For one AES is built for three key sizes 128, 192 or 256 bits.
Currently, brute-forcing 128 bits is not even close to feasible.
Hypothetically, if an AES Key had 129 bits, it would take twice
as long to brute-force a 129 bit key than a 128 bit key. This
means larger keys of 192 bits and 256 bits would take much much
much longer to attack. It would take so incredibly long to
brute-force one of these keys that the sun would stop burning
before the key was realized. That's a big freaking number.
That's how many possibly keys there are. Assuming the key is
random, if you divide that by 2 then you have how many keys it
will take on average to brute-force AES-256 In a sense we do
have the really big cipher keys you are talking of. The whole
point of a symmetric key is to make it unfeasible to brute-
force. In the future, if attacking a 256bit key becomes possible
then keysizes will surely increase, but that is quite a ways
down the road. The reason RSA keys are much larger than AES keys
is because they are two compl