97 research outputs found
Non-Adaptive Coding for Two-Way Wiretap Channel with or without Cost Constraints
This paper studies the secrecy results for the two-way wiretap channel
(TW-WC) with an external eavesdropper under a strong secrecy metric. Employing
non-adaptive coding, we analyze the information leakage and the decoding error
probability, and derive inner bounds on the secrecy capacity regions for the
TW-WC under strong joint and individual secrecy constraints. For the TW-WC
without cost constraint, both the secrecy and error exponents could be
characterized by the conditional R\'enyi mutual information in a concise and
compact form. And, some special cases secrecy capacity region and sum-rate
capacity results are established, demonstrating that adaption is useless in
some cases or the maximum sum-rate that could be achieved by non-adaptive
coding. For the TW-WC with cost constraint, we consider the peak cost
constraint and extend our secrecy results by using the constant composition
codes. Accordingly, we characterize both the secrecy and error exponents by a
modification of R\'enyi mutual information, which yields inner bounds on the
secrecy capacity regions for the general discrete memoryless TW-WC with cost
constraint. Our method works even when a pre-noisy processing is employed based
on a conditional distribution in the encoder and can be easily extended to
other multi-user communication scenarios
Scalable Group Secret Key Generation over Wireless Channels
In this paper, we consider the problem of secret key generation for multiple
parties. Multi-user networks usually require a trusted party to efficiently
distribute keys to the legitimate users and this process is a weakness against
eavesdroppers. With the help of the physical layer security techniques, users
can securely decide on a secret key without a trusted party by exploiting the
unique properties of the channel. In this context, we develop a physical layer
group key generation scheme that is also based on the ideas of the analog
function computation studies. We firstly consider the key generation as a
function to be computed over the wireless channel and propose two novel methods
depending on the users transmission capability (i.e. half-duplex and
full-duplex transmissions). Secondly, we exploit the uniqueness of the prime
integers in order to enable the simultaneous transmission of the users for key
generation. As a result, our approach contributes to the scalability of the
existing physical layer key generation algorithms since all users transmit
simultaneously rather than using pairwise communications. We prove that our
half-duplex network model reduces the required number of communications for
group key generation down to a linear scale. Furthermore, the full-duplex
network model reduces to a constant scale.Comment: 7 pages, 3 figure, transaction
The Secrecy Capacity of The Gaussian Wiretap Channel with Rate-Limited Help
The Gaussian wiretap channel with rate-limited help, available at the
legitimate receiver (Rx) or/and transmitter (Tx), is studied under various
channel configurations (degraded, reversely degraded and non-degraded). In the
case of Rx help and all channel configurations, the rate-limited help results
in a secrecy capacity boost equal to the help rate irrespective of whether the
help is secure or not, so that the secrecy of help does not provide any
capacity increase. The secrecy capacity is positive for the reversely-degraded
channel (where the no-help secrecy capacity is zero) and no wiretap coding is
needed to achieve it. More noise at the legitimate receiver can sometimes
result in higher secrecy capacity. The secrecy capacity with Rx help is not
increased even if the helper is aware of the message being transmitted. The
same secrecy capacity boost also holds if non-secure help is available to the
transmitter (encoder), in addition to or instead of the same Rx help, so that,
in the case of the joint Tx/Rx help, one help link can be omitted without
affecting the capacity. If Rx/Tx help links are independent of each other, then
the boost in the secrecy capacity is the sum of help rates and no link can be
omitted without a loss in the capacity. Non-singular correlation of the
receiver and eavesdropper noises does not affect the secrecy capacity and
non-causal help does not bring in any capacity increase over the causal one.Comment: An extended version of the paper presented at the IEEE International
Symposium on Information Theory, Helsinki, Finland, June 26 - July 1, 2022;
submitted to IEEE Trans. Info. Theor
Achievable Region of the K-User MAC Wiretap Channel Under Strong Secrecy
This paper investigates the information-theoretic secrecy problem for a K-user discrete memoryless (DM) multiple-access wiretap (MAC-WT) channel. Instead of using the weak secrecy criterion characterized by information leakage rate, we adopt the strong secrecy metric defined by information leakage to better protect the confidential information. We provide an achievable rate region and prove its achievability by providing a coding scheme and analyzing the output statistics in terms of (average) variational distance. We show that the rate region obtained in previous works on the subject is a special case of ours. We also show that the achievability proof in such works is incomplete, because it is assumed that certain inequalities hold while they may not in some cases. We solve this problem by constructing an inequality structure for the rates of all users' secret and redundant messages, and analyzing the conditions required to maintain this structure
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