her later with an answer. It’s a no-brainer, really, but here’s the rub: If we take it, I’m not inclined to keep her in the dark.”
“About The Campus?” Granger said. “I don’t—”
“Sorry,” Clark said. “Mary Pat and I go back a long way, and she’s risking a lot on this. I’m not going to play her. Look, you guys know her reputation; you know what Jack Ryan thinks of her. If that’s not bona fides enough, I don’t know what is.”
Hendley mulled this over for half a minute, then nodded. “Okay. Tread carefully, though. When would she need you?”
“Yesterday, I suspect,” Clark replied.
44
WHAT WE know for sure about the Emir and the URC is limited,” Jerry Rounds said, restarting the meeting.
“Let’s talk about what we’re pretty sure about.”
“Up until recently, the URC’s relied heavily on the Net for communication, but we can’t track them down to an ISP because it’s always something different, and we depend on NSA to pick it up from the encryption method, and even then we can’t always identify the ISP, but they know they skip from one country to another.”
Dominic picked up the thread. “Unless we’re missing a whole bunch of e-traffic—which is always possible—it’s a safe bet he’s having important stuff physically transmitted from one place to another, which means couriers. Maybe carrying CD-ROMs or some other portable media they can use on a laptop, or can hand to somebody else in their outfit who has a desktop machine that’s hooked into a phone or cable line. Or a Wi-Fi hot spot.”
“Hot spots ain’t very secure,” Brian suggested.
“Might not matter,” Chavez countered. “Wasn’t one of the ideas that they’re using onetime pads?”
“Yeah,” Rounds said.
“With those you can say just about anything you want. To anybody picking it up, it’d look like a whole bunch of random numbers or letters or words.”
“Which begs the question,” Jack said, “are the couriers carrying just messages, or onetime pads, too—if that’s what they’re using—”
Rounds interrupted. “Jack, bring everyone up to speed on this guy. ...”
“Shasif Hadi,” Jack replied. “He was on an e-mail distribution list we’ve had our eye on. His ISP account wasn’t as well insulated as the others. We’re trying to peel back his financials. Whether that’ll lead to anything but which grocery store he shops at, I don’t know.”
“About the couriers,” Chavez said. “Doesn’t the FBI look at frequent travelers on the airlines? Any way of sorting a pattern that way? Find some link between URC e-mail traffic and travel patterns.”
Dominic answered this. “You have any idea how many people regularly hop the Atlantic? Thousands, and the Bureau’s looking at all of them. It’ll take a long time to check out as many as a quarter of them. It’s like reading through a phone book eight hours a day. And for all we know, the bastard’s sending his CD-ROMs by FedEx or even regular mail. A mailbox is a great place to hide something.”
Jerry Rounds’s laptop chimed, and he checked the screen. He read for a full minute, then said, “This complicates things.”
“What?” Jack said.
“We got an info dump from the Tripoli embassy thing. Ding inadvertently pocketed a flash drive from one of the tangos. The drive had a bunch of JPEG files on it.”
“Pictures of the Emir’s bolt-hole?” Brian asked.
“Not so lucky. The bad guys are upping their game. They’re using steganography.”
“Come again?”
“Steganography. Stego, for short. It’s a method of encryption—essentially, hiding a message inside an image.”
“Like invisible ink.”
“More or less, but it’s even older than that. In ancient Greece they used to shave a portion of a servant’s head, tattoo a message on the skull, then wait for the hair to grow back and send him through enemy lines. Here we’re talking about digital pictures, but the concept is the same. See, a digital image is nothing more than a whole bunch of colored dots.”
“Pixels,” Chavez offered.
“Right. Each pixel is assigned a number—a red, blue, and green value, usually ranging from zero to two fifty-five, depending on the intensity. Each of these are, in turn, stored in eight bits, starting at one twenty-eight and jumping down to one, halving as they go, so one twenty-eight to sixty-four to thirty-two, and so on. A difference in one or two or even four in the RGB value is imperceptible to the human eye—”
“You’re losing me,” Brian said. “Bottom-line it.”
“You’re essentially hiding characters inside a digital photo by slightly altering its pixels.”
“How much information?”
“Say, a six forty by four eighty image . . . half a