Cryptography Reference
In-Depth Information
choices are often not hard to add. You could have 1024 names of
people that could be produced as the noun of the sentence. That
would encode 10 bits in one swoop. The only limitation is your
imagination.
Assessing the resistance to attack is more complicated. The hard-
est test can be fooling a human. The text produced in Chapter 6
may look correct statistically, but even the best fifth-order text seems
stupid to the average human. The grammatical text produced from
this process can be as convincing as someone can make the gram-
mar. The example that produced the text in Figure 7.1 shows how
complicated it can get. Spending several days on a grammar may
well be worth the effort.
There are still limitations to the form. Context-free grammars
have a fairly simple form. This means, however, that they don't keep
track of information particularly well. The example in Figure 7.1
shows how strikes, balls, and outs can be kept straight, but it fails
to keep track of the score or the movement of the base runners. A
substantially more complicated grammar might begin to do this, but
there will always be limitations to writing the text in this format.
“Language exerts
hidden power, like a
moon on the tides.”-
Rita Mae Brown,
Starting From Scratch
The nature of being
context-free
also imposes deeper problems on
the narrative. The voice-over from a baseball game is a great conceit
here because the story finds itself in the same situation over and over
again. The batter is facing the pitcher. The details about the score
and the count change, but the process repeats itself again and again
and again.
Creating a grammar that produces convincing results can either
be easy or hard. The difficulty depends, to a large extent, on your
level of cynicism. For instance, anyone could easily argue that the
process of government in Washington, D.C. is a three-step process:
1. Member of Congress X threatens to change regulation Y of in-
dustry Z.
2. Industry Z coughs up money to the re-election campaign of
other members P, D, and Q.
3. P, D, and Q stop X's plan in committee.
If you believe that life inWashington, D.C. boils down to this basic
economic process, you would have no problem coming up with a
long, complicated grammar that spins out news from Washington.
The same can be said for soap operas or other distilled essences of
life.
There are deeper questions about the types of mathematical at-
tacks that can be made on the grammars. Any attacker who wanted
