Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two-hop Secure Communication Using an Untrusted Relay   We consider a source-destination pair that can only communicate through an
untrusted intermediate relay node. The intermediate node is willing to employ a
designated relaying scheme to facilitate reliable communication between the
source and the destination. Yet, the information it relays needs to be kept
secret from it. In this two-hop communication scenario, where the use of the
untrusted relay node is essential, we find that a positive secrecy rate is
achievable. The center piece of the achievability scheme is the help provided
by either the destination node with transmission capability, or an external
"good samaritan" node. In either case, the helper performs cooperative jamming
that confuses the eavesdropping relay and disables it from being able to
decipher what it is relaying. We next derive an upper bound on the secrecy rate
for this system. We observe that the gap between the upper bound and the
achievable rate vanishes as the power of the relay node goes to infinity.
Overall, the paper presents a case for intentional interference, i.e.,
cooperative jamming, as an enabler for secure communication.

13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex