Wiretap Channel with Information Embedding on Actions

Abstract

Information embedding on actions is a new channel model in which a specific decoder is used to observe the actions taken by the encoder and retrieve part of the message intended for the receiver. We revisit this model and consider a different scenario where a secrecy constraint is imposed. By adding a wiretapper in the model, we aim to send the confidential message to the receiver and keep it secret from the wiretapper as much as possible. We characterize the inner and outer bounds on the capacity-equivocation region of such a channel with noncausal (and causal) channel state information. Furthermore, the lower and upper bounds on the sum secrecy capacity are also obtained. Besides, by eliminating the specific decoder, we get a new outer bound on the capacity-equivocation region of the wiretap channel with action-dependent states and prove it is tighter than the existing outer bound. A binary example is presented to illustrate the tradeoff between the sum secrecy rate and the information embedding rate under the secrecy constraint. We find that the secrecy constraint and the communication requirements of information embedding have a negative impact on improving the secrecy transmission rate of the given communication link.

Wiretap Channel with Rate-Limited Channel State Information

“…Liu and Chen got a lower bound on the secrecy capacity of the model where CSI was available noncausally at both the encoder and the decoder [11], and an upper bound was established by [12]. Action-dependent channel models involving secrecy were studied in [13][14][15]. Dai et al provided the inner and outer bounds on the capacity-equivocation region for the wiretap channel with action-dependent states [13].…”

“…The above statedependent channel models [1][2][3][4][5][6][7] considered no secrecy constraint. Recently, the works [8][9][10][11][12][13][14][15] have introduced the wiretapper in channels with CSI to model a safe communication model. Chen and Vinck explored the discrete memoryless wiretap channel with noncausal CSI and presented an achievable rate-equivocation region [8].…”

“…We restricted the rate of the feedback by introducing a rate-limited feedback link and obtained the corresponding capacity-equivocation region. Then, we explored information embedding on the actions in wiretap channel where part of the message was embedded on the actions [15] and characterized the tradeoff between the sum secrecy rate and the information embedding rate.…”