Multi-terminal Secrecy in a Linear Non-coherent Packetized Networks
This work addresses secure communication in multi-terminal networks, providing theoretical bounds that are incremental to existing secrecy capacity results.
The paper tackles the problem of generating a shared secret key among multiple trusted nodes over a network with a passive eavesdropper, using a linear non-coherent network coding broadcast channel and a public channel. It proposes upper and lower bounds for the secret key generation capacity in the large field size regime, achieving a complete characterization for the case of two trusted terminals.
We consider a group of m+1 trusted nodes that aim to create a shared secret key K over a network in the presence of a passive eavesdropper, Eve. We assume a linear non-coherent network coding broadcast channel (over a finite field F_q) from one of the honest nodes (i.e., Alice) to the rest of them including Eve. All of the trusted nodes can also discuss over a cost-free public channel which is also overheard by Eve. For this setup, we propose upper and lower bounds for the secret key generation capacity assuming that the field size q is very large. For the case of two trusted terminals (m = 1) our upper and lower bounds match and we have complete characterization for the secrecy capacity in the large field size regime.