Assume you are a member of the FarmEye project team that develops an all$-$weather

IP$-$enabled $($IoT$)$ CCTV camera system to monitor farm buildings and farm yards.

The product is aimed to tackle the growing problem of farm theft and farm

trespassing. The target market are both farmers and security services.

The camera provides a $24/7$ life stream, with an uncompressed RGB still image being

sent every second. Data communication is provided via a proprietary radio link to a

nearby Internet$-$enabled base station, so an end$-$to$-$end encryption of the captured

images between camera and base station is required. However, the computational

resources on the camera are limited$,$ therefore none of the standard L$2/$L$3/$L$4$ security

protocols can be adopted. Instead you are asked to provide a secure data

communication protocol that streams data from a single camera to the base station.

a$)$ Identify concrete possible active and passive attacks by a threat actor on the radio

data communication link. Based on these, outline the requirements for a secure

communication protocol.

$[4$ marks$]$

b$)$ Based on your findings in a$)$ devise a simple protocol message format that allows

the streaming of data from the camera to the base station. Justify your design.

$[3$ marks$]$

c$)$ Version $1$ of the communication protocol uses a private key block cipher, with the

key shared between the camera and the base station. Show how a simple algorithm

can be implemented via a Feistel cipher.

$[5$ marks$]$

d$)$ Determine if your image encryption should be done in EBC mode or in CBC

mode. Distinguish between both modes of operation, and justify your decision.

$[3$ marks$]$

e$)$ Version $2$ of the protocol uses a stream cipher instead of a block cipher. Using an

example explain how such a stream cipher based on an LFSR could be

implemented, and show how the encoding and decoding process works.

$[5$ marks$]$

f$)$ Determine how your protocol would benefit from an additional hash function

complementary to either version $1$ or version $2,$ and subsequently update your

design. Outline how this extension increases the robustness of your protocol.

$[4$ marks$]$

g$)$ In order to simplify key management it is suggested to integrate the DiffieHellman key exchange protocol. Using an example, show how a key exchange

between the camera and the base station could be accomplished. Further on$,$

comment on the security $/$ robustness of this extension and, using an example,

show how a threat actor could compromise the key exchange.

$[6$ marks$]$