Gentlemen do not read each other's mail.

Henry L. Stimson, secretary of state

INFORMATION HAS ALWAYS BEEN SOCIETY'S GREAT EQUALIZER. But the control of information is most important to the sovereign in the conduct of war. Advance knowledge of where the enemy is, in what strength, and with what intent has often changed the long odds of battle. The drive to obtain this information and the desire to keep it hidden form the history of cryptography.

Not surprisingly, it was the militant Spartans who established the first known system of military cryptography. David Kahn tells us:

As early as the fifth century B.C., they employed a device called the 'skytale,' the earliest apparatus used in cryptography and one of the few ever devised in the whole history of the science for transposition ciphers. The skytale consists of a staff of wood around which a strip of papyrus or leather or parchment is wrapped close-packed. The secret message is written on the parchment down the length of the staff; the parchment is then unwound and sent on its way. The disconnected

This enciphering device is mentioned by Thucydides in describing how the rulers of Sparta, ordered a too ambitious Spartan prince and general home in about 475 B.C. About a century later, according to Plutarch, another skytale message recalled the Spartan general "Lysander to face charges of insubordination. Xenophon also records the skytale's use in enciphering a list of names in an order sent to another Spartan commander."[83] 

It is a long way from these primitive efforts to conceal information from the enemy to modern codes and ciphers. Though the technology has changed dramatically, the intent has remained the same: to read the enemy's messages and to keep one's own secret. In addition to the effectiveness of the code, the way in which messages are carried or transmitted from one place to another is an important element in the security of the system.

So long as military dispatches were hand carried, the enemy had to capture the messenger to obtain the message. This presented problems not only for the enemy in obtaining intelligence but also the home commanders as well: Events often moved faster than the messengers. Martin van Creveld wrote about the Battle of Coronea, which took place in 394 B.C. and "where news of a defeat came right in the middle of a ceremony in which the Spartan King Agesilaus was being crowned victor by his men." The speed and safety of communication were not the only difficult problems faced by the sovereign. Sometimes the messenger got through safely but unknowingly delivered his message to the enemy. This fact was well understood by commanders and played a role in the American Revolution. Barbara Tuchman tells us:

On July 28, de Grasse wrote the conclusive letter that was to reach Rochambeau and Washington on August 14 informing them that he was coming with 25 or 26 ships, bringing three regiments, and would leave on August 3 for Chesapeake Bay. Speeding directly by the , the letter did not pass through diplomatic channels to be read and copied by agents in English pay...In the 18th century, the practice was customary. Foreign ministries maintained regular clerks, who, through long familiarity, learned the codes, and read and copied the correspondence of officials of foreign countries."[84] 

While de Grasse and Washington managed to keep secret the news of the movement of the French naval and military forces and thus contribute significantly to the success of the American Revolution, some years later it was not secrecy but simply the slowness of a sailing ship bringing a clear text message that caused many men to die. On January 8, 1815, Andrew Jackson's army defeated the British at the Battle of New Orleans, an engagement that was fought more than two weeks after the Treaty of Ghent ending the war was signed. It is difficult in this information age to understand a time when it took up to six weeks for news to cross the Atlantic, depending on the wind. In more recent times, I happened to be at a White House dinner in May 1975 when the Cambodian government seized the crew of the American cargo ship Mayaguez. The crew was rescued by the U.S. Navy and Marines, and I inquired of an admiral seated next to me after dinner how long priority messages took to travel from Thailand to the Pentagon and was told really urgent ones came through in six hours. Despite the message delays through military channels, it was possible for President Carter to have talked by telephone to the pilots of the helicopters in the aborted rescue attempt of American hostages in Iran.

Military commanders have from the beginning searched for faster and more secure ways to communicate with their troops. The first breakthrough came with the invention of the optical telegraph in 1794, which consisted of a series of towers, the signal flags or lights from one being visible to the next. This device greatly expanded a military commander's control over larger areas and speeded up the transmission of messages without greatly damaging security. It was this system of moving information that enabled Napoleon to maintain control over large areas of conquered territory. Today we have only the legacy of "telegraph hills" to remind us of what was once state-of-the-art information technology.

