Cryptonomicon

piece of red pumice shaped vaguely like the continent of Africa. Waterhouse squats no more than twenty feet away, trying to figure out how he can make his presence known without being gunned down by a nervous white man.

He almost gets close enough to tap Rudy on the shoulder. Then he slips on a slimy rock. Rudy hears him, turns, and sees nothing except for a swatch of undergrowth being torn down by Waterhouse's falling body.

'Is that you, Lawrence?'

Waterhouse stands up cautiously, keeping his hands in plain sight. 'Very good! How did you know?'

'Don't be stupid. There aren't that many people who could have found us.'

They shake hands. Then they think better of it, and embrace. Rudy gives him a cigarette. The German sailors look on incredulously. There are some others: a Negro and an Indian, and a grizzled, dark man who looks like he wants to kill Waterhouse on the spot.

'You must be the famous Otto!' Waterhouse exclaims. But Otto does not seem eager to make new friends, or even acquaintances, at this juncture in his life, and turns away sourly. 'Where's Bischoff?' Waterhouse asks.

'Minding the submarine. It is risky, lurking in the shallows. How did you find us, Lawrence?' He answers his own question before Waterhouse can. 'By decrypting the long message, obviously.'

'Yes.'

'But how did you do that? Did I miss something? Is there a back door?'

'No. It wasn't easy. I broke one of your messages, a while back.'

'The FUNERAL one?'

'Yes!' Waterhouse laughs.

'I could have killed Enoch for sending out a message with such an obvious crib.' Rudy shrugs. 'It is hard to teach crypto security, even to intelligent men. Especiallyto them.'

'Maybe he wanted me to decrypt it,' Waterhouse muses.

'It is possible,' Rudy admits. 'Perhaps he wanted me to break Detachment 2702's one-time pad, so that I would come and join him.'

'I guess he figures if you're smart enough to break hard codes, you're automatically going to be on his side,' Waterhouse says.

'I'm not sure that I agree . . . it is naive.'

'It's a leap of faith,' Waterhouse says.

'How did you break Arethusa? I am naturally curious,' Rudy says.

'Because Azure/Pufferfish employs a different key every day, I assumed that Arethusa did the same.'

'I call them by different names. But yes, continue.'

'The difference is that the daily key for Azure/Pufferfish is simply the numerical date. Very easy to exploit, once you have figured it out.'

'Yes. I intended it that way,' Rudy says. He lights up another cigarette, taking extravagant pleasure in it.

'Whereas the daily key for Arethusa is something I haven't been able to put my finger on yet. Perhaps a pseudo-random function of the date, perhaps random numbers you are taking from a one-time pad. In any case it is not predictable, which makes Arethusa harder to break.'

'But you did break the long message. Would you explain how?'

'Well, your meeting at the cemetery was brief. I guess you had to get out of there pretty fast.'

'It did not seem a good place to linger.'

'So, you and Bischoff went away-back to the submarine, I figured. Goto Dengo went back to his post at The General's headquarters. I knew that he couldn't have told you anything substantive at the cemetery. That would have to come later, and it would have to be in the form of an Arethusa-encrypted message. You are justifiably proud of Arethusa.'

'Thank you,' Rudy says briskly.

'But the drawback of Arethusa, as with Azure/Puffeffish, is that it requires a great deal of computation. This is fine if you happen to have a computing machine, or a room full of trained abacus operators. I assume you have a machine on board the submarine?'

'That we do,' Rudy says diffidently, 'nothing very special. It still requires a great deal of manual calculation.'

'But Enoch Root in Manila, and Goto Dengo, could not have had such a thing. They would have to encrypt the message by hand-doing all of the calculations on sheets of scratch paper. Enoch already knew the algorithm,and could tell it to Goto Dengo, but you would have to agree on a keyto put into that algorithm. The only time you could have decided on the key was while you were all together at the cemetery. And during your conversation there, I saw you pointing at Shaftoe's headstone. So I figured that you were using that as a key-maybe his name, maybe his dates of birth and death, maybe his military serial number. It turned out to be the serial number.'

'But still you did not know the algorithm.'

'Yes, but I had some idea that it was related to the Azure/Pufferfish algorithm, which in turn is related to the zeta functions that we studied at Princeton. So I just sat down and said to myself if Rudy were going to build the ultimate cryptosystem on this basis, and if Azure/Pufferfish is a simplified version of that system, then what is Arethusa? That gave me a handful of possibilities.'

'And out of that handful you were able to pick the right one.'

'No,' Waterhouse says, 'it was too hard. So I went to the church where Enoch was working, and looked through his wastebasket. Nothing. I went to Goto Dengo's office and did the same. Nothing. Both of them were burning their scratch paper as they went along.'

Rudy's face suddenly relaxes. 'Oh, good. I was afraid they were doing something incredibly stupid.'

'Not at all. So, you know what I did?'

'What did you do, Lawrence?'

'I went and had an interview with Goto Dengo.'

'Yes. He told us that much.'

'I told him about the research I had been doing into Azure/Pufferfish, but I didn't tell him I had broken it. I got him talking, in a very general way, about what he was doing on Luzon during the last year. He told me the same story that he has stuck to all along, which is that he was building some minor fortifications somewhere, and that after escaping from that area he wandered lost in the jungle for several days before emerging near San Pablo and joining up with some Air Force troops who were heading north towards Manila.

' 'It's a good thing you got out of there,' I told him, 'because ever since then, the Hukbalahap leader who calls himself the Crocodile has been ransacking the jungle-he's convinced that you Nipponese buried a fortune in gold there.' '

As soon as the word 'crocodile' emerges from Waterhouse's mouth, Rudy's face screws up in disgust and he turns away.

'So when the long message was finally transmitted last week, from the transmitter that Enoch has hidden on the top of that church's bell tower, I had two cribs. First of all, I suspected that the key was a number from the tombstone of Bobby Shaftoe. Secondly, I was confident that the words 'Hukbalahap,' 'crocodile,' and probably 'gold' or 'treasure' would appear somewhere in the message. I also looked for obvious candidates like 'latitude' and 'longitude.' With all of that to go on, breaking the message wasn't that hard.'

Rudy von Hacklheber heaves a big sigh. 'So. You win,' he says. 'Where is the cavalry?'

'Cavalry, or calvary?' Waterhouse jokes.

Rudy smiles tolerantly. 'I know where Calvary is. Not far from Golgotha.'

'Why do you think the cavalry is coming?'

'I know they are coming,' Rudy says. 'Your efforts to break the long message must have required a whole room full of computers. They will talk. Surely the secret is out.' Rudy stubs out his half-smoked cigarette, as if preparing to leave. 'So, you have been sent to give us an offer-surrender in a civilized way and we will get good treatment. Something like that.'

'Au contraire, Rudy. No one knows except me. I did leave a sealed envelope in my desk, to be opened if I should die mysteriously on this little trip to the jungle. That Otto character has a fearsome reputation.'

'I don't believe you. It is impossible,' Rudy says.