Espionage

During the Cold War, the invisible troops of the intelligence agencies carried out a variety of tasks at the bidding of their political masters. These jobs included assassination and destabilizing unfriendly regimes. But the core of espionage is gathering information and by definition, that goal must be accomplished in secret.

Some tools and missions could be concealed simply by placing them far away from the target -- the approach taken by surveillance planes and satellites.

But satellites can only go so far, and old-fashioned human intelligence must come into play. Like "Q," the master engineer in the James Bond films, engineers at every spy agency labored to produce tools for their spies in the field -- devices that could escape detection or, if they could not be hidden, looked like anything but what they were.

Some of their inventions seem almost quaint today: A two-way radio that could fit in a briefcase! A tape recorder that could be concealed under clothing! Throughout the Cold War, the demands of espionage helped drive familiar trends in technology -- making both exotic and everyday items more sophisticated, smaller, and more concealable.

U-2

U.S. Air Force photo

The U-2 spy plane was a mainstay of U.S. intelligence throughout the Cold War. First flown in 1955, it is in use today for high-altitude surveillance; weapons monitoring in Iraq was one recent high-profile mission.

Despite its age, the plane is still impressive; its wingspan, at 103 feet, is nearly twice its length.

The U-2 has a range of about 7,000 miles, long enough to fly from New York to Moscow nonstop with room to spare. It can fly above 70,000 feet, more than 13 miles above the Earth.

The U-2 had the world's highest-resolution camera, designed by Edwin Land, who would later become famous for his invention of the Polaroid instant camera.

The U-2's cover was blown in 1960, when Francis Gary Powers' plane was shot down over the U.S.S.R. As overflights of the Soviet Union became increasingly risky, much of the U-2's job was taken over by satellite surveillance (see Corona).

SR-71

U.S. Air Force photo

The SR-71, unofficially designated the "Blackbird," held the records for both altitude and speed for most of its nearly 24-year career. First flown in 1964, it remains -- as far as is publicly known -- the premier surveillance plane in the skies.

Officially, the SR-71 is listed as having a top speed of Mach 3.5, three and a half times the speed of sound, and a top altitude of 85,000 feet.

At its top altitude, the SR-71 can survey 100,000 square miles of terrain per hour, and it can fly from New York to Los Angeles in about an hour.

The Blackbird was a product of the famed Lockheed (now Lockheed Martin) "Skunk Works," a secretive group of engineers who operate with scant publicity and minimal interference from corporate management. The Skunk Works also built the U-2, the B-2, the F-117 and the F-22.

In 1990, with declining defense budgets and an easing of Cold War tensions, the cost of flights became prohibitive, and the SR-71 was mothballed. Blackbirds re-entered the Air Force active inventory in limited numbers in 1995 and resumed operations in January 1997.

Corona

National Reconnaissance Office photo

Corona was the first surveillance satellite system. From 1959 to 1972, 145 Corona flights sent back more than 800,000 images. Each image, on average, covered an area 10 miles wide by 120 miles long and could identify objects as small as 2 meters.

In the days before digital imaging, Corona could not reveal its images without returning them to Earth -- Corona's film capsule, drifting on a parachute, was snatched in mid-air by an Air Force C-119 airplane. Later advances allowed satellites to take their pictures digitally and beam them back to Earth, requiring no re-entry vehicle.

Information on Corona was declassified in 1995. Images shot by Corona are now held by the U.S. Geological Survey.

Minox camera

CIA photo

Developed by Walter Zapp in 1934, the Minox used special high-resolution 8x11mm film, which made it possible to build an extremely compact camera.

Well suited for close-range photography and easily concealable, the Minox was a favorite for photographing documents.

A measuring chain ensured the proper distance to the subject; the Minox viewfinder offers no feedback on focus.

Today, the Minox TLX is still offered, billed as "the camera for advanced 'hobby espionage'."

Microdots

Gathering intelligence is only a first step; for information to be useful, it must get back to headquarters undetected, past counterintelligence agents and wary border guards.

Microdots fit that mission to a T. A coded message could be shot to film, developed, and shot to film again, yielding an extremely small -- and concealable -- message.

