You are required to develop a block cypher scheme for a healthcare company to deal with the

message encryption for communication from doctors to patients. This system requires the use

of keys and a sequenced based cipher mode.

$[10\%]$

$[10\%]$

$[10\%]$

$($a$)$ Draw a schematic of the block cipher system using all the two components discussed

above $($keys and a sequenced based cipher mode$).$ Comment on your design creating a

justification for the method you created.

$($b$)$ Describe two choices of different cipher encryption modes and key sizes for secure

communications.

$($c$)$ Describe a set of vulnerabilities with the sequenced encryption modes and the possible

benefits of random$-$access cipher encryption modes.