Cryptonomicon (118 page)

SEND HELP IMMEDIATELY

and

XUEBP TOAFF NMQPT

they have no inherent ability to recognize the first as a successful decryption of a message and the second as a failure. But they can do a frequency count on the letters. If the computer finds that E is the most common, followed by T, and so on and so forth, then it’s a pretty strong indication that the text is some natural human language and not just random gibberish. By using this and other slightly more sophisticated tests, Randy’s come up with a routine that should be pretty good at recognizing success. And it’s telling him this morning that 4 April 1945 is broken. Randy dare not display the decrypted messages onscreen for fear that they contain the information that Wing’s looking for, and so he cannot actually read these messages, as desperately as he’d like to. But by using a command called
grep,
which searches through text files without opening them, he can at least verify that the word
MANILA
occurs in two places.

Based on this break, with several more days’ work Randy solves Arethusa entirely. He comes up, in other words, with
A(x)
=
K,
such that for any given date
x
he can figure out what
K,
the keystream for that day would be; and just to prove it, he has the computer crank out
K
for every day in 1944 and 1945 and then use them to decrypt the Arethusa intercepts that came in on those days (without displaying them) and does the frequency count on them and verifies that it worked in each case.

So now he has decrypted all of the messages. But he cannot actually read them without transmitting their contents to Wing. And so now, the subliminal channel comes into play.

In cryptospeak, a subliminal channel is a trick whereby secret information is subtly embedded in a stream of other stuff. Usually it means something like manipulating the least significant bits of an image file to convey a text message. Randy’s drawn inspiration from the concept in his labors here in jail. Yes, he has been working on decrypting Arethusa, and that has involved screwing around with a tremendous number of files and writing a lot of code. The number of separate files he’s read, created, and edited in the last few weeks is probably in the thousands. None of them have had title bars on their windows, and so the Van Eck
phreakers surveilling him have presumably had a terrible time keeping track of which is which. Randy can open a file by typing its title in a window and hitting the return key, all of which happens so fast that the surveillance people probably don’t have time to read or understand what he has typed before it disappears. This, he thinks, may have given him just a bit of leeway. He has kept a subliminal channel going in the background: working on a few other bits of code that have nothing to do with breaking Arethusa.

He got the idea for one of these when he was paging through the
Cryptonomicon
and discovered an appendix that contained a listing of the Morse code. Randy knew Morse code when he was a Boy Scout, and learned it again a few years ago when he was studying for a ham radio license, and it doesn’t take him long to refresh his memory. And neither does it take him very long to write a little bit of code that turns his computer’s space bar into a Morse code key, so that he can talk to the machine by whacking out dots and dashes with his thumb. This might look a little conspicuous, if not for the fact that Randy spends half of his time reading text files in little windows on the screen, and the way you page through a text file in most UNIX systems is by whacking the space bar. All he has to do is whack it in a particular rhythm, a detail he’s relying on the surveillance guys to miss. The results all go into a buffer that is never displayed on the screen, and get written out to files with completely meaningless names. So, for example, Randy can whack out the following rhythm on his spacebar while pretending to read a lengthy section of the
Cryptonomicon
:

dash dot dot dot (pause) dot dot dash (pause) dash dot (pause) dash dot dot (pause) dash dash dash (pause) dash dot dash

which ought to spell out
BUNDOK
. He doesn’t want to open the resulting file on screen, but later, while he’s in the middle of a long series of other cryptic commands he can type

grep ndo (meaningless file name) > (another meaningless file name)

and grep will search through the first-named file to see if it contains the string “ndo” and put the results into the second-named file, which he can then check quite a bit later. He can also do “grep bun” and “grep dok” and if the results of all of these greps are true then he can be pretty confident that he has successfully coded the sequence “
BUNDOK
” into that one file. In the same way he can code “
COORDINATES
” into some other file and “
LATITUDE
” into another, and various numbers into others, and finally by using another command called “cat” he can slowly combine these one-word files into longer ones. All of these demands the same ridiculous patience as, say, tunneling out of a prison with a teaspoon, or sawing through iron bars with a nail file. But there comes a point, after he’s spent about a month in jail, when suddenly he’s able to make a window appear on the screen that contains the following message:

COORDINATES OF PRIMARY STORAGE LOCATIONS

SITE BUNDOK: LATITUDE NORTH FOURTEEN DEGREES THIRTY-TWO MINUTES… LONGITUDE EAST ONE TWO ZERO DEGREES FIFTY-SIX MINUTES…

SITE MAKATI: (etc.)

