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Chapter 6

Although Ensei Tankado was not alive during the Second World War, he carefully studied everything about it-particularly about its culminating event, the blast in which 100,000 of his countrymen where incinerated by an atomic bomb.

Hiroshima, 8:15 a.m. August 6, 1945-a vile act of destruction. A senseless display of power by a country that had already won the war. Tankado had accepted all that. But what he could never accept was that the bomb had robbed him of ever knowing his mother. She had died giving birth to him-complications brought on by the radiation poisoning she’d suffered so many years earlier.

In 1945, before Ensei was born, his mother, like many of her friends, traveled to Hiroshima to volunteer in the burn centers. It was there that she became one of the hibakusha-the radiated people. Nineteen years later, at the age of thirty-six, as she lay in the delivery room bleeding internally, she knew she was finally going to die. What she did not know was that death would spare her the final horror-her only child was to be born deformed.

Ensei’s father never even saw his son. Bewildered by the loss of his wife and shamed by the arrival of what the nurses told him was an imperfect child who probably would not survive the night, he disappeared from the hospital and never came back. Ensei Tankado was placed in a foster home.

Every night the young Tankado stared down at the twisted fingers holding his daruma wish-doll and swore he’d have revenge-revenge against the country that had stolen his mother and shamed his father into abandoning him. What he didn’t know was that destiny was about to intervene.

In February of Ensei’s twelfth year, a computer manufacturer in Tokyo called his foster family and asked if their crippled child might take part in a test group for a new keyboard they’d developed for handicapped children. His family agreed.

Although Ensei Tankado had never seen a computer, it seemed he instinctively knew how to use it. The computer opened worlds he had never imagined possible. Before long it became his entire life. As he got older, he gave classes, earned money, and eventually earned a scholarship to Doshisha University. Soon Ensei Tankado was known across Tokyo as fugusha kisai-the crippled genius.

Tankado eventually read about Pearl Harbor and Japanese war crimes. His hatred of America slowly faded. He became a devout Buddhist. He forgot his childhood vow of revenge; forgiveness was the only path to enlightenment.

By the time he was twenty, Ensei Tankado was somewhat of an underground cult figure among programmers. IBM offered him a work visa and a post in Texas. Tankado jumped at the chance. Three years later he had left IBM, was living in New York, and was writing software on his own. He rode the new wave of public-key encryption. He wrote algorithms and made a fortune.

Like many of the top authors of encryption algorithms, Tankado was courted by the NSA. The irony was not lost on him-the opportunity to work in the heart of the government in a country he had once vowed to hate. He decided to go on the interview. Whatever doubts he had disappeared when he met Commander Strathmore. They talked frankly about Tankado’s background, the potential hostility he might feel toward the U.S., his plans for the future. Tankado took a polygraph test and underwent five weeks of rigorous psychological profiles. He passed them all. His hatred had been replaced by his devotion to Buddha. Four months later Ensei Tankado went to work in the Cryptography Department of the National Security Agency.

Despite his large salary, Tankado went to work on an old Moped and ate a bag lunch alone at his desk instead of joining the rest of the department for prime rib and vichyssoise in the commissary. The other cryptographers revered him. He was brilliant-as creative a programmer as any of them had ever seen. He was kind and honest, quiet, and of impeccable ethics. Moral integrity was of paramount importance to him. It was for this reason that his dismissal from the NSA and subsequent deportation had been such a shock.

Tankado, like the rest of the Crypto staff, had been working on the TRANSLTR project with the understanding that if successful, it would be used to decipher E-mail only in cases pre-approved by the Justice Department. The NSA’s use of TRANSLTR was to be regulated in much the same way the FBI needed a federal court order to install a wiretap. TRANSLTR was to include programming that called for passwords held in escrow by the Federal Reserve and the Justice Department in order to decipher a file. This would prevent the NSA from listening indiscriminately to the personal communications of law-abiding citizens around the globe.

However, when the time came to enter that programming, the TRANSLTR staff was told there had been a change of plans. Because of the time pressures often associated with the NSA’s anti-terrorist work, TRANSLTR was to be a free-standing decryption device whose day-to-day operation would be regulated solely by the NSA.

