Cryptography Reference
In-Depth Information
elements in the set
n −
1. Kwan, for in-
stance, orders the RGB colors in the palette of the GIF by using what
he calls the “natural” order. That is, every color is assigned the value
2
16
× Red
+2
8
× Blue
+
Green
S
come ordered from 0 to
and then sorted accordingly.
Many of the sorting strategies used above can also be used to sort
the elements. If they are encrypted with a particular key before the
sorting then the key acts as a key for this steganography.
This algorithm can be particularly efficient in the right situations.
Imagine you have all 65,536 two byte values arranged in a list. This
takes 128
k
bytes. This list can store 119255bytes with this algorithm—
close to 90% of the payload. Of course, good steganographic oppor-
tunities like shopping lists are rarely so compact, but the theoretical
potential is still astonishing.
13.8 Word Scrambling
One commonly cited observation from cognitive science is that hu-
mans can read words even if the order of some of the internal letters
are reordered. Apparently the words are usually understandable if
the first and last letters are left unchanged. The mind seems to pay
particular attention to the first and last letter while ignoring the ab-
solute order of the interior letters.
Here's a sample:
At Pairs, jsut atfer dark one gusty eivnneg in the auutmn
of 18, I was einonyjg the tofolwd luxury of mittoiaedn
and a mehuseacrm, in cnpmaoy wtih my fnired C. Aug-
sute Diupn, in his lttile back lrraiby, or book-coelst, au
tiosrime, No. 33 Rue Donot, Fuuoarbg St. Giearmn. For
one hour at lesat we had maniienatd a pofunord sielcne;
wilhe ecah, to any caasul osvreebr, might hvae seemed in-
ntetly and eilesulcvxy oipcecud with the cilunrg eiddes of
sokme taht oppressed the apoestrhme of the ceahmbr. For
melsyf, heovewr, I was mletnlay dusiscisng cietarn tipocs
wichh had foermd mettar for ciestnovoarn bteeewn us at
an eielarr pioerd of the eiennvg; I mean the aiffar of the
Rue Mogure, and the mestryy aintentdg the meudrr of
Miare Rogt. I leookd on it, torfeerhe, as sioetnhmg of a
coniiccende, wehn the door of our apetnarmt was torwhn
open and aittedmd our old aincqatcanue, Mioesunr G, the
Pfeecrt of the Piasairn piolce.
He re's t he o r i g i na l f r om Edga r A l l an Poe 's
Purloined Letter
:
