programming-for-dummies

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Cracking Encryption
Hiding in plain sight with steganography
One unusual form of encryption involves hiding
data within another chunk of data, such as
hiding a text message inside an audio or
graphic image. Hiding data within another form
of data is steganography. The idea is that no
one can read your messages if he can’t find
them in the first place.
Steganography works on the principle that data
in audio, video, and graphic files can be
removed without noticeably affecting the quality
of the original file. After removing chunks of
information from such a file, which leaves gaps
in the original file, the next step is to insert the
plaintext or ciphertext into these open gaps.
If you insert plaintext into an audio, video, or
graphic file, anyone can read your message if
he knows how to find it. If you encrypt your
message and then insert the ciphertext into a
file, someone would need to know where to find
your message and then know the password to
decrypt that message. Steganography isn’t
necessarily a form of encryption so much as it’s
a way to keep anyone from knowing you’re
sending secret messages at all.
Brute force attack
Basically, a brute force attack tries every possible combination of ways a
message can be scrambled. Think of a combination lock that opens only if
you align the right number. If the combination lock offers 36 numbers, you
can use a brute force attack and exhaustively try all 36 numbers until you
find the one that opens the lock.
Now consider a more complicated combination lock that not only displays
36 numbers but forces you to choose three different numbers in the correct
order. You can still exhaustively try every possible number combination, but
the time needed to do this is likely more than most people are willing to
take, which effectively makes the lock secure.
That’s the same idea behind encryption. Every form of encryption can eventually
be cracked with a brute force attack, but the time needed to exhaustively
try every possibility takes too much time. It’s possible to crack even
the toughest encryption algorithm with a brute force attack, but you might
need a room full of million-dollar supercomputers running 24 hours a day for
the next million years to eventually crack the encryption. By making the
costs in resources and time too high, encryption algorithms are essentially
unbreakable through a brute force attack alone.
A variation of the brute force attack is the Chinese lottery. The idea is that if
you gave each person in China (with its billion+ population) a computer and
assigned each computer a different range of brute force attacks on the same
encrypted data, eventually one of them will crack the encryption and hence
“win” the lottery.