Ensei Tankado was outraged. This meant the NSA would, in effect, be able to open everyone’s mail and reseal it without their knowing. It was like having a bug in every phone in the world. Strathmore attempted to make Tankado see TRANSLTR as a law-enforcement device, but it was no use; Tankado was adamant that it constituted a gross violation of human rights. He quit on the spot and within hours violated the NSA’s code of secrecy by trying to contact the Electronic Frontier Foundation. Tankado stood poised to shock the world with his story of a secret machine capable of exposing computer users around the world to unthinkable government treachery. The NSA had had no choice but to stop him.

Tankado’s capture and deportation, widely publicized among on-line newsgroups, had been an unfortunate public shaming. Against Strathmore’s wishes, the NSA damage-control specialists-nervous that Tankado would try to convince people of TRANSLTR’s existence-generated rumors that destroyed his credibility. Ensei Tankado was shunned by the global computer community-nobody trusted a cripple accused of spying, particularly when he was trying to buy his freedom with absurd allegations about a U.S. code-breaking machine.

The oddest thing of all was that Tankado seemed to understand; it was all part of the intelligence game. He appeared to harbor no anger, only resolve. As security escorted him away, Tankado spoke his final words to Strathmore with a chilling calm.

“We all have a right to keep secrets,” he’d said. “Someday I’ll see to it we can.”

Chapter 7

Susan’s mind was racing-Ensei Tankado wrote a program that creates unbreakable codes! She could barely grasp the thought.

“Digital Fortress,” Strathmore said. “That’s what he’s calling it. It’s the ultimate counterintelligence weapon. If this program hits the market, every third grader with a modem will be able to send codes the NSA can’t break. Our intelligence will be shot.”

But Susan’s thoughts were far removed from the political implications of Digital Fortress. She was still struggling to comprehend its existence. She’d spent her life breaking codes, firmly denying the existence of the ultimate code. Every code is breakable-the Bergofsky Principle! She felt like an atheist coming face to face with God.

“If this code gets out,” she whispered, “cryptography will become a dead science.”

Strathmore nodded. “That’s the least of our problems.”

“Can we pay Tankado off? I know he hates us, but can’t we offer him a few million dollars? Convince him not to distribute?”

Strathmore laughed. “A few million? Do you know what this thing is worth? Every government in the world will bid top dollar. Can you imagine telling the President that we’re still cable-snooping the Iraqis but we can’t read the intercepts anymore? This isn’t just about the NSA, it’s about the entire intelligence community. This facility provides support for everyone-the FBI, CIA, DEA; they’d all be flying blind. The drug cartels’ shipments would become untraceable, major corporations could transfer money with no paper trail and leave the IRS out in the cold, terrorists could chat in total secrecy-it would be chaos.”

“The EFF will have field day,” Susan said, pale.

“The EFF doesn’t have the first clue about what we do here,” Strathmore railed in disgust. “If they knew how many terrorist attacks we’ve stopped because we can decrypt codes, they’d change their tune.”

Susan agreed, but she also knew the realities; the EFF would never know how important TRANSLTR was. TRANSLTR had helped foil dozens of attacks, but the information was highly classified and would never be released. The rationale behind the secrecy was simple: The government could not afford the mass hysteria caused by revealing the truth; no one knew how the public would react to the news that there had been two nuclear close calls by fundamentalist groups on U.S. soil in the last year.

Nuclear attack, however, was not the only threat. Only last month TRANSLTR had thwarted one of the most ingeniously conceived terrorist attacks the NSA had ever witnessed. An anti-government organization had devised a plan, code-named Sherwood Forest. It targeted the New York Stock Exchange with the intention of “redistributing the wealth.” Over the course of six days, members of the group placed twenty-seven nonexplosive flux pods in the buildings surrounding the Exchange. These devices, when detonated, create a powerful blast of magnetism. The simultaneous discharge of these carefully placed pods would create a magnetic field so powerful that all magnetic media in the Stock Exchange would be erased-computer hard drives, massive ROM storage banks, tape backups, and even floppy disks. All records of who owned what would disintegrate permanently.

Because pinpoint timing was necessary for simultaneous detonation of the devices, the flux pods were interconnected over Internet telephone lines. During the two-day countdown, the pods’ internal clocks exchanged endless streams of encrypted synchronization data. The NSA intercepted the data-pulses as a network anomaly but ignored them as a seemingly harmless exchange of gibberish. But after TRANSLTR decrypted the data streams, analysts immediately recognized the sequence as a network-synchronized countdown. The pods were located and removed a full three hours before they were scheduled to go off.

