Digital Fortress

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."

"Exactly."

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?"