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 were 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 preapproved 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 antiterrorist 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.”
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 a 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 antigovernment 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.”
“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?” 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.
Anarchy.
“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.”