Brute force attack.
This is the most common type of attack against ciphers.
The attacker uses trial and error technique to guess the encryption key.
Starting with names of pets, birthday and any other commonly used passwords.
If that doesn't work he will try any combinations of letters.
First of all a pure brute force attack against a 256 bits symmetric cipher
is not likely.
There are more combinations in a 256 bits key than there are atoms in
the galaxy.
Even if there are many collisions and repeating subkeys in the algorithm,
this is
not usually helpful in key sizes from 112 bits above. So guessing weak
cipher keys
is the most likely scenario.
To counter brute force attacks and Related-key attack, the
system uses
a key scheduling algorithm that uses around 10 sec on a pentium 4, 3Ghz
PC.
This is a very long time, but since we are just talking about encryption
of text.
The user can live with the delay. Even trying a small amount of cipher
keys
will take a very long time, even with a super computer.
Still choosing a strong key is vital, try blending any characters like
#8@%]¤.
You can also type inn characters not present at the keyboard like ±.
This can be done by holding the left alt key down ant typing in the
ASCII decimal code for that character (241 in this case). Read
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