Susan waited for his point.
The commander stared wearily at the floor and then looked up. “Susan, hear me out,” he said, smiling tenderly at her. “You’ll want to stop me, but hear me out. I’ve been decrypting Tankado’s E‑mail for about two months now. As you can imagine, I was shocked when I first read his messages to North Dakota about an unbreakable algorithm called Digital Fortress. I didn’t believe it was possible. But every time I intercepted anew message, Tankado sounded more and more convincing. When I read that he’d used mutation strings to write a rotating key‑code, I realized he was light‑years ahead of us; it was an approach no one here had never tried.”
“Why would we?” Susan asked. “It barely makes sense.”
Strathmore stood up and started pacing, keeping one eye on the door. “A few weeks ago, when I heard about the Digital Fortress auction, I finally accepted the fact that Tankado was serious. I knew if he sold his algorithm to a Japanese software company, we were sunk, so I tried to think of any way I could stop him. I considered having him killed, but with all the publicity surrounding the algorithm and all his recent claims about TRANSLTR, we would be prime suspects. That’s when it dawned on me.” He turned to Susan. “I realized that Digital Fortress should not be stopped.”
Susan stared at him, apparently lost.
Strathmore went on. “I suddenly saw Digital Fortress as the opportunity of a lifetime. It hit me that with a few changes, Digital Fortress could work for us instead of against us.”
Susan had never heard anything so absurd. Digital Fortress was an unbreakable algorithm; it would destroy them.
“If,” Strathmore continued, “if I could just make a small modification in the algorithm . . . before it was released . . .” He gave her a cunning glint of the eye.
It took only an instant.
Strathmore saw the amazement register in Susan’s eyes. He excitedly explained his plan. “If I could get the pass‑key, I could unlock our copy of Digital Fortress and insert a modification.”
“A back door,” Susan said, forgetting the Commander had ever lied to her. She felt a surge of anticipation. “Just like Skipjack.”
Strathmore nodded. “Then we could replace Tankado’s give‑away file on the Internet with our altered version. Because Digital Fortress is a Japanese algorithm, no one will ever suspect the NSA had any part in it. All we have to do is make the switch.”
Susan realized the plan was beyond ingenious. It was pure . . . Strathmore. He planned to facilitate the release of an algorithm the NSA could break!
“Full access,” Strathmore said. “Digital Fortress will become the encryption standard overnight.”
“Overnight?” Susan said. “How do you figure that? Even if Digital Fortress becomes available everywhere for free, most computer users will stick with their old algorithms for convenience. Why would they switch to Digital Fortress?”
Strathmore smiled. “Simple. We have a security leak. The whole world finds out about TRANSLTR.”
Susan’s jaw dropped.
“Quite simply, Susan, we let the truth hit the street. We tell the world that the NSA has a computer that can break every algorithm except Digital Fortress.”
Susan was amazed. “So everyone jumps ship to Digital Fortress . . . not knowing we can break it!”
Strathmore nodded. “Exactly.” There was a long silence. “I’m sorry I lied to you. Trying to rewrite Digital Fortress is a pretty big play, I didn’t want you involved.”
“I . . . understand,” she replied slowly, still reeling from the brilliance of it all. “You’re not a bad liar.”
Strathmore chuckled. “Years of practice. Lying was the only way to keep you out of the loop.”
Susan nodded. “And how big a loop is it?”
“You’re looking at it.”
Susan smiled for the first time in an hour. “I was afraid you’d say that.”
He shrugged. “Once Digital Fortress is in place, I’ll brief the director.”
Susan was impressed. Strathmore’s plan was a global intelligence coup the magnitude of which had never before been imagined. And he’d attempted it single‑handedly. It looked like he might pull it off too. The pass‑key was downstairs. Tankado was dead. Tankado’s partner had been located.
Susan paused.
Tankado is dead. That seemed very convenient. She thought of all the lies that Strathmore had told her and felt a sudden chill. She looked uneasily at the commander. “Did you kill Ensei Tankado?”
Strathmore looked surprised. He shook his head. “Of course not. There was no need to kill Tankado. In fact, I’d prefer he were alive. His death could cast suspicion on Digital Fortress. I wanted this switch to go as smoothly and inconspicuously as possible. The original plan was to make the switch and let Tankado sell his key.”
Susan had to admit it made sense. Tankado would have no reason to suspect the algorithm on the Internet was not the original. Nobody had access to it except himself and North Dakota. Unless Tankado went back and studied the programming after it was released, he’d never know about the back door. He’d slaved over Digital Fortress for long enough that he’d probably never want to see the programming again.
Susan let it all soak in. She suddenly understood the commander’s need for privacy in Crypto. The task at hand was time‑consuming and delicate‑writing a concealed back door in a complex algorithm and making an undetected Internet switch. Concealment was of paramount importance. The simple suggestion that Digital Fortress was tainted could ruin the commander’s plan.
Only now did she fully grasp why he had decided to let TRANSLTR keep running. If Digital Fortress is going to be the NSA’s new baby, Strathmore wanted to be sure it was unbreakable!
“Still want out?” he asked.
Susan looked up. Somehow sitting there in the dark with the great Trevor Strathmore, her fears were swept away. Rewriting Digital Fortress was a chance to make history‑a chance to do incredible good‑and Strathmore could use her help. Susan forced a reluctant smile. “What’s our next move?”
Strathmore beamed. He reached over and put a hand on her shoulder. “Thanks.” He smiled and then got down to business. “We’ll go downstairs together.” He held up his Berretta. “You’ll search Hale’s terminal. I’ll cover you.”
Susan bristled at the thought of going downstairs. “Can’t we wait for David to call with Tankado’s copy?”
Strathmore shook his head. “The sooner we make the switch, the better. We have no guarantees that David will even find the other copy. If by some fluke the ring falls into the wrong hands over there, I’d prefer we’d already made the algorithm switch. That way, whoever ends up with the key will download our version of the algorithm.” Strathmore fingered his gun and stood. “We need to go for Hale’s key.”
Susan fell silent. The commander had a point. They needed Hale’s pass‑key. And they needed it now.
When Susan stood, her legs were jittery. She wished she’d hit Hale harder. She eyed Strathmore’s weapon and suddenly felt queasy. “You’d actually shoot Greg Hale?”
“No.” Strathmore frowned, striding to the door. “But let’s hope he doesn’t know that.”
CHAPTER 76
Outside the Seville airport terminal, a taxi sat idle, the meter running. The passenger in the wire‑rim glasses gazed through the plate‑glass windows of the well‑lit terminal. He knew he’d arrived in time.
He could see a blond girl. She was helping David Becker to a chair. Becker was apparently in pain. He does not yet know pain, the passenger thought. The girl pulled a small object from her pocket and held it out. Becker held it up and studied it in the light. Then he slipped it on his finger. He pulled a stack of bills from his pocket and paid the girl. They talked a few minutes longer, and then the girl hugged him. She waved, shouldered her duffel, and headed off across the concourse.