Susan knew that without TRANSLTR the NSA was helpless against advanced electronic terrorism. She eyed the Run-Monitor. It still read over fifteen hours. Even if Tankado’s file broke right now, the NSA was sunk. Crypto would be relegated to breaking less than two codes a day. Even at the present rate of 150 a day, there was still a backlog of files awaiting decryption.

“Tankado called me last month,” Strathmore said, interrupting Susan’s thoughts.

Susan looked up. “Tankado called you?”

He nodded. “To warn me.”

“Warn you? He hates you.”

“He called to tell me he was perfecting an algorithm that wrote unbreakable codes. I didn’t believe him.”

“But why would he tell you about it?” Susan demanded. “Did he want you to buy it?”

“No. It was blackmail.”

Things suddenly began falling into place for Susan. “Of course,” she said, amazed. “He wanted you to clear his name.”

“No,” Strathmore frowned. “Tankado wanted TRANSLTR.”


“Yes. He ordered me to go public and tell the world we have TRANSLTR. He said if we admitted we can read public E-mail, he would destroy Digital Fortress.”

Susan looked doubtful.

Strathmore shrugged. “Either way, it’s too late now. He’s posted a complimentary copy of Digital Fortress at his Internet site. Everyone in the world can download it.”

Susan went white. “He what!”

“It’s a publicity stunt. Nothing to worry about. The copy he posted is encrypted. People can download it, but nobody can open it. It’s ingenious, really. The source code for Digital Fortress has been encrypted, locked shut.”

Susan looked amazed. “Of course! So everybody can have a copy, but nobody can open it.”

“Exactly. Tankado’s dangling a carrot.”

“Have you seen the algorithm?”

The commander looked puzzled. “No, I told you it’s encrypted.”

Susan looked equally puzzled. “But we’ve got TRANSLTR; why not just decrypt it?” But when Susan saw Strathmore’s face, she realized the rules had changed. “Oh my God.” She gasped, suddenly understanding. “Digital Fortress is encrypted with itself?”

Strathmore nodded. “Bingo.”

Susan was amazed. The formula for Digital Fortress had been encrypted using Digital Fortress. Tankado had posted a priceless mathematical recipe, but the text of the recipe had been scrambled. And it had used itself to do the scrambling.

“It’s Biggleman’s Safe,” Susan stammered in awe.

Strathmore nodded. Biggleman’s Safe was a hypothetical cryptography scenario in which a safe builder wrote blueprints for an unbreakable safe. He wanted to keep the blueprints a secret, so he built the safe and locked the blueprints inside. Tankado had done the same thing with Digital Fortress. He’d protected his blueprints by encrypting them with the formula outlined in his blueprints.

“And the file in TRANSLTR?” Susan asked.

“I downloaded it from Tankado’s Internet site like everyone else. The NSA is now the proud owner of the Digital Fortress algorithm; we just can’t open it.”

Susan marveled at Ensei Tankado’s ingenuity. Without revealing his algorithm, he had proven to the NSA that it was unbreakable.

Strathmore handed her a newspaper clipping. It was a translated blurb from the Nikkei Shimbun, the Japanese equivalent of the Wall Street Journal, stating that the Japanese programmer Ensei Tankado had completed a mathematical formula he claimed could write unbreakable codes. The formula was called Digital Fortress and was available for review on the Internet. The programmer would be auctioning it off to the highest bidder. The column went on to say that although there was enormous interest in Japan, the few U.S. software companies who had heard about Digital Fortress deemed the claim preposterous, akin to turning lead to gold. The formula, they said, was a hoax and not to be taken seriously.

Susan looked up. “An auction?”

Strathmore nodded. “Right now every software company in Japan has downloaded an encrypted copy of Digital Fortress and is trying to crack it open. Every second they can’t, the bidding price climbs.”

“That’s absurd,” Susan shot back. “All the new encrypted files are uncrackable unless you have TRANSLTR. Digital Fortress could be nothing more than a generic, public-domain algorithm, and none of these companies could break it.”

“But it’s a brilliant marketing ploy,” Strathmore said. “Think about it-all brands of bulletproof glass stop bullets, but if a company dares you to put a bullet through theirs, suddenly everybody’s trying.”