SITE ELDORADO: (etc.)

All of which is total bullshit that he just made up. The coordinates given for the Makati site are those of a luxury hotel in Manila, sited at a major intersection that used to be the site of a Nipponese military airbase. Randy happens to have these numbers in his computer because he took them down during his very early days in Manila, when he was doing the GPS survey work for siting Epiphyte’s antennas. The coordinates given for
SITE ELDORADO
are simply the location of the pile of gold bars that he and Doug Shaftoe went to examine, plus a small random error factor. And those given for
SITE BUNDOK
are the real coordinates of Golgotha plus a couple of random error factors that should have Wing digging a deep hole in the ground about twenty kilometers away from the real site.

How does Randy know that there is a site called Golgotha, and how does he know its real coordinates? His computer told him using Morse code. Computer keyboards have LEDs on them that are essentially kind of useless: one to tell you when NUM LOCK is on, one for CAPS LOCK, and a third one whose purpose Randy can’t even remember. And for no reason other than the general belief that every aspect of a computer should be under the control of hackers, someone, somewhere, wrote some library routines called XLEDS that make it possible for programmers to turn these things on and off at will. And for a month, Randy’s been writing a little program that makes use of these routines to output the contents of a text file in Morse code, by flashing one of those LEDs. And while all kinds of useless crap has been scrolling across the screen of his computer as camouflage, Randy’s been hunched over gazing into the subliminal channel of that blinking LED, reading the contents of the decrypted Arethusa intercepts. One of which says:

THE PRIMARY IS CODE NAMED GOLGOTHA. COORDINATES OF THE MAIN DRIFT ARE AS FOLLOWS: LATITUDE NORTH
(etc.)

A
T THIS POINT IN HISTORY
(A
PRIL OF 1945) THE
word that denotes a person who sits and performs arithmetical calculations is “computer.” Waterhouse has just found a whole room full of dead computers. Anyone in his right mind—anyone other than Waterhouse and some of his odd Bletchley Park friends, like Turing—would have taken one look at these computers and assumed that they were the accounting department, or something, and that each slave in the room was independently toting up figures. Waterhouse really
ought
to remain open to this idea, because it is so obvious. But from the very beginning he has had a hypothesis of his own, much more interesting and peculiar. It is that the slaves were functioning, collectively, as cogs in a
larger computation machine, each performing a small portion of a complex calculation: receiving numbers from one computer, doing some arithmetic, producing new numbers, passing them on to another computer.

Central Bureau is able to trace the identities of five of the dead slaves. They came from places like Saigon, Singapore, Manila, and Java, but they had in common that they were ethnic Chinese and they were shopkeepers. Apparently the Nipponese had cast a wide net for expert abacus users and brought them together, from all over the Co-Prosperity Sphere, to this island in Manila Bay.

Lawrence Waterhouse tracks down a computer of his own in the ruins of Manila, a Mr. Gu, whose small import/export business was destroyed by the war (it is hard to run such a business when you are on an island, and every ship that leaves or approaches the island gets sunk by Americans). Waterhouse shows Mr. Gu photos of the abaci as they were left by the dead computers. Mr. Gu tells him what numbers are encoded in those bead positions, as well as giving Waterhouse a couple of days’ tutorial on basic abacus technique. The important thing learned from this is not really abacus skills but rather the remarkable speed and precision with which a computer like Mr. Gu can churn out calculations.

At this point, Waterhouse has reduced the problem to pure data. About half of it’s in his memory and the other half scattered around on his desk. The data includes all of the scratch paper left behind by the computers. To match up the numbers on the scratch paper with the numbers left on the abaci, and thus to compile a flash-frozen image of the calculations that were underway in that room when the apocalypse struck, is not that difficult—at least, by the standards of difficulty that apply during wartime, when, for example, landing several thousand men and tons of equipment on a remote island and taking it from heavily armed, suicidal Japanese troops with the loss of only a few dozen lives is considered to be easy.

