Achieving Shannon Capacity in a Wiretap Channel via Previous Messages
This work addresses security in communication systems, specifically for scenarios requiring protection against eavesdropping, and is incremental as it builds upon and strengthens previous results.
The paper tackles the problem of enhancing secrecy in a wiretap channel with a secret key buffer, achieving the capacity of the main channel while ensuring that all messages transmitted in the last N1 slots are secure against eavesdroppers, with N1 being arbitrarily large.
In this paper we consider a wiretap channel with a secret key buffer. We use the coding scheme of [1] to enhance the secrecy rate to the capacity of the main channel, while storing each securely transmitted message in the secret key buffer. We use the oldest secret bits from the buffer to be used as a secret key to transmit a message in a slot and then remove those bits. With this scheme we are able to prove stronger results than those in [1]. i.e., not only the message which is being transmitted currently, but all the messages transmitted in last $N_1$ slots are secure with respect to all the information that the eavesdropper possesses, where $N_1$ can be chosen arbitrarily large.