“And the Japanese actually believe Digital Fortress is different? Better than everything else on the market?”

“Tankado may have been shunned, but everybody knows he’s a genius. He’s practically a cult icon among hackers. If Tankado says the algorithm’s unbreakable, it’s unbreakable.”

But they’re all unbreakable as far as the public knows!”

“Yes…” Strathmore mused. “For the moment.”

“What’s that supposed to mean?”

Strathmore sighed. “Twenty years ago no one imagined we’d be breaking twelve-bit stream ciphers. But technology progressed. It always does. Software manufacturers assume at some point computers like TRANSLTR will exist. Technology is progressing exponentially, and eventually current public-key algorithms will lose their security. Better algorithms will be needed to stay ahead of tomorrow’s computers.”

“And Digital Fortress is it?”

“Exactly. An algorithm that resists brute force will never become obsolete, no matter how powerful code-breaking computers get. It could become a world standard overnight.”

Susan pulled in a long breath. “God help us,” she whispered. “Can we make a bid?”

Strathmore shook his head. “Tankado gave us our chance. He made that clear. It’s too risky anyway; if we get caught, we’re basically admitting that we’re afraid of his algorithm. We’d be making a public confession not only that we have TRANSLTR but that Digital Fortress is immune.”

“What’s the time frame?”

Strathmore frowned. “Tankado planned to announce the highest bidder tomorrow at noon.”

Susan felt her stomach tighten. “Then what?”

“The arrangement was that he would give the winner the pass-key.”

“The pass-key?”

“Part of the ploy. Everybody’s already got the algorithm, so Tankado’s auctioning off the pass-key that unlocks it.”

Susan groaned. “Of course.” It was perfect. Clean and simple. Tankado had encrypted Digital Fortress, and he alone held the pass-key that unlocked it. She found it hard to fathom that somewhere out there-probably scrawled on a piece of paper in Tankado’s pocket-there was a sixty-four-character pass-key that could end U.S. intelligence gathering forever.

Susan suddenly felt ill as she imagined the scenario. Tankado would give his pass-key to the highest bidder, and that company would unlock the Digital Fortress file. Then it probably would embed the algorithm in a tamper-proof chip, and within five years every computer would come preloaded with a Digital Fortress chip. No commercial manufacturer had ever dreamed of creating an encryption chip because normal encryption algorithms eventually become obsolete. But Digital Fortress would never become obsolete; with a rotating cleartext function, no brute-force attack would ever find the right key. A new digital encryption standard. From now until forever. Every code unbreakable. Bankers, brokers, terrorists, spies. One world-one algorithm.


“What are the options?” Susan probed. She was well aware that desperate times called for desperate measures, even at the NSA.

“We can’t remove him, if that’s what you’re asking.”

It was exactly what Susan was asking. In her years with the NSA, Susan had heard rumors of its loose affiliations with the most skilled assassins in the world-hired hands brought in to do the intelligence community’s dirty work.

Strathmore shook his head. “Tankado’s too smart to leave us an option like that.”

Susan felt oddly relieved. “He’s protected?”

“Not exactly.”

“In hiding?”

Strathmore shrugged. “Tankado left Japan. He planned to check his bids by phone. But we know where he is.”

“And you don’t plan to make a move?”

“No. He’s got insurance. Tankado gave a copy of his pass-key to an anonymous third party… in case anything happened.”

Of course, Susan marveled. A guardian angel. “And I suppose if anything happens to Tankado, the mystery man sells the key?”

“Worse. Anyone hits Tankado, and his partner publishes.”

Susan looked confused. “His partner publishes the key?”

Strathmore nodded. “Posts it on the Internet, puts it in newspapers, on billboards. In effect, he gives it away.”

Susan’s eyes widened. “Free downloads?”

“Exactly. Tankado figured if he was dead, he wouldn’t need the money-why not give the world a little farewell gift?”

There was a long silence. Susan breathed deeply as if to absorb the terrifying truth. Ensei Tankado has created an unbreakable algorithm. He’s holding us hostage.

She suddenly stood. Her voice was determined. “We must contact Tankado! There must be a way to convince him not to release! We can offer him triple the highest bid! We can clear his name! Anything!”

