“What are you talking about? The hard drive’s been erased.”
“Yes. But that doesn’t mean the data’s gone.”
He shook his head. “I don’t understand.”
“It’s like this. When you erase data on a hard drive, you’re really just overwriting that data with random zeros and ones. But you see, when the read/write head writes that new data, it uses only enough signal necessary to set the bit. That’s the way hard drives work: just enough signal, and no more.”
“Why is that?”
“To make sure that adjoining bits aren’t affected. Anyway, because the signal isn’t powerful enough to fully saturate the platter, whatever data was previously there is—like a ghost—going to affect the overall strength of the signal in that location.”
Crane looked at her, uncomprehending.
“Let’s say you have two positions on a hard drive, side by side. The first contains a zero, the second contains a one. Then somebody comes along and overwrites those two positions with two ones. So now we have a one in both positions. But guess what? Because the read/write head uses the bare minimum of signal to write those ones, the position that had a zero in it before has a weaker signal strength than the position that had a one in it.”
“So the data that was there before affects the new data that overwrites it,” Crane said.
“Exactly.”
“And you’ve got a tool that can resurrect that old, overwritten data?”
Hui nodded. “It takes an absolute value of the signal and subtracts it from what’s actually on the hard disk. That leaves us with a shadow image of what had been there before.”
“I had no idea that was possible.” Crane paused. “But wait a minute. The data wasn’t overwritten. You said it was degaussed. Demagnetized. How can you restore that?”
“Whatever kind of degausser was used, it doesn’t seem to have been very powerful: probably a hand-held model. Or maybe the person who did this didn’t take into account that the platters of the hard disk have a small amount of shielding. Anyway, a light degaussing is the equivalent of overwriting the hard disk two, maybe three times. And my equipment has the capability of restoring data that’s been overwritten twice as many times as that.”
Crane could only shake his head.
“But the process is destructive. We’ll only have one pass at it—and that means we’ll need another hard drive to dump the reconstructed data onto. I trashed mine when I removed the PCB.” She glanced at him. “Can I borrow yours?”
Crane smiled. “Seems we’re going through laptops pretty fast. Sure, I’ll get it now.”
“I’ll get the data recovery started.” Hui pushed the magnifying glass aside and reached for her tool kit.
“You be safe.” And Crane turned and quietly left the lab.
41
The man calling himself Wallace limped quietly through the maze of passages making up the science facilities of the refitted Storm King oil platform. He moved more quickly than usual: he had only now received a message in his quarters—a coded signal, transmitted via low-frequency radio—and he had to pass it on to the operative on Deep Storm immediately.
The Tub left in twenty minutes, bound for the ocean floor. If he hurried, he might just make it.
Reaching his office, he turned on the light, then shut and locked the door. The courier bag sat on his desk, ready to be delivered to the Recovery Chamber on the lowest level of the platform. He opened it, rummaged through its contents, then pulled out a CD hand-labeled RADIOGRAPHS 001136–001152.
Image files—precisely what he needed.
He inserted the CD into his computer, loaded one of the images at random into memory. He removed the CD, placed it back in its jewel case, and returned it to the courier bag. Next, he wrote a short routine that would embed a message into the least significant bits of the pixels of the radiograph image. It was the work of five minutes to type in the computer program and double-check it for bugs.
The man pressed a function key, causing the short routine to execute. A question mark appeared on screen: the routine was requesting input. He carefully typed in the message he’d been ordered to relay. Then he paused, finger hovering over the enter key, while he examined the message for accuracy:
IF WORK IS NOT STOPPED
DESTROY FACILITY WITHIN 24 HOURS
Satisfied, he pressed the key. The message disappeared from the screen; there was a brief pause as the program converted the message into its binary equivalent, then hid it within the digital code of the radiograph. A short chirp indicated that the process had been completed successfully.
Wallace smiled.
Opening a drawer, he pulled out a writable CD, slid it into the drive, and instructed the computer to burn a copy of the doctored radiograph. While the machine worked, he sat back in his chair, cleaning his glasses with his shirttail. The image was not large, and within a few minutes the new disk had been burned. He ejected it and quickly powered down the computer, instantly destroying all traces of his work. Pulling a fresh jewel case from the open drawer, he inserted the CD, wrote the recipient’s name on it with a black marker, then slipped it into the courier bag.
He stood up, slung the bag over his shoulder, glanced at his watch.
Twelve minutes to spare. Excellent.
Unlocking his door, he stepped out, whistling to himself as he made his way to the Recovery Chamber and the waiting Tub.
42
Hui Ping sat bolt upright on the lab stool, dropping a screwdriver on the table with a clatter, as Crane crept into the lab.
“God!” she said. “You practically scared me to death.”
“Sorry.”
“You took so long. What happened?”
“I just had to return a few messages, back in my stateroom.” Crane didn’t bother to mention the ten-minute questioning he’d just endured on his way back through the Barrier: two marines who were very eager to discover the location of Dr. Ping. There was no point making her more nervous than she already was.
