even illegal. This was, after all, the Congo, and things were different in the Congo.
Colonel Supo had issued vouchers for the services provided, and it was even possible that at some time in the future they would be honored by the Congolese government. The management was going to provide an essentially identical bill to the commanding officer, SFDET-17 in the field, with the understanding that it would be paid in U.S. dollars immediately.
The SFDET-17 bill differed from the bill rendered to Colonel Supo’s headquarters in that, in the SFDET-17 bill, the cost of beer, wine, and spirits served would be incorporated into the cost of the meals served, and the words “beer,” “wine,” and “spirits” would not appear thereon.
There were already some radio antennae on the roof of the Hotel du Lac when Spec7 Peters/Captain Weewili went up the first time to see where he could install his antennae, and he was fascinated with what he found, much as when a car aficionado discovers a Model T Ford in daily use.
His antennae, including two dishes, were state of the art, so much so that he was a little uneasy when Lieutenant/Mr. Portet asked for an explanation of how everything worked. Just about all of the equipment he’d brought with him was classified, and you were supposed to have a need-to-know. He finally decided that, in these circumstances, Portet had the need-to-know anything and everything.
“Most of the aviation stuff is pretty standard,” Peters explained. “But the commo is nonstandard, state of the art, and classified.”
“How does it work?”
“We don’t talk about it much,” Peters explained, “but we’re tied into the datalinks of the surveillance satellites. They have a reception capability—to turn the cameras on and off, you know, stuff like that—and we use that for our commo.
“First, we go through the usual encryption process, break it down into five character blocks. . . . You know how that works, I guess?”
Jack had nodded, although he really didn’t have a clue how that worked.
“After we get the encrypted message on tape, then we condense it,” Peters said.
“How does that work?”
“You put the encrypted tape on one machine, and a blank tape on a second machine. The first machine is running, say, 480 times as fast as the second machine. If, for example, you had 960 seconds of data, eight minutes’ worth, it gets copied onto two seconds’ worth of tape on the second machine. And most messages are a lot shorter than eight minutes, more like two, before condensation. When you condense a two-minute tape at 480—and we can go as high as 960 and even 1920, but sometimes the tape won’t take it that short—when you condense a two-minute tape at 480, you get a half-second uplink tape. You bury that in garbage—”
“What?”
“You send a long uplink tape . . . sometimes, depending on how long the satellite will be over you, an hour, and hour and a half. They call it garbage because the five-character blocks, which look like crypto, aren’t; they’re meaningless, randomly selected. I brought about twenty hours’ worth with me. So what you do is re-record say forty-five minutes of that, and you slip the half-second—sometimes shorter—crypto message in between a couple of characters in the garbage blocks. Still with me?”
“I don’t know,” Jack confessed.
“So we’ll send that up to the satellite,” Peters said. “The satellite records it, and then, when the satellite gets over Washington—actually, we have antennae farms at Vint Hill Farms Station in Virginia, and at Fort Meade, over in Maryland—the satellite downlinks it. Okay?”
“I’m beginning to be sorry I asked,” Jack confessed.
“Then they run the tape fast through one of their machines, until they hit the trigger—”
“What trigger?”
“The crypto message has an impulse—like a 300-cycle tone, you know? The exact frequency is in a Signal Operations Instruction, so maybe one day it’s 299 cps, and the next 1,202, and so on. Anyway, when the fast machine hits a trigger, it stops, backs up to the trigger, and then starts running at slow speed. That’s fed to a crypto machine, and that’s it. Out of the crypto machine comes the decrypted message.”
Jack thought it over for a long moment.
“So what the bad guys have to do is play the whole tape—the garbage tape—looking for the trigger. . . .”
“Right.”
“Which is hidden somewhere in a half-second encrypted message in tape maybe forty-five minutes long. . . .”
“Right.”
“And if they get lucky, then all they have to do is break the encryption code?”