“Too late,” Strathmore said. He took a deep breath. “Ensei Tankado was found dead this morning in Seville, Spain.”

Chapter 8

The twin-engine Learjet 60 touched down on the scorching runway. Outside the window, the barren landscape of Spain’s lower extremadura blurred and then slowed to a crawl.

“Mr. Becker?” a voice crackled. “We’re here.”

Becker stood and stretched. After unlatching the overhead compartment, he remembered he had no luggage. There had been no time to pack. It didn’t matter-he’d been promised the trip would be brief, in and out.

As the engines wound down, the plane eased out of the sun and into a deserted hangar opposite the main terminal. A moment later the pilot appeared and popped the hatch. Becker tossed back the last of his cranberry juice, put the glass on the wet bar, and scooped up his suit coat.

The pilot pulled a thick manila envelope from his flight suit. “I was instructed to give you this.” He handed it to Becker. On the front, scrawled in blue pen, were the words:


Becker thumbed through the thick stack of reddish bills. “What the…?”

“Local currency,” the pilot offered flatly.

“I know what it is,” Becker stammered. “But it’s… it’s too much. All I need is taxi fare.” Becker did the conversion in his head. “What’s in here is worth thousands of dollars!”

“I have my orders, sir.” The pilot turned and hoisted himself back into the cabin. The door slid shut behind him.

Becker stared up at the plane and then down at the money in his hand. After standing a moment in the empty hangar, he put the envelope in his breast pocket, shouldered his suit coat, and headed out across the runway. It was a strange beginning. Becker pushed it from his mind. With a little luck he’d be back in time to salvage some of his Stone Manor trip with Susan.

In and out, he told himself. In and out.

There was no way he could have known.

Chapter 9

Systems security technician Phil Chartrukian had only intended to be inside Crypto a minute-just long enough to grab some paperwork he’d forgotten the day before. But it was not to be.

After making his way across the Crypto floor and stepping into the Sys-Sec lab, he immediately knew something was not right. The computer terminal that perpetually monitored TRANSLTR’s internal workings was unmanned and the monitor was switched off.

Chartrukian called out, “Hello?”

There was no reply. The lab was spotless-as if no one had been there for hours.

Although Chartrukian was only twenty-three and relatively new to the Sys-Sec squad, he’d been trained well, and he knew the drill: There was always a Sys-Sec on duty in Crypto… especially on Saturdays when no cryptographers were around.

He immediately powered up the monitor and turned to the duty board on the wall. “Who’s on watch?” he demanded aloud, scanning the list of names. According to the schedule, a young rookie named Seidenberg was supposed to have started a double shift at midnight the night before. Chartrukian glanced around the empty lab and frowned. “So where the hell is he?”

As he watched the monitor power up, Chartrukian wondered if Strathmore knew the Sys-Sec lab was unmanned. He had noticed on his way in that the curtains of Strathmore’s workstation were closed, which meant the boss was in-not at all uncommon for a Saturday; Strathmore, despite requesting his cryptographers take Saturdays off, seemed to work 365 days a year.

There was one thing Chartrukian knew for certain-if Strathmore found out the Sys-Sec lab was unmanned, it would cost the absent rookie his job. Chartrukian eyed the phone, wondering if he should call the young techie and bail him out; there was an unspoken rule among Sys-Sec that they would watch each other’s backs. In Crypto, Sys-Secs were second-class citizens, constantly at odds with the lords of the manor. It was no secret that the cryptographers ruled this multibillion-dollar roost; Sys-Secs were tolerated only because they kept the toys running smoothly.

Chartrukian made his decision. He grabbed the phone. But the receiver never reached his ear. He stopped short, his eyes transfixed on the monitor now coming into focus before him. As if in slow motion, he set down the phone and stared in open-mouthed wonder.

In eight months as a Sys-Sec, Phil Chartrukian had never seen TRANSLTR’s Run-Monitor post anything other than a double zero in the hours field. Today was a first.

TIME ELAPSED: 15:17:21

“Fifteen hours and seventeen minutes?” he choked. “Impossible!”

He rebooted the screen, praying it hadn’t refreshed properly. But when the monitor came back to life, it looked the same.

Chartrukian felt a chill. Crypto’s Sys-Secs had only one responsibility: Keep TRANSLTR “clean”-virus free.