Microdots can be made with specialized cameras like the one shown here, or even with an ordinary 35mm camera. To make a microdot, photograph a coded message with high-resolution film. Develop that film, mount the negative with a light behind it, and photograph it again. The resulting image, which can be cut from the second negative, is less than a quarter of an inch across.

Microdots were hidden in dental fillings, behind postage stamps and in narrow slits cut in the sides of postcards, delivered right under the noses of enemy counterintelligence. Once delivered, they could be read with a pocket microscope, or even with a viewer small enough that it could be hidden inside a cigarette.

Bugs

Simply put, a bug is a hidden microphone. It can be attached to a tape recorder via wire, or to a radio transmitter. Spies built smaller and smaller bugs, and found ever more creative ways of hiding them.

One of the most ingenious bugs ever developed was "The Thing," a listening device found in the Great Seal that hung on the wall of the U.S. Embassy in Moscow. The seal, a gift from the Soviets, had a tiny hole under the eagle's beak to allow sounds to reach the listening device.

Western experts were at first baffled; the Thing had no batteries, no power supply, and did not transmit radio signals, which made it extremely difficult to detect.

An expert from Britain's MI5 finally solved the puzzle; the Thing was hit with high-frequency radio waves from outside the embassy. Sound absorbed by the microphone caused the antenna to vibrate, causing modulations in radio waves beamed at it and reflected back to a receiver.

Invisible ink

Invisible ink allows messages to pass undetected in plain sight, making every innocuous-looking letter or postcard a possible means of sending secret messages.

A visible message is written in ordinary ink, with the invisible message written between the lines, or in the unused portion of the page.

The simplest invisible inks are organic compounds -- vinegar, lemon juice, or even urine -- that are invisible at room temperature but turn brown when heated.

The example pictured was created with a lemon wedge and a toothpick and was "developed" with an ordinary incandescent light bulb. More sophisticated inks can be read only when a second chemical is applied to the invisible ink, and others are visible only under ultraviolet light.

Bug detectors

If a bug is a hidden radio transmitter, a bug detector is just a specialized receiver. Bug detectors lock on to sources of radio waves, isolating them from background radiation and allowing a trained user to locate the source.

Once briefcase-sized devices, bug detectors have, like most electronic devices, gotten smaller. One commercially available bug detector, disguised as a common pager, vibrates when it detects suspicious transmissions.

Bug detectors can only operate when the bug is transmitting -- so later generations of bugs were remote-controlled, transmitting only when activated from outside. The cat-and-mouse game continued.

TEMPEST

In the course of creating images on a screen, cathode ray tubes -- the screens of computer monitors and televisions -- give off radio-frequency radiation.

TEMPEST systems can decode these radio signals, giving an enemy a clear picture of what's on any computer screen from hundreds of yards, or even as far as a kilometer, away.

Because it is passive, merely receiving signals, TEMPEST monitoring cannot be detected. Computers for sensitive use are specially equipped to minimize or scramble TEMPEST signals; the means of protecting computers remain classified.

Hidden still cameras

The venerable Minox camera is fine for photographing documents, but sometimes an agent may need to take photos completely undetected. For that reason, Cold War spymasters built cameras that looked like umbrellas, tie pins, matchboxes -- anything but cameras.

The camera shown is a KGB design. Strapped to the user's body with a harness around the chest, it took photos through a lens disguised as an ordinary tie pin. The spy would wear the tie pin all the time, so that it would not be conspicuous when the camera was in use. The controls for the camera, connected by a cable, fit easily in a pants pocket.

Hidden video cameras

Through the Cold War years, video cameras became steadily smaller. The pinhole camera shown is actual size, and can shoot through extremely small holes, like the ones in acoustic ceiling tiles found in many offices.

The cameras are can be connected to video tape recorders or transmitters; the camera and recorder can easily fit in a briefcase or handbag, and the camera with a transmitter can be concealed in a hat.

The camera pictured is now commercially available from several sources for a few hundred dollars, not including the transmitter. Similar cameras are used by some TV news organizations for "hidden camera" reports.

Hidden audio recorders

Tape recorders served two major functions -- allowing a spy to record conversations for later analysis, or allowing taping of a room when the spy wasn't in the room.

Early hidden recorders could be hidden in a briefcase -- an entire briefcase -- and stopped and started from a switch concealed in the handle.

