Digital Fortress

Although she had practically lived in Crypto since its completion three years ago, the sight of it still amazed her. The main room was an enormous circular chamber that rose five stories. Its transparent, domed ceiling towered 120 feet at its central peak. The Plexiglas cupola was embedded with a polycarbonate mesh-a protective web capable of withstanding a two-megaton blast. The screen filtered the sunlight into delicate lacework across the walls. Tiny particles of dust drifted upward in wide unsuspecting spirals-captives of the dome's powerful deionizing system.

The room's sloping sides arched broadly at the top and then became almost vertical as they approached eye level. Then they became subtly translucent and graduated to an opaque black as they reached the floor-a shimmering expanse of polished black tile that shone with an eerie luster, giving one the unsettling sensation that the floor was transparent. Black ice.

Pushing through the center of the floor like the tip of a colossal torpedo was the machine for which the dome had been built. Its sleek black contour arched twenty-three feet in the air before plunging back into the floor below. Curved and smooth, it was as if an enormous killer whale had been frozen mid breach in a frigid sea.

This was TRANSLTR, the single most expensive piece of computing equipment in the world-a machine the NSA swore did not exist.

Like an iceberg, the machine hid 90 percent of its mass and power deep beneath the surface. Its secret was locked in a ceramic silo that went six stories straight down-a rocketlike hull surrounded by a winding maze of catwalks, cables, and hissing exhaust from the freon cooling system. The power generators at the bottom droned in a perpetual low-frequency hum that gave the acoustics in Crypto a dead, ghostlike quality.

***

TRANSLTR, like all great technological advancements, had been a child of necessity. During the 1980s, the NSA witnessed a revolution in telecommunications that would change the world of intelligence reconnaissance forever-public access to the Internet. More specifically, the arrival of E-mail.

Criminals, terrorists, and spies had grown tired of having their phones tapped and immediately embraced this new means of global communication. E-mail had the security of conventional mail and the speed of the telephone. Since the transfers traveled through underground fiber-optic lines and were never transmitted into the airwaves, they were entirely intercept-proof-at least that was the perception.

In reality, intercepting E-mail as it zipped across the Internet was child's play for the NSA's techno-gurus. The Internet was not the new home computer revelation that most believed. It had been created by the Department of Defense three decades earlier-an enormous network of computers designed to provide secure government communication in the event of nuclear war. The eyes and ears of the NSA were old Internet pros. People conducting illegal business via E-mail quickly learned their secrets were not as private as they'd thought. The FBI, DEA, IRS, and other U.S. law enforcement agencies-aided by the NSA's staff of wily hackers-enjoyed a tidal wave of arrests and convictions.

Of course, when the computer users of the world found out the U.S. government had open access to their E-mail communications, a cry of outrage went up. Even pen pals, using E-mail for nothing more than recreational correspondence, found the lack of privacy unsettling. Across the globe, entrepreneurial programmers began working on a way to keep E-mail more secure. They quickly found one and public-key encryption was born.

Public-key encryption was a concept as simple as it was brilliant. It consisted of easy-to-use, home-computer software that scrambled personal E-mail messages in such a way that they were totally unreadable. A user could write a letter and run it through the encryption software, and the text would come out the other side looking like random nonsense-totally illegible-a code. Anyone intercepting the transmission found only an unreadable garble on the screen.

The only way to unscramble the message was to enter the sender's "pass-key"-a secret series of characters that functioned much like a PIN number at an automatic teller. The pass-keys were generally quite long and complex; they carried all the information necessary to instruct the encryption algorithm exactly what mathematical operations to follow tore-create the original message.

A user could now send E-mail in confidence. Even if the transmission was intercepted, only those who were given the key could ever decipher it.

The NSA felt the crunch immediately. The codes they were facing were no longer simple substitution ciphers crackable with pencil and graph paper-they were computer-generated hash functions that employed chaos theory and multiple symbolic alphabets to scramble messages into seemingly hopeless randomness.