Chartrukian knew that a fifteen-hour run could only mean one thing-infection. An impure file had gotten inside TRANSLTR and was corrupting the programming. Instantly his training kicked in; it no longer mattered that the Sys-Sec lab had been unmanned or the monitors switched off. He focused on the matter at hand-TRANSLTR. He immediately called up a log of all the files that had entered TRANSLTR in the last forty-eight hours. He began scanning the list.

Did an infected file get through? he wondered. Could the security filters have missed something?

As a precaution, every file entering TRANSLTR had to pass through what was known as Gauntlet-a series of powerful circuit-level gateways, packet filters, and disinfectant programs that scanned inbound files for computer viruses and potentially dangerous subroutines. Files containing programming “unknown” to Gauntlet were immediately rejected. They had to be checked by hand. Occasionally Gauntlet rejected entirely harmless files on the basis that they contained programming the filters had never seen before. In that case, the Sys-Secs did a scrupulous manual inspection, and only then, on confirmation that the file was clean, did they bypass Gauntlet’s filters and send the file into TRANSLTR.

Computer viruses were as varied as bacterial viruses. Like their physiological counterparts, computer viruses had one goal-to attach themselves to a host system and replicate. In this case, the host was TRANSLTR.

Chartrukian was amazed the NSA hadn’t had problems with viruses before. Gauntlet was a potent sentry, but still, the NSA was a bottom feeder, sucking in massive amounts of digital information from systems all over the world. Snooping data was a lot like having indiscriminate sex-protection or no protection, sooner or later you caught something.

Chartrukian finished examining the file list before him. He was now more puzzled than before. Every file checked out. Gauntlet had seen nothing out of the ordinary, which meant the file in TRANSLTR was totally clean.

“So what the hell’s taking so long?” he demanded of the empty room. Chartrukian felt himself break a sweat. He wondered if he should go disturb Strathmore with the news.

“A virus probe,” Chartrukian said firmly, trying to calm himself down. “I should run a virus probe.”

Chartrukian knew that a virus probe would be the first thing Strathmore would request anyway. Glancing out at the deserted Crypto floor, Chartrukian made his decision. He loaded the viral probe software and launched it. The run would take about fifteen minutes.

“Come back clean,” he whispered. “Squeaky clean. Tell Daddy it’s nothing.”

But Chartrukian sensed it was not “nothing.” Instinct told him something very unusual was going on inside the great decoding beast.

Chapter 10

“Ensei Tankado is dead?” Susan felt a wave of nausea. “You killed him? I thought you said-”

“We didn’t touch him,” Strathmore assured her. “He died of a heart attack. COMINT phoned early this morning. Their computer flagged Tankado’s name in a Seville police log through Interpol.”

“Heart attack?” Susan looked doubtful. “He was thirty years old.”

“Thirty-two,” Strathmore corrected. “He had a congenital heart defect.”

“I’d never heard that.”

“Turned up in his NSA physical. Not something he bragged about.”

Susan was having trouble accepting the serendipity of the timing. “A defective heart could kill him-just like that?” It seemed too convenient.

Strathmore shrugged. “Weak heart… combine it with the heat of Spain. Throw in the stress of blackmailing the NSA….”

Susan was silent a moment. Even considering the conditions, she felt a pang of loss at the passing of such a brilliant fellow cryptographer. Strathmore’s gravelly voice interrupted her thoughts.

“The only silver lining on this whole fiasco is that Tankado was traveling alone. Chances are good his partner doesn’t know yet he’s dead. The Spanish authorities said they’d contain the information for as long as possible. We only got the call because COMINT was on the ball.” Strathmore eyed Susan closely. “I’ve got to find the partner before he finds out Tankado’s dead. That’s why I called you in. I need your help.”

Susan was confused. It seemed to her that Ensei Tankado’s timely demise had solved their entire problem. “Commander,” she argued, “if the authorities are saying he died of a heart attack, we’re off the hook; his partner will know the NSA is not responsible.”

“Not responsible?” Strathmore’s eyes widened in disbelief. “Somebody blackmails the NSA and turns up dead a few days later-and we’re not responsible? I’d bet big money Tankado’s mystery friend won’t see it that way. Whatever happened, we look guilty as hell. It could easily have been poison, a rigged autopsy, any number of things.” Strathmore paused. “What was your first reaction when I told you Tankado was dead?”

