This paper studies secrecy capacity in a semi-deterministic setting, in which the channel between legitimate users (called Alice and Bob) is deterministic, while that between Alice and the eavesdropper (called Eve) is a discrete memoryless channel. Such a model is particularly relevant when a pre-existing error correcting code tailored to the legitimate channel is in use on top of which secret information is to be shared. First, a point-to-point setting is considered with a single wiretapper, a situation in which the secrecy capacity has an elegant characterization. Next, a generalized multiple access setting with confidential messages is considered in which each user wishes to communicate secret information to a common destination without the other determining its message. In this latter situation, outer bounds on the secrecy capacity are obtained.
This paper studies secrecy capacity in a semi-deterministic setting, in which the channel between legitimate users (called Alice and Bob) is deterministic, while that between Alice and the eavesdropper (called Eve) is a discrete memoryless channel. Such a model is particularly relevant when a pre-existing error correcting code tailored to the legitimate channel is in use on top of which secret information is to be shared. First, a point-to-point setting is considered with a single wiretapper, a situation in which the secrecy capacity has an elegant characterization. Next, a generalized multiple access setting with confidential messages is considered in which each user wishes to communicate secret information to a common destination without the other determining its message. In this latter situation, outer bounds on the secrecy capacity are obtained.
In this paper, we study the problem of secret communication over a Multiple Access Wire-tap Channel with Common Message. Here, we assume that two transmitters have confidential messages which must be kept secret from the eavesdropper (the second receiver), and both of them have access to a common message which can be decoded by two receivers. For this setting, we derive general inner and outer bounds on the secrecy capacity region for the discrete memoryless case as well as for Gaussian one. Providing numerical examples for the Gaussian case, we illustrate the comparison between derived achievable rate regions and outer bounds for our considered model and the capacity region of compound multiple access channel.
In this paper, we study the problem of secret communication over a Multiple Access Wire-tap Channel with Common Message. In this channel, we assume that two transmitters have confidential messages which must be kept secret from the eavesdropper (receiver 2), and both of them have a common message which can be decoded by two receivers. For this setting, in the discrete memoryless case we derive general inner and outer bounds on the secrecy capacity region. Also, we derive inner and outer bounds on the secrecy capacity region for the Gaussian case. Providing numerical examples for the Gaussian case, we illustrate the comparison between derived achievable rate regions, outer bounds and the capacity region of compound multiple access channel.
A discrete memoryless multiple-access channel (MAC) with confidential messages is studied, where two users attempt to transmit common information to a destination and each user also has private (confidential) information intended for the destination. This channel generalizes the classical MAC model in that each user also receives channel outputs, and hence may obtain the confidential information sent by the other user from the channel output it receives. However, each user views the other user as a wiretapper or eavesdropper, and wishes to keep its confidential information as secret as possible from the other user. The level of secrecy of the confidential information is measured by the equivocation rate, i.e., the entropy rate of the confidential information conditioned on channel outputs at the wiretapper (the other user). The performance measure is the rate-equivocation tuple that includes the common rate, two private rates, and two equivocation rates as components. The set that includes all achievable rate-equivocation tuples is referred to as the capacity-equivocation region. The case of perfect secrecy is particularly of interest, in which each user's confidential information is perfectly hidden from the other user. The set that includes all achievable rates with perfect secrecy is referred to as the secrecy capacity region. For the MAC with two confidential messages, in which both users have confidential messages for the destination, inner bounds on the capacity-equivocation region, and secrecy capacity region are obtained. It is demonstrated that there is a tradeoff between the two equivocation rates (secrecy levels) achieved for the two confidential messages. For the MAC with one confidential message, in which only one user (user 1) has private (confidential) information for the destination, inner and outer bounds on the capacity-equivocation region are derived. These bounds match partially, and hence the capacity-equivocation region is partially characterized. Furthermore, the outer bound provides a tight converse for the case of perfect secrecy, and hence establishes the secrecy capacity region. A class of degraded MACs with one confidential message is further studied, and the capacity-equivocation region and the secrecy capacity region are established. These results are further explored via two example channels: the binary and Gaussian MACs. For both channels, the capacity-equivocation regions and the secrecy capacity regions are obtained.
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.
In this study, we obtain an outer bound on the secrecy capacity region of a two-user semi-deterministic discrete memoryless broadcast channel with considering side-information available at the transmitter, where, the sender contain two independent confidential messages, each one is deliberated for one of the receivers but is kept entirely secret from the other. Further, we compare obtained outer bound via the specified secrecy capacity outer bound of the semi-deterministic broadcast channel without side information and without secrecy constraint; specifically, the side information impact on the outer bound is explained.
Two-user Multiple Access Channel with a Wire-Tapper (MAC-WT) is considered. A general outer bound for the secrecy capacity region is given. Also, we have defined the Deterministic MAC-WT, where the channel input of each user is a deterministic function of the channel output and the channel input of the other user. For this network single-letter inner and outer bounds for the secrecy capacity region are given. Furthermore, it is shown that in the Deterministic MAC-WT, if the wiretapper channel is a degraded version of the main channel, inner and outer bounds meet and the secrecy capacity region is characterized.