kerckhoffs\' principle states

a one ought to design systems under the assumption that the enemy will exploit the insider threat.

b one ought to design systems under the assumption that the enemy will compromise the system

c one ought to design systems under the assumption that the enemy will gain secrets

d one ought to design systems under the assumption that the enemy will gain full familiarity with them

e one ought to design systems under the assumption that the enemy will gain full administrative privileges over them