From this it is possible (though it approaches being difficult) to generalize, and to figure out the underlying mathematical algorithm that generated the numbers on the abaci.
Waterhouse becomes familiar with some of the computers’ handwriting, and develops evidence that slips of scratch paper were being handed from one computer to another and then to yet another. Some of the computers had logarithm tables at their stations, which is a really important clue as to what they were doing. In this way he is able to draw up a map of the room, with each computer’s station identified by number, and a web of arrows interconnecting the stations, depicting the flow of paper, and of data. This helps him visualize the collective calculation as a whole, and to reconstruct what was going on in that subterranean chamber.

For weeks it comes in bits and pieces, and then one evening, some switch turns on in Lawrence Waterhouse’s mind, and he knows, in some preconscious way, that he’s about to get it. He works for twenty-four hours. By that point he has come up with a lot of evidence to support, and none to contradict, the hypothesis that this calculation is a variant of a zeta function. He naps for six hours, gets up, and works for another thirty. By that point he’s figured out that it definitely is some kind of zeta function, and he’s managed to figure out several of its constants and terms. He almost has it now. He sleeps for twelve hours, gets up and walks around Manila to clear his head, goes back to work, and hammers away at it for thirty-six hours. This is the fun part, when big slabs of the puzzle, painstakingly assembled from fragments, suddenly begin to lock together, and the whole thing begins to make sense.

It all comes down to an equation written down on one sheet of paper. Just looking at it makes him feel weirdly nostalgic, because it’s the same type of equation he used to work with back at Princeton with Alan and Rudy.

Another pause for sleep, then, because he has to be alert to do the final thing.

The final thing is as follows: he goes into the basement of a building in Manila. The building has been turned into a signals intelligence headquarters by the United States Army. He is one of some half-dozen people on the face of the planet who are allowed to enter this particular room. The room amounts to a bit more than a quarter of the
basement’s total square footage, and in fact shares the basement with several other rooms, some of which are larger than it is, and some of which are serving as offices for men with higher rank than Waterhouse wears on his uniform. But there are a few oddities connected with Waterhouse’s room:

(1) At any given moment, no fewer than three United States Marines are loitering directly in front of the door of this room, carrying pump shotguns and other weapons optimized for close-range indoor flesh-shredding.

(2) Lots of power cables go into this room; it has its own fuse-panel, separate from the rest of the building’s electrical system.

(3) The room emits muffled, yet deafening quasimusical noises.

(4) The room is referred to as the Basement, even though it’s only part of the basement. When “the Basement” is written down, it is capitalized. When someone (let’s say Lieutenant Colonel Earl Comstock) is going to verbalize this, he will come to a complete stop in mid-sentence, so that all of the preceding words kind of pile into each other like cars in a colliding train. He will, in fact, bracket “the Basement” between a pair of full one-second-long caesuras. During the first of these, he will raise his eyebrows and purse his lips simultaneously, altering the entire aspect ratio of his face so that it becomes strikingly elongated in the vertical dimension, and his eyes will dart sideways in case any Nipponese spies somehow managed to escape the recent apocalypse and found a place to lurk around the fringes of his peripheral vision. Then he will say “the” and then he will say “Basement,” drawing out the
s
and primly articulating the
t
. And then will come another caesura during which he will incline his head towards the listener and fix him with a sober, appraising look, seeming to demand some kind of verbal or gestural acknowledgment from the listener that something appallingly significant has just passed between them. And then he will continue with whatever he was saying.

Waterhouse nods to the Marines, one of whom hauls the door open for him. A really funny thing happened shortly after the Basement was established, when it was still just a
bunch of wooden crates and a stack of 32-foot-long sewer pipe segments, and the electricians were still running in the power lines: Lieutenant Colonel Earl Comstock tried to enter the Basement to inspect it. But owing to a clerical error, Lieutenant Colonel Earl Comstock’s name was not on the list, and so a difference of opinion ensued that culminated with one of the Marines drawing his Colt .45 and taking the safety off and chambering a round, pressing the barrel of the weapon directly into the center of Comstock’s right thigh, and then reminiscing about some of the spectacular femur-bursting wounds he had personally witnessed on places like Tarawa and in general trying to help Comstock visualize just what his life would be like, both short- and long-term, if a large piece of lead were to pass through the middle of said major bone. To everyone’s surprise, Comstock was delighted with this encounter, almost enchanted, and hasn’t stopped talking about it since. Of course, now his name’s on the list.