The invention and then the widespread use of the telegraph made military communications much faster and easier but also less secure than hand-carried messages. While wiretaps could produce some intelligence, they required agents behind enemy lines to attach the wires and then get the intercepted messages back to their own commanders. Radio finally gave military commanders what they had always sought -- continuous and fast communications to control an entire army. It also provided the first sure and rapid way to communicate with air and naval forces. Like most technology, however, radio was a two-edged sword. Anyone, friend or foe, can tune in if he or she knows the correct frequency and has the proper equipment. Radio communication came into common use by the military during World War I and spawned the invention of radio-direction finders to locate enemy stations. Intercepting enemy messages became relatively easy. Thousands of intercepts piled up, but since most of the messages were in code, they were of little use unless their secrets could be unlocked. Only the French were well prepared for this task with a tradition in cryptanalysis stretching back to the great Rossignol in the seventeenth century, were well prepared for this task. "One of the most important contributions of the Rossignols," writes David Kahn, "was to make crystal clear to the rulers of France the

Secretary of State Henry L. Stimson's dictum was discarded when war broke out, and black chambers were established on both sides of the battle lines in an effort to break the enemy codes and supply information to the military commanders. Indeed, this battle of the black chambers continues to this day. In World War II, the ability of American cryptologists to crack the Japanese code, and thus supply vital intelligence to our naval commanders in the battles of the Coral Sea and Midway is generally regarded as one of the most significant factors in turning the tide of battle.

The breaking of the Japanese diplomatic and naval codes was all the more remarkable when one considers that the United States entered World War II with very little in the way of truly sophisticated ciphers. The mainstay for army divisional traffic was a Swedish machine invented by Boris Caesar Wilhelm Hagelin and given the army designation of Converter M-209. It was a polyalphabetic system that produced a printed tape, and because of inner workings, more than a hundred million letters could be enciphered before the mechanical sequence in the machine would repeat itself. Since the cipher's secret could be broken down given time, efforts were expended to design a more secure system.

By the end of the war we were using an electromechanical device known as m-134-c, or SIGABA. This was a highly effective cipher machine. David Kahn writes:

The branch of the Army's Signal Security Agency charged with testing American cryptosystems had failed in all its efforts to break down messages enciphered in m-134-c. And, though the United States did not know it at the time, German cryptanalysts had, despite prolonged efforts, likewise found it impossible to read these cryptograms."[86] 

Because much of the traffic from Eisenhower's headquarters was on SIGABA ciphers, extraordinary security measures were taken to protect both the machine itself and the rotors that made it work. The machine was stored in one safe and the rotors in another. Just after war's end, I was the officer responsible for two SIGABA machines, sets of rotors, and accompanying manuals in a signal center in Cebu. It was a great feeling of relief when a newly minted second lieutenant showed up to sign for all this top-secret equipment and allowed me to go home unencumbered by the weight of that responsibility. And yet by today's standards, even this system was primitive.

As codes and code breaking have become more sophisticated, so also have the means of transmitting messages in wartime. These communication lines now stretch over huge distances. One recent example was the war over the Falkland Islands. The distance from Great Britain to the Falklands was almost eight thousand miles, and yet the British forces operating under strict rules of engagement were all directed from Northwood, England, the home of fleet headquarters. Contrast this with the fact that it took fifteen and a half hours from the time the United States intercepted and decoded the message to the Japanese ambassador to break off negotiations with the United States at 1:00 p.m. on December 7, 1941, until that warning was delivered to General Short in

Today modern information technology has the capacity to furnish some battle information in real time. Knowing precisely where one is on a battlefield or in the air over enemy territory gives ground commanders and pilots a competitive edge in battle. This information was especially important in the Gulf War, which was fought in a trackless desert devoid of the usual landmarks. Allied military commanders and pilots were able to pinpoint their position by use of hand-held radio receivers picking up signals from our Global Positioning Satellite System. Using this information, pilots could approach at high altitude beyond the range of antiaircraft fire, and only when the system indicated that they were directly over the assigned target did they dive down to drop their bombs. In addition to knowing precisely where you are, knowing when and where the enemy is launching missiles can turn the tide of battle. In Desert Storm, a twenty-year-old Defense Support Program (DSP) satellite using infrared detectors that sense the heat from missile plums reported ballistic missile launches in real time. These same satellites can also "see" nuclear explosions anywhere on the surface of the planet.

