Consider the following block cipher mode for encryption applied to a PRP

F with block length n$.$ Is it CPA$-$secure$?$ If yes, give a proof. If no$,$ then

describe a distinguisher and compute its advantage.

Enc$($k$,$ m$1||||$m$`)$:

c$0\{0,1\}$

n

r$0$ :$=$ c$0$

for i $=1$ to $`$ :

ri

:$=$ ri$1$ mi

ci

:$=$ Fk$($ri$)$

return c$0||||$c$`$

proof with mathematically not theoritically.