She frowned. “I thought the NSA had killed him.”

“Exactly. If the NSA can put five Rhyolite satellites in geosynchronous orbit over the Mideast, I think it’s safe to assume we have the resources to pay off a few Spanish policemen.” The commander had made his point.

Susan exhaled. Ensei Tankado is dead. The NSA will be blamed. “Can we find his partner in time?”

“I think so. We’ve got a good lead. Tankado made numerous public announcements that he was working with a partner. I think he hoped it would discourage software firms from doing him any harm or trying to steal his key. He threatened that if there was any foul play, his partner would publish the key, and all firms would suddenly find themselves in competition with free software.”

“Clever.” Susan nodded.

Strathmore went on. “A few times, in public, Tankado referred to his partner by name. He called him North Dakota.”

“North Dakota? Obviously an alias of some sort.”

“Yes, but as a precaution I ran an Internet inquiry using North Dakota as a search string. I didn’t think I’d find anything, but I turned up an E-mail account.” Strathmore paused. “Of course I assumed it wasn’t the North Dakota we were looking for, but I searched the account just to be sure. Imagine my shock when I found the account was full of E-mail from Ensei Tankado.” Strathmore raised his eyebrows. “And the messages were full of references to Digital Fortress and Tankado’s plans to blackmail the NSA.”

Susan gave Strathmore a skeptical look. She was amazed the commander was letting himself be played with so easily. “Commander,” she argued, “Tankado knows full well the NSA can snoop E-mail from the Internet; he would never use E-mail to send secret information. It’s a trap. Ensei Tankado gave you North Dakota. He knew you’d run a search. Whatever information he’s sending, he wanted you to find-it’s a false trail.”

“Good instinct,” Strathmore fired back, “except for a couple of things. I couldn’t find anything under North Dakota, so I tweaked the search string. The account I found was under a variation-NDAKOTA.”

Susan shook her head. “Running permutations is standard procedure. Tankado knew you’d try variations until you hit something. NDAKOTA’s far too easy an alteration.”

“Perhaps,” Strathmore said, scribbling words on apiece of paper and handing it to Susan. “But look at this.”

Susan read the paper. She suddenly understood the Commander’s thinking. On the paper was North Dakota’s E-mail address.

NDAKOTA@ara.anon.org It was the letters ARA in the address that had caught Susan’s eye. ARA stood for American Remailers Anonymous, a well-known anonymous server.

Anonymous servers were popular among Internet users who wanted to keep their identities secret. For a fee, these companies protected an E-mailer’s privacy by acting as a middleman for electronic mail. It was like having a numbered post office box-a user could send and receive mail without ever revealing his true address or name. The company received E-mail addressed to aliases and then forwarded it to the client’s real account. The remailing company was bound by contract never to reveal the identity or location of its real users.

“It’s not proof,” Strathmore said. “But it’s pretty suspicious.”

Susan nodded, suddenly more convinced. “So you’re saying Tankado didn’t care if anybody searched for North Dakota because his identity and location are protected by ARA.”


Susan schemed for a moment. “ARA services mainly U.S. accounts. You think North Dakota might be over here somewhere?”

Strathmore shrugged. “Could be. With an American partner, Tankado could keep the two pass-keys separated geographically. Might be a smart move.”

Susan considered it. She doubted Tankado would have shared his pass-key with anyone except a very close friend, and as she recalled, Ensei Tankado didn’t have many friends in the States.

“North Dakota,” she mused, her cryptological mind mulling over the possible meanings of the alias. “What does his E-mail to Tankado sound like?”

“No idea. COMINT only caught Tankado’s outbound. At this point all we have on North Dakota is an anonymous address.”

Susan thought a minute. “Any chance it’s a decoy?”

Strathmore raised an eyebrow. “How so?”

“Tankado could be sending bogus E-mail to a dead account in hopes we’d snoop it. We’d think he’s protected, and he’d never have to risk sharing his pass-key. He could be working alone.”

Strathmore chuckled, impressed. “Tricky idea, except for one thing. He’s not using any of his usual home or business Internet accounts. He’s been dropping by Doshisha University and logging on to their mainframe. Apparently he’s got an account there that he’s managed to keep secret. It’s a very well-hidden account, and I found it only by chance.” Strathmore paused. “So… if Tankado wanted us to snoop his mail, why would he use a secret account?”