In the 1970s, the KGB developed the Mezon recorder, shown here at half its actual size. The Mezon recorded to a spool of thin wire instead of tape, and could be carried in a pocket or worn in a harness under clothing. Remote control switches and hidden microphones (under a lapel, for example, to record conversations) made the Mezon a versatile tool.

Today, exotic devices like the Mezon have been made obsolete by microcassette recorders, commercially (and cheaply) available.

Fiberscope

Inspired by medical instruments, the fiberscope can look through walls (via a small hole), under doors and around corners.

The user looks through an eyepiece, along fiber-optic lines, through a wide-angle lens at the opposite end. Unlike hidden video cameras, it does not give itself away with radio signals or other electronic emissions

One-time pad

One of the oldest encryption methods, dating back to the 1920s, the one-time pad is also one of the most secure.

Two copies of the one-time pad are used -- one for the sender, and one for the receiver. Each contains a random string of letters, which are used to painstakingly encrypt each letter of the outgoing message, one at a time. The receiver of the message then uses the same key to decode the message, also one letter at a time.

One-time pads can only be used between one sender and one receiver, and is too cumbersome for all uses. It can also be cracked by painstaking trial and error, trying all of the millions of possible combinations.

The VENONA project at the U.S. National Security Agency cracked many supposedly secure Soviet messages, including some that employed one-time pads. The project lasted from 1943 to 1980, and some of its records were declassified in 1995.

Cray Supercomputer

The Cray-1, pictured, was the first Cray supercomputer, introduced in 1976. It could perform 100 million arithmetical operations per second, a breakthrough at the time; Cray's current systems can perform up to 2.4 trillion.

Fast computers have revolutionized code-breaking; in minutes, they can crack codes that would take days for a human, and can crack "unbreakable" codes in days or weeks.

Fast computers can perform what is called "blunt force" decoding -- cracking a code by trying every possible combination, which can easily run into the trillions.

Computers were not new to espionage -- one of the first electronic computers, the British Colossus, was built during World War II for the sole purpose of cracking German Enigma codes. Its existence remained secret until 1970.

The Cray-1 had several unique features. The high speed of its processors required a liquid nitrogen cooling system, and for the price ($700,000) the buyer chose the color of the upholstered bench.

Infrared telephone

This device, built for German intelligence services in the 1960s, allowed clandestine communications between two operatives as far as 1.86 miles (3km) apart.

Using infrared light, it could send signals day or night, but both units had to be pointed directly at each other. Rain and snow interfered with the signal.

Because it only worked by line of sight, the infrared phone is, even with modern technology, extremely difficult to detect or intercept.

Invisible ink

Invisible ink allows messages to pass undetected in plain sight, making every innocuous-looking letter or postcard a possible means of sending secret messages.

A visible message is written in ordinary ink, with the invisible message written between the lines, or in the unused portion of the page.

The simplest invisible inks are organic compounds -- vinegar, lemon juice, or even urine -- that are invisible at room temperature but turn brown when heated.

Dead-drop spike

A "dead drop," despite the ominous name, is simply an exchange of information without the two operatives meeting face to face.

The dead drop spike is a time-honored method of concealing information for later pickup. A simple metal cylinder, the spike is waterproof and mildew-proof, and can be quickly and unobtrusively pushed into the ground with the heel, or placed in a stream for later retrieval.

Hollow coin concealment

Hollow coins, carefully machined from two actual coins, blend into a pocketful of change and are easy to conceal. This example is made from a silver dollar, a rather large coin, giving it a relatively large capacity.

Hollow coins can be used to smuggle small written messages, microdots or film. In a similar concealment, U-2 pilot Francis Gary Powers carried a poison-tipped needle hidden in a silver dollar.

Dead-drop bolt

This bolt, part of a bridge in West Germany, was used as a dead drop by Soviet agents. The bolt was hollow, and the head could be removed, allowing tightly rolled notes or microfilm to be stashed inside. Once in place, it blended in perfectly with its surroundings.

Like many concealments, the head of the bolt was reverse-threaded; that is, it was loosened by turning clockwise, instead of the usual counterclockwise, thus offering a bit more security against accidental detection.

A similar ploy, using hollow nails as a dead drop, was used by the spy ring led by Rudolph Abel, who helped smuggle American atom bomb secrets to the Soviets.