“How are you coming?” he asked, stepping forward and placing his laptop on the table.
Hui was laboring over a complex contraption that, to Crane’s untrained eye, appeared to be several lab instruments joined by a forest of ribbon cables. In response to his question, she pushed herself away from the table.
“Just finished the last test.”
“Looks like rocket science to me.”
“It is rocket science. Almost. A magnetometer, chained to an A/D converter, and both in turn slaved to a timecode striper. The whole thing’s capable of making a bit-by-bit copy of Dr. Asher’s erased hard drive.”
Crane whistled. “Trust Asher to fit his labs up properly. What if you didn’t have all these cool toys?”
“The magnetometer is vital. I could do without the rest, but it would take a lot longer.” She reached for his laptop, then paused. “I’m going to have to wipe your hard drive. Sure you don’t mind?”
Crane shrugged. “Go ahead. All my files are on the network, anyway.”
Hui booted up his laptop and typed in a series of commands. “This may take a few minutes.”
A silence settled over the lab while the hard drive trundled.
“While retrieving my laptop, I did some thinking,” Crane said at last. “Whoever degaussed Asher’s computer wanted to make ultra sure what Asher discovered remained a secret.”
“I was thinking the same thing. But that person also didn’t want anybody to know he was trashing it.”
“Precisely my point. Otherwise they could have simply taken a sledgehammer to the laptop.”
“But who? And why?”
“The saboteur?” Crane said.
“Seems unlikely, doesn’t it? I don’t know his motives, but if I was the saboteur, I’d want that data for myself.” Hui stood up.
“My money’s on Korolis,” Crane said.
“Why’s that?”
“As far as I can tell, he lied about your presence at Outer Hul
l Receiving and in the hyperbaric suite.” He hesitated. “Does your resumé mention that internship at the data recovery facility?”
Hui nodded.
“So he knows about that, too. I don’t think he wants anybody learning what’s on this laptop.”
“I hope you’re wrong. He’d make a very dangerous enemy.” Hui stood up. “We’re set.”
Removing the case from his laptop, she attached the end of a ribbon cable to the hard drive, leaving the power cables connected. Then she powered up the chain of devices, made a few adjustments, and simultaneously engaged switches on the magnetometer and the digital timecode device. A low whirring filled the lab.
“How long will this take?” Crane asked.
“Not long. Apparently, Dr. Asher was like you—he did most of his work via dumb terminal on the Facility’s mainframe. I doubt the laptop holds more than his personal e-mail, Internet files, and the work on the codes.”
Ten minutes went by in which little was said. Hui monitored the extraction process while Crane puttered around the lab, picking up instruments and replacing them, trying not to grow impatient. At last the whirring noise stopped.
“That’s it.” Hui turned off the devices, removed the ribbon cable, placed the case back on Crane’s laptop. She turned toward him. “Your hard drive should now be a replica of Asher’s. Ready?”
“Fire it up.”
She pressed the power button and they both crowded around, watching the screen. For a moment, it remained black. Then there was a brief chirp and the OS splash screen appeared.
“Bingo,” Hui said softly.
Crane waited as she loaded a file management utility from one of her CDs and began exploring Asher’s documents.
“Everything appears to be intact,” she said. “No data dropouts.”
“What’s there?”
“It’s as I suspected. E-mail, a few scientific articles in progress. And then a large folder titled ‘decrypt.’”
“Take a look at that.”
Hui typed a series of commands. “It contains several utilities I’m not familiar with—probably language translators or decryption routines. There are three subdirectories, as well. One called ‘initial,’ another called ‘source,’ and a third called ‘target.’”
“Let’s see what’s in ‘initial.’”
Hui moved her mouse over the icon. “It contains just one file, ‘initial.txt.’ Let me bring it up.” She clicked the mouse and text window opened.
“Judging by the length,” she said, “I’ll bet it’s the very first signal the platform workers discovered, the high-frequency seismic ping. The one that led us here in the first place.”
“You mean, the one transmitted from beneath the Moho.”
“That’s right. Dr. Asher doesn’t seem to have made an attempt to decipher it.”
“He was concentrating on the signals the sentinels were transmitting. They were shorter, easier to work with. And my guess is they’re located in the ‘source’ subfolder.”
“Let’s check.” A brief pause. “Looks like you’re right. There are about forty files here, much shorter.”
“So Asher and Marris only parsed forty of the signals for decryption. What do you want to bet the other subfolder holds the translations?” Crane felt his excitement grow.
“I wouldn’t take that bet. Let’s check the contents.” Hui moused over the screen. A new folder opened, containing a list of the contents of “target”:
1_trans.txt
2_trans.txt
3_trans.txt
4_trans.txt
5_trans.txt
6_trans.txt
7_trans.txt
8_trans.txt
“There they are,” Hui said, her voice almost a whisper.
“So Asher and Marris had translated eight of the forty messages when they called me. Hurry, open the first one.”