Susan contemplated the question. “Maybe he used a secret account so you wouldn’t suspect a ploy? Maybe Tankado hid the account just deep enough that you’d stumble on to it and think you got lucky. It gives his E-mail credibility.”

Strathmore chuckled. “You should have been a field agent. The idea’s a good one. Unfortunately, every letter Tankado sends gets a response. Tankado writes, his partner responds.”

Susan frowned. “Fair enough. So, you’re saying North Dakota’s for real.”

“Afraid so. And we’ve got to find him. And quietly. If he catches wind that we’re onto him, it’s all over.”

Susan now knew exactly why Strathmore had called her in. “Let me guess,” she said. “You want me to snoop ARA’s secure database and find North Dakota’s real identity?”

Strathmore gave her a tight smile. “Ms. Fletcher, you read my mind.”

When it came to discreet Internet searches, Susan Fletcher was the woman for the job. A year ago, a senior White House official had been receiving E-mail threats from someone with an anonymous E-mail address. The NSA had been asked to locate the individual. Although the NSA had the clout to demand the remailing company reveal the user’s identity, it opted for a more subtle method-a “tracer.”

Susan had created, in effect, a directional beacon disguised as a piece of E-mail. She could send it to the user’s phony address, and the remailing company, performing the duty for which it had been contracted, would forward it to the user’s real address. Once there, the program would record its Internet location and send word back to the NSA. Then the program would disintegrate without a trace. From that day on, as far as the NSA was concerned, anonymous remailers were nothing more than a minor annoyance.

“Can you find him?” Strathmore asked.

“Sure. Why did you wait so long to call me?”

“Actually”-he frowned-“I hadn’t planned on calling you at all. I didn’t want anyone else in the loop. I tried to send a copy of your tracer myself, but you wrote the damn thing in one of those new hybrid languages; I couldn’t get it to work. It kept returning nonsensical data. I finally had to bite the bullet and bring you in.”

Susan chuckled. Strathmore was a brilliant cryptographic programmer, but his repertoire was limited primarily to algorithmic work; the nuts and bolts of less lofty “secular” programming often escaped him. What was more, Susan had written her tracer in a new, crossbreed programming language called LIMBO; it was understandable that Strathmore had encountered problems. “I’ll take care of it.” She smiled, turning to leave. “I’ll be at my terminal.”

“Any idea on a time frame?”

Susan paused. “Well… it depends on how efficiently ARA forwards their mail. If he’s here in the States and uses something like AOL or CompuServe, I’ll snoop his credit card and get a billing address within the hour. If he’s with a university or corporation, it’ll take a little longer.” She smiled uneasily. “After that, the rest is up to you.”

Susan knew that “the rest” would be an NSA strike team, cutting power to the guy’s house and crashing through his windows with stun guns. The team would probably think it was on a drug bust. Strathmore would undoubtedly stride through the rubble himself and locate the sixty-four-character pass-key. Then he would destroy it. Digital Fortress would languish forever on the Internet, locked for all eternity.

“Send the tracer carefully,” Strathmore urged. “If North Dakota sees we’re onto him, he’ll panic, and I’ll never get a team there before he disappears with the key.”

“Hit and run,” she assured. “The moment this thing finds his account, it’ll dissolve. He’ll never know we were there.”

The commander nodded tiredly. “Thanks.”

Susan gave him a soft smile. She was always amazed how even in the face of disaster Strathmore could muster a quiet calm. She was convinced it was this ability that had defined his career and lifted him to the upper echelons of power.

As Susan headed for the door, she took a long look down at TRANSLTR. The existence of an unbreakable algorithm was a concept she was still struggling to grasp. She prayed they’d find North Dakota in time.

“Make it quick,” Strathmore called, “and you’ll be in the Smoky Mountains by nightfall.”

Susan froze in her tracks. She knew she had never mentioned her trip to Strathmore. She wheeled. Is the NSA tapping my phone?

Strathmore smiled guiltily. “David told me about your trip this morning. He said you’d be pretty ticked about postponing it.”

Susan was lost. “You talked to David this morning?”

“Of course.” Strathmore seemed puzzled by Susan’s reaction. “I had to brief him.”

“Brief him?” she demanded. “For what?”

“For his trip. I sent David to Spain.”

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