Cryptonomicon

He pours the milk with one hand while jamming the spoon in with the other, not wanting to waste a single moment of the magical, golden time when cold milk and Cap'n Crunch are together but have not yet begun to pollute each other's essential natures: two Platonic ideals separated by a boundary a molecule wide. Where the flume of milk splashes over the spoon-handle, the polished stainless steel fogs with condensation. Randy of course uses whole milk, because otherwise why bother? Anything less is indistinguishable from water, and besides he thinks that the fat in whole milk acts as some kind of a buffer that retards the dissolution-into-slime process. The giant spoon goes into his mouth before the milk in the bowl has even had time to seek its own level. A few drips come off the bottom and are caught by his freshly washed goatee (still trying to find the right balance between beardedness and vulnerability, Randy has allowed one of these to grow). Randy sets the milk-pod down, grabs a fluffy napkin, lifts it to his chin, and uses a pinching motion to sort of lift the drops of milk from his whiskers rather than smashing and smearing them down into the beard. Meanwhile all his concentration is fixed on the interior of his mouth, which naturally he cannot see, but which he can imagine in three dimensions as if zooming through it in a virtual reality display. Here is where a novice would lose his cool and simply chomp down. A few of the nuggets would explode between his molars, but then his jaw would snap shut and drive all of the unshattered nuggets straight up into his palate where their armor of razor-sharp dextrose crystals would inflict massive collateral damage, turning the rest of the meal into a sort of pain-hazed death march and rendering him Novocain mute for three days. But Randy has, over time, worked out a really fiendish Cap'n Crunch eating strategy that revolves around playing the nuggets' most deadly features against each other. The nuggets themselves are pillow-shaped and vaguely striated to echo piratical treasure chests.

Now, with a flake-type of cereal, Randy's strategy would never work. But then, Cap'n Crunch in a flake form would be suicidal madness; it would last about as long, when immersed in milk, as snowflakes sifting down into a deep fryer. No, the cereal engineers at General Mills had to find a shape that would minimize surface area, and, as some sort of compromise between the sphere that is dictated by Euclidean geometry and whatever sunken-treasure-related shapes that the cereal-aestheticians were probably clamoring for, they came up with this hard-to-pin-down striated pillow formation. The important thing, for Randy's purposes, is that the individual pieces of Cap'n Crunch are, to a very rough approximation, shaped kind of like molars. The strategy, then, is to make the Cap'n Crunch chew itself by grinding the nuggets together in the center of the oral cavity, like stones in a lapidary tumbler. Like advanced ballroom dancing, verbal explanations (or for that matter watching videotapes) only goes so far and then your body just has to learn the moves.

By the time he has eaten a satisfactory amount of Cap'n Crunch (about a third of a 25-ounce box) and reached the bottom of his beer bottle, Randy has convinced himself that this whole dance thing is a practical joke. When he reaches the hotel, Amy and Doug Shaftoe will be waiting for him with mischievous smiles. They will tell him they were just teasing and then take him into the bar to talk him down.

Randy puts on the last few bits of his suit. Any delaying tactics are acceptable at this point, so he checks his e-mail.

To: randy@epiphyte.com

From: root@eruditorum.org

Subject: The Pontifex Transform, as requested

Randy,

You are right, of course--as the Germans learned the hard way, no new cryptosystem can be trusted until it has been published, so that people like your Secret Admirer friends can have a go at breaking it. I would be in your debt if you would do this with Pontifex.

The transform at the heart of Pontifex has various asymmetries and special cases that make it difficult to express in a few clean, elegant lines of math. It almost has to be written down as pseudo-code. But why settle for pseudo when you can have the real thing? What follows is Pontifex written as a Perl script. The variable $D contains the 54-element permutation. The subroutine e generates the next keystream value whilst evolving $D.

#!/usr/bin/perl -s

$f=$d?-1:1;$D=pack('C*'.33..86);$p=shift;

$p=~y/a-z/A-Z/;$U='$D=~s/(.*)U$/U$1/;

$D=~s/U(.)/$1U/;';($V=$U)=~s/U/V/g;

$p=~s/[A-Z]/$k=ord($&)-64,&e/eg;$k=0;

while(<>){y/a-z/A-Z/;y/A-Z//dc;$o.=$_}$o.='X'

while length ($o)%5&&!$d;

$o=~s/./chr(($f*&e+ord($&)-l3)%26+65)/eg;

$o=~s/X*$// if $d;$o=~s/.{5}/$& /g;

print"$o\n";sub v{$v=ord(substr($D,$_[0]))-32;

$v>53?53:$v}

sub w{$D=~s/(.{$_[0]})(.*)(.)/$2$1$3/}

sub e{eval"$U$V$V";$D=~s/(.*)([UV].*[UV])(.*)/$3$2$l/;

&w(&v(53));$k?(&w($k)):($c=&v(&v(0)),$c>52?&e:$c)}