the cork a little early,” Biery said, “but I think we’ve hit the mother lode. That’s the good news. The bad news is it looks like they’re using three different encryption methods, so it’s going to take some time.”
“You have our attention,” Clark replied.
“First thing: The banner image we saw on the URC website showing Dirar’s murder—I think it’s a digital onetime pad. Essentially a decoding grid for plain-speak messages. Whether it’s outdated or current I don’t know yet.”
This was no surprise to Jack. What was old is new again, he knew. The OTP system was ancient—how ancient was a topic of debate among cryptography scholars, but its birth into the modern age was in 1917 with an AT&T engineer named Gilbert Vernam—and while there were a variety of OTP flavors, at its core it is a substitution cipher, most simply arranged in the form of a random alphanumeric grid: combing a character from the left-hand margin with a character from the top margin, and where they intersect in the grid’s body is the single character substitution. Encoding and decoding was time-consuming, but providing the OTP was restricted to only the sender and the receiver; it was virtually unbreakable. In this case, certain URC members would know to check certain websites on certain days and download certain images, which would then be steganographically decrypted, revealing a onetime pad with which plain-speak phone calls, letters, and e-mails could be securely transmitted.
The question was, Jack thought, how often did the URC rotate its online OTP? The only way to find that out was to try to match known URC messages with onetime-pad images in the same time frame.
“This could explain why the baby announcement e-mail has dead-ended,” Jack said. “They switched pads and we’ve been a step behind.”
Clark nodded and said, “Go ahead, Gavin.”
“Second: One of the larger image files on Nayoan’s DVD—didn’t have a match on any we pulled off URC sites. The algorithm’s still chewing on it, but based on what I’m seeing so far, we’ve got a whole lot of credit card and bank routing numbers.”
“Nayoan’s a URC treasurer,” said Chavez. “Sure as shit.”
“You’re checking the numbers?” Clark asked Gavin.
“Not yet. Which do you want first?”
“Credit cards. Easier to get and easier to dump than a bank account. Start with stuff in San Francisco and West Coast accounts. Might as well make hay while we’re out here.”
65
IF THEIR ENTRY into the Medina caused any curiosity it was well disguised, the Caruso brothers decided. It was not yet dark, of course, so there were plenty of obviously white and Western tourists still milling around vendors’ stalls and wandering through the switchback narrow alleyways; their presence was of little consequence. The sun was dropping below the horizon, however, and with the dimming light the Medina would slowly empty of outsiders, leaving behind only locals and those few-and-far-between tourists who were either familiar enough with Tripoli or ignorant of its hazards. There were few murders of tourists in the Medina, Archie had assured them, but nocturnal muggings and purse snatchings were almost considered a sport here. Thieves had a discerning eye for the unmindful and the weak. Brian and Dom would appear neither, Archie had observed, so they had little to worry about. The Aussie’s brown-bag present in the trunk—a pair of Browning 9-millimeter Hi-Power Mark III semiautomatics, sans serial numbers, and four magazines of low-velocity hollow-points—made doubly sure of this. The noise suppressors Andy had provided were bench-made from PVC piping, each about the size of two soda cans stacked atop each other and spray-painted black. Neither would last more than a hundred rounds before losing its effectiveness, but since they had only forty rounds between them, the point was moot.
For twenty minutes they wandered through the stucco- and brick-walled alleys, stopping at portable vendor stalls and shops to look at the merchandise, all the while following Archie’s map, which Brian folded in his hand. Archie had given them several routes to Rafiq Bari’s apartment, and several routes out, including two E&E—escape and evasion—paths, an addition that had solidified their hunch that their contact was ex-military, probably Australian SASR, or Special Air Service Regiment. It was an insight of no small comfort: The Aussie’s mind-set was aligned with their own.
“Something smells good,” Dom said, sniffing.
The air was full of scents: burning charcoal, broiled meat, spices, as well as the stink of a thousand sweating bodies packed into enclosed spaces. The noise, too, was at first disorienting, a cacophony of Arabic, French,