Using brute force is not very effective on 256 keys. But this doesn't exclude the possibility of a breakthrough that reduce enormously the search space. For exa

Using brute force is not very effective on 256 keys. But this doesn't exclude the possibility of a breakthrough that reduce enormously the search space. For example even for AES there is an attack faster than brute force by a factor of about four ! http://research.microsoft.com/en-us/projects/cryptanalysis/aesbc.pdf http://research.microsoft.com/en-us/projects/cryptanalysis/a...