The Basement is filled with ETC card machines and with several racks of equipment devoid of corporate logos, inasmuch as they were designed and largely built by Lawrence Pritchard Waterhouse in Brisbane. When all of these things are hooked together in just the right way, they constitute a Digital Computer. Like a pipe organ, a Digital Computer is not so much a machine as a meta-machine that can be made into any of a number of different machines by changing its internal configuration. At the moment, Lawrence Pritchard Waterhouse is the only guy in the world who understands the Digital Computer well enough to actually do this, though he’s training a couple of Comstock’s ETC men to do it themselves. On the day in question, he is turning the Digital Computer into a machine for calculating the zeta function that he thinks is at the core of the cryptosystem called Azure or Pufferfish.

The function requires a number of inputs. One of these is a date. Azure is a system for generating one-time pads that change every day, and circumstantial evidence from the room of the dead abacus slaves tells him that, at the moment of their death, they were working on the one-time pad for 6 August 1945, which is four months in the future.
Waterhouse writes it down in the European style (day of the month first, then month) as 06081945, then lops off the leading zero to get 6,081,945—a pure quantity, an integer, unmarred by decimal point, rounding error, or any of the other compromises so abhorrent to number theorists. He uses this as one of the inputs to the zeta function. The zeta function requires a few other inputs too, which the person who designed this cryptosystem (presumably Rudy) was at liberty to choose. Surmising which inputs Rudy used has occupied much of Waterhouse’s thoughts in the last week. He puts in the numbers he has guessed, anyway, which is a matter of converting them to binary notation and then physically incarnating those ones and zeros on a neat row of stainless-steel toggle switches: down for zero, up for one.

Finally he puts on his artilleryman’s ear protectors and lets the Digital Computer howl through the calculation. The room gets much hotter. A vacuum tube burns out, and then another one. Waterhouse replaces them. That’s easy because Lieutenant Colonel Comstock has made a basically infinite supply of tubes available to him—quite a remarkable feat during wartime. The filaments of all those massed tubes glow redly and shine palpable radiant heat across the room. The smell of hot oil rises from the louvers on the ETC card machines. The stack of blank cards in the input hopper shortens mysteriously as they vanish into the machine. Cards skitter into the output bin. Waterhouse pulls them out and looks at them. His heart is pounding very hard.

It’s quiet again. The cards have numbers on them, nothing more. They just happen to be exactly the same numbers that were frozen on certain abaci down in the room of the computer slaves.

Lawrence Pritchard Waterhouse has just demolished another enemy cryptosystem: Azure/Pufferfish may now be mounted like a stuffed head on the wall of the Basement. And indeed, looking at those numbers he feels the same kind of letdown that a big game hunter must feel when he’s stalked some legendary beast halfway across Africa and finally brought it down with a slug through the heart, walked up to the corpse, and discovered that after all it’s just a big,
messy, pile of meat. It’s dirty and it’s got flies on it. Is that all there is to it? Why didn’t he solve this thing a long time ago? All of the old Azure/Pufferfish intercepts can be decrypted now. He’ll have to read them, and they will turn out to be the usual numb mutterings of giant bureaucracies trying to take over the world. He doesn’t, frankly, care anymore. He just wants to get the hell out of here and get married, play the organ, and program his Digital Computer, and hopefully get someone to pay him a salary to do one or the other. But Mary’s in Brisbane and the war’s not over yet—we haven’t even gotten around to invading Nippon, for crissakes, and conquering the place is going to take
forever,
with all those plucky Nipponese women and children drilling on soccer fields with pointed bamboo staves—and it’s probably going to be something like 1955 before he can even get discharged from the military. The war is not over yet, and as long as it goes on they will need him to stay down here in the Basement doing more of what he just did.

Arethusa. He still hasn’t broken Arethusa. Now
that’s
a cryptosystem!

He’s too tired. He can’t break Arethusa just now.

What he really needs is someone to talk to. Not about anything in particular. Just to talk. But there’s only half a dozen people on the planet he can really talk to, and none of them is in the Philippines. Fortunately, there are long copper wires running underneath the oceans which made geographical location irrelevant, as long as you have the right clearance. Waterhouse does. He gets up and leaves the Basement and goes to have a chat with his friend Alan.