Cryptonomicon

Randy has the source code--the original program--for the videoconferencing software. It is reasonably clever in its use of bandwidth. It looks at the stream of frames (individual still images) coming from the pinhole camera and notices that, although the total amount of data in those frames is rather large, the difference from one frame to the next is tiny. It would be altogether different if Frame 1 were a talking head and Frame 2, a fraction of a second later, were a postcard shot of a Hawaiian beach and Frame 3 a diagram of a printed circuit and Frame 4 a closeup of a dragonfly's head. But in fact, each frame is a talking head--the same person's head, with minor changes in position and expression. The software can save on precious bandwidth by mathematically subtracting each new frame from the previous one (since, to the computer, each image is just a long number) and then transmitting only the difference.

What it all means is that this software has a lot of built-in capabilities for comparing one image with another, and gauging the magnitude of the difference from one frame to the next. Randy doesn't have to write that stuff. He just has to familiarize himself with these already-existing routines, learn their names and how to use them, which takes about fifteen minutes of clicking around.

Then he writes a little program called Mugshot that will take a snap shot from the pinhole camera every five seconds or so, and compare it to the previous snapshot, and, if the difference is large enough, save it to a file. An encrypted file with a meaningless, random name. Mugshot opens no windows and produces no output of its own, so the only way you can tell it's running is by typing the UNIX command

ps

and hitting the return key. Then the system will spew out a long list of running processes, and Mugshot will show up somewhere in that list.

Just in case someone thinks of this, Randy gives the program a fake name: VirusScanner. He starts it running, then checks its directory and verifies that it has just saved an image file: one mug shot of Randy. As long as he sits fairly still, it won't save any more mug shots; the pattern of light that represents Randy's face striking the far wall of the camera obscura won't change very much.

In the technology world, no meeting is complete without a demo. Cantrell and Föhr have developed a prototype of the electronic cash system, just to demonstrate the user interface and the built-in security features. "A year from now, instead of going to the bank and talking to a human being, you will simply launch this piece of software from any where in the world," Cantrell says, "and communicate with the Crypt." He blushes as this word seeps through the translators and into the ears of the others. "Which is what we're calling the system that Tom Howard has been putting together."

Avi's on his feet, coolly managing the crisis. 'Mì fú,"he says, speaking directly to the Chinese guys, "is a better translation."

The Chinese guys look relieved, and a couple of them actually crack smiles when they hear Avi speaking Mandarin. Avi holds up a sheet of paper bearing the Chinese characters (13):

Painfully aware that he has just dodged a bullet, John Cantrell continues with a thick tongue. "We thought you might want to see the software in action. I'm going to demo it on the screen now, and during the lunch break you should feel free to come around and try it out yourselves."

Randy fires up the software. He's got his laptop plugged into a video jack on the underside of the table so that the sultan's lurking media geeks can project a duplicate of what Randy's seeing onto a large projection screen at the end of the room. It is running the front end to the cash demo, but his mug shot program is still running in the background. Randy slides the computer over to John, who runs through the demo (there should be a mug shot of John Cantrell stored on the hard disk now).