Hui moused over the icon, clicked. A new text window opened, containing a single line:
x = 1/0
“Wait a minute,” Crane said. “There’s something wrong here. That’s Asher’s old, original translation. The one he got wrong.”
“I’ll say he got it wrong. Anybody who could build something as complex as those sentinels must know you can’t divide by zero.”
“He told me the decryption had gone so smoothly at first they figured they’d made some tiny mistake. So they wasted days trying to figure what they did wrong. When they went into the hyperbaric chamber, they’d given up on that and were taking a new direction entirely.” Crane frowned at the screen. “This is old news. There must be another folder somewhere.”
There was a pause while Hui consulted her file utility. “Nope. This is the only viable folder.”
“Take a look at the second file, then. Maybe he just didn’t bother to erase his wrong guess.”
Hui opened “2_trans.txt”:
x = 00
“Zero to the power of zero?” Crane said. “That’s just as undefined as division by zero.”
Another thought struck him. “Can you check the time and date stamp on those files?”
A few clicks of the mouse. “Yesterday afternoon.”
“All of them?”
“Yes.”
“That was when he was inside the chamber, all right. So they are new, after all.”
Crane lapsed into silence while Hui opened the six other files. Again and again, they were simple mathematical expressions; again and again, they were illogical, impossible.
a3+b3 =c3
x = a/b
x = In (0)
“A cubed, plus b cubed, equals c cubed?” Hui shook her head. “There are no three numbers that will satisfy that expression.”
“Or how about the natural logarithm of zero? Impossible. And pi is a transcendental number. You can’t define it by dividing one number into another.”
“And yet it seems Dr. Asher was right the first time. About the translations, I mean.”
“He clearly thought he was. But it makes no sense. Why would those sentinels be broadcasting a series of impossible mathematical expressions? And why would they consider them so important they’d be transmitting on every known frequency…and then some? I think that—”
Crane abruptly fell silent. From outside in the corridor he could hear muffled conversation, the sound of tramping feet.
He turned toward Hui. She looked back, eyes wide.
He pointed toward the back of the room. “Into that closet. Quickly.”
She ran to the equipment closet and slipped inside. Crane turned off the lights with a quick slap of his palm, then followed as quickly and silently as he could. At the last minute he stopped, stepped back out of the closet and into the room, and plucked the fire-suppressant drop cloth from its hook.
The footsteps came closer.
Crane spread the drop cloth as evenly as he could over the laptops and equipment on the table. Then he raced to the closet and shut them both in. A moment later, he heard the lab door open.
He peered out of the grille in the closet door. Two marines stood in the entrance of the lab, silhouetted by the glow of the corridor.
One of them snapped on the lights. Crane leaned back into the darkness. He could feel Hui’s warm, rapid breath on his neck.
Footsteps again as the marines stepped into the room. Then silence.
Slowly—very slowly—Crane leaned forward again, until he could just peer through the grille. He saw the marines standing by the lab table, doing a slow recon of the room.
“There’s nobody here,” one said. “Let’s try the next lab.”
“In a minute,” the other replied. “I want to check something out first.” And—with cautious deliberation—the man stepped toward the closet.
43
Crane shrank back into the darkness. Behind him, Hui caught her breath. He reached down, took her hand, squeezed it tightly.
The thin rays of light filtering through the grille were now obscured by the approaching figure. Crane heard t
he footsteps stop just outside the door.
Suddenly, a radio squawked. There was a brief fumbling, the snap of a button. “Barbosa,” came a voice, so close it seemed almost to come from inside the closet. Another brief squawk. Then: “Aye, aye, sir.”
“Let’s go,” Barbosa said.
“What is it?” asked the other marine.
“Korolis. There’s been a sighting.”
“Where?”
“Waste Reclamation. Come on, let’s move out.” There was the sound of retreating footsteps, the closing of a door—then silence once again.
Crane realized he was holding his breath. He let it out in a long, shuddering gasp. Then he released Hui’s hand and turned to face her.
Hui looked back, her eyes luminous in the dim light.
Five minutes passed without another word. Slowly, Crane felt his heartbeat return to its normal speed. At last, he put his hand on the closet door and pushed it quietly open. Legs still feeling like jelly, he emerged and switched the lights back on.
Hui pulled the drop cloth off the instruments and computers, her movements slow and mechanical. “What now?” she asked.
Crane tried to force his brain back on track. “We keep going.”
“But where? We’ve gone over all the decryptions. They’re just a lot of impossible math expressions.”
“What about that other file, ‘initial.txt’? The longer one that’s being transmitted from beneath the Moho. You’re sure there’s no translation on the laptop?”
Hui shook her head. “Positive. Like you said, Dr. Asher must have concentrated on the shorter ones the sentinels were emitting.”
Crane paused. Then he turned toward the laptop. “What could he have discovered?” he said, almost to himself. “He was beside himself with excitement when he called me from the oxygen chamber. There must be something.”
He turned back to Hui. “Can you retrace his final steps?”
She frowned. “How?”