In addition to precise information about their exact location, commanders have always wanted a panoramic view of the battlefield but have not always welcomed the technology that might supply it. The first attempts to obtain a "view" of an entire battlefield were made by hot-air balloon enthusiasts in the late eighteenth century. These early pioneers of flight attempted to sell the military on the usefulness of aerial observation of enemy action, but even so great a general as Napoleon failed to appreciate its usefulness. Military men have often failed to embrace new military hardware ranging from the battle tank to the submarine, and aerial observation was no exception. Alan Palmer writes despite official discouragement, "Carnot encouraged the use of captive bal-

Modern commanders take a different view and now rely on many kinds of airborne reconnaissance. The American Armed Forces use the Airborne Warning & Control System (AWACS), which provides extended radar coverage beyond the line-of-sight, horizon-limited surface radar. Indeed, the AWACS (E3-C Sentry) which is based on the Boeing 707-320B Airframe, powered by 4 Pratt and Whitney TF 33 engines, when flying over France, gives the commander a view of almost the entire NATO (North Atlantic Treaty Organization) command area. The radar, which is built by Westinghouse, provides long-range surveillance by means of a large rotating radome attached to the top of the fuselage. This special radar, developed for the AWACS, has a "look down" capability which can "see" small, low-altitude targets in land and sea clutter.

Long-range surveillance is but one of the pieces of information which can be supplied by AWACS. The twenty-three-member crew, which includes thirteen tactical controllers as well as communication and countermeasure operators, has access to fourteen situation display consoles for airborne command and control.

Today the "look down" radar is being further enhanced by a major systems improvement program which is said to permit identification of cruise missiles and Stealth-type aircraft and even further ranges, approximately 290 nautical miles at 29,000 feet.[88] 

The navy has a similar need for information which is supplied by the carrier-based E-2 Hawkeye developed by Grumman Aircraft. The surveillance radar, built by GE, is capable of detecting airborne targets anywhere in a 3-million-cubic-mile surveillance volume while at the same time monitoring mar-

While these, and other aircraft with advanced pulse Doppler radar, track enemy targets with previously unheard of accuracy, the weapons are information systems in and of themselves. In at least one instance, it can be argued a "smart" weapon was an equalizer between an illiterate Afghan tribesman and the might of the invading Soviet army. The weapon is called the Stinger; its basic ground-to-air version uses an IR (infrared) homing sensor, can be carried by one man, and is fired from the shoulder. The Stinger is effective against low-flying helicopter gunships as well as fixed-wing aircraft. It is a so-called fire-and-forget missile and carries on board a sophisticated information system to identify friend from foe. The IFF (Identification, Friend, or Foe) system interrogates coded transponders on friendly aircraft. Recently there have been several upgrades of the basic Stinger, including POST (Passive Optical Seeker Technology) and reprogrammable microprocessor. The basic Stinger had a profound effect on the war in Afghanistan and also in Angola. Weighing 34.5 pounds, including the launcher, the missile uses a solid-fuel rocket motor. With an estimated effective range of two to three kilometers and a very high target interception rate, it was the nemesis of the Soviet attack helicopter in Afghanistan. For some time it was estimated that a Russian jet or helicopter was shot down each day with a Stinger. This devastating defense by the Mujahedin forced Russian aircraft to fly at higher altitudes, which hindered their effectiveness in ground support roles. It is probably not an exaggeration to say that not since the musket destroyed the once overpowering fire power of massed bowmen has new technology performed such an equalizing role.

In the air, the first known use of "smart" air-to-air missiles in combat occurred, Michael Fitzpatrick writes, in October 1958.

U.S. supplied Nationalist Chinese F-86's downed fourteen Chinese MIG-17's...in a single day. A quarter of a century later, during the 1982 Falkland War, British Harriers routed Argentina's faster, French-built Mirage fighters, with nineteen "kills" in twenty-three engagements...Also in 1982, during intense Israeli-Syrian fighting...Syria lost over fifty-five Soviet-built MIGs...The missile that performed so well in each of these instances was the AIM-9 Sidewinder.[89] 

Like its cousin, the Stinger, it relies on information technology for its effectiveness.

