▁computational ▁resources . ▁Such ▁a ▁crypt os ystem ▁would ▁have ▁information - the or etic ▁but ▁not ▁perfect ▁security . ▁The ▁exact ▁definition ▁of ▁security ▁would ▁depend ▁on ▁the ▁crypt os ystem ▁in ▁question ▁but ▁normally ▁is ▁defined ▁as ▁a ▁bounded ▁amount ▁of ▁le aked ▁bits : ▁ ▁Here , ▁ ▁should ▁be ▁less ▁than ▁the ▁entropy ▁( number ▁of ▁bits ▁of ▁information ) ▁of ▁m , ▁otherwise ▁the ▁bound ▁is ▁trivial . ▁ ▁Un cond itional ▁security ▁ ▁The ▁term ▁information - the or etic ▁security ▁is ▁often ▁used ▁inter change ably ▁with ▁the ▁term ▁un cond itional ▁security . ▁The ▁latter ▁term ▁can ▁also ▁refer ▁to ▁systems ▁that ▁do ▁not ▁rely ▁on ▁un pro ven ▁computational ▁hard ness ▁assumptions . ▁Today , ▁such ▁systems ▁are ▁essentially ▁the ▁same ▁as ▁those ▁that ▁are ▁information - the oret ically ▁secure . ▁Nevertheless , ▁it ▁does ▁not ▁always ▁have ▁to ▁be ▁that ▁way . ▁One ▁day , ▁R SA ▁might ▁be ▁proved ▁secure , ▁as ▁it ▁re lies ▁on ▁the ▁assertion ▁that ▁factor ing ▁large ▁numbers ▁is ▁hard , ▁thus ▁becoming ▁un condition ally ▁secure , ▁but ▁it ▁will ▁never ▁be ▁information - the oret ically ▁secure ▁because ▁even ▁if ▁no ▁efficient ▁algorithms ▁for ▁factor ing ▁large ▁pr imes ▁exist , ▁it ▁could ▁still ▁be ▁done ▁in ▁principle ▁with ▁un limited ▁computational ▁power . ▁ ▁Phys ical ▁layer ▁encryption ▁ ▁A ▁we aker ▁notion ▁of ▁security , ▁defined ▁by ▁A aron ▁D . ▁W yn er , ▁established ▁a ▁now - fl our ishing