security for Several Models of Multiple-Access Channel

Several security models of Multiple-Access Channel (MAC) are investigated. The authors study the degraded MAC with confidential messages, where two users transmit their confidential messages (no common message) to a destination, and each user obtains a degraded version of the output of the MAC. Each user views the other user as a eavesdropper, and wishes to keep its confidential message as secret as possible from the other user. Measuring each user's uncertainty about the other user's confidential message by equivocation, the capacity-equivocation region for this model has been determined. The result is further explained via the binary and Gaussian examples.