The equalizing effect of information technology was clearly evident in the seventy-four-day war between the world's third largest naval power, Great Britain, and a developing country, Argentina. The Ganleys summed up the situation this way:

Argentina, with no weapons industry of its own to speak of, could challenge the quite powerful Great Britain because it had stockpiled large quantities of modern weapons from various Western countries. It had a small navy of old, but updated American-, British-, and West German-built ships and submarines fitted with modern missiles and torpedoes. Because of British nuclear submarine power, Argentina's navy was neutralized in this conflict. But at least six of its ships had French Exocet surface-to-surface offensive missiles and British Sea Cat missiles for surface-to-air defenses which would have been usable if circumstances had been only a little different. Argentina's land-based Roland missiles, which protected the Stanley Airport runways, came from France, and its tanks and tank guns had been designed in West Germany.[90] 

With all the power of Great Britain, it still lost six ships during the war; it failed to find the larger Argentine submarines and

In October of 1988, a paper was presented by the U.S. government by the Commission on Integrated Long-Term Strategy, which was chaired by Dr. Fred Iklé and Prof. Albert J. Wohistetter, that stated that "smart conventional weapon systems are one of several classes of military technologies with the potential to profoundly influence future warfare."[92]  The report also stressed that "Nonmaterial factors -- tactics, training, leadership, morale -- are critically important."[93] 

With these caveats, smart weapons are then defined: "The term 'smart' applies to weapons that receive information during flight -- from on-board systems and/or external sources -- to help acquire and select targets."[94]  Anyway that "smart" is defined, what it means in practice is some kind of an on-board information system. As in all things, what man invents man can counteract. If the "brains" of smart weapons are software, we are vulnerable to relatively cheap attacks on some of our most costly and complex weapon systems in our arsenal.

Work done by Scott A. Boorman, a Yale University sociology professor, and Paul R. Levitt, a mathematician, suggests:

At a time when computer software is part of 80 percent of U.S. weapon systems now in development, software warfare -- attacking the software that controls or operates these weapons -- may be the most effective, cheapest and simplest way to cripple vital U.S. defenses. Software warfare in fact is coming of age as a new type of systematic offensive warfare, one that can be waged far removed in space and time from any battlefield to influence not only combat outcomes but also peacetime balances of power.[95] 

Recently, computer "viruses" have been in the news. These "viruses" are actually a string or strings of computer codes

"Software attack, often best carried out with the aid of well-placed insiders, is emerging as a coherent new type of systematic offensive warfare," according to Boorman and Levitt, writing recently in the military electronics journal .

It can strike key civilian targets, such as electronic funds transfer, other financial and data communications, air traffic control systems and even the vote-tallying machinery at the heart of the democratic process.

Tactics that can be used to disrupt computer operations include viruses, which clone themselves to spread to other computers; "Trojan horses," which look and act like normal programs but contain hidden commands; "logic bombs," which remain inactive until a certain result in computation; and "time bombs."

The so-called "logic bomb," which was planted in the computer software of the Los Angeles Department of Water and Power in the spring of 1985, made it impossible for that utility to access its own files for a week.[96] 

In today's world, wars can be won or lost in a week. If nothing happened when the president pressed the button, if all our communications froze and our radar failed to function, our defensive posture would change dramatically. It does not take much imagination -- while the story of the John Walker family is fresh in our minds -- to imagine that some software programmer might sell out to our adversaries and plant a few "logic bombs" to bring down our communications or disrupt our military guidance systems. When you compare the cost of software warfare with a new weapons system, it can only be described as incredibly cheap by any standards.

Unlike complex weapons systems, planting software time bombs or "viruses" is within the financial reach of the smallest countries and, if successful, is capable of altering military balance in a manner similar to the way the invention of new

The British found out in the Falklands war that their software controlling the Sea Wolf missile system on British warships could not cope with two aircraft attacking along parallel flight paths. Since the system could not decide which plane to shoot first, it simply shut down. This was not sabotage, but an oversight in the software design, and is illustrative of the huge military cost involved if the system does not function in combat.

There have been cases of intentional software warfare. Scott Boorman has written about a serious case of software sabotage uncovered in the 1970s at a U.S. Army supply base in Taegu, Korea. A group of South Koreans and U.S. personnel manipulated the inventory program "to siphon off many million dollars a year -- $18 million is one figure that has been indicated -- worth of military supplies," according to Mr. Boorman.[97] 

Another area of vulnerability can be in the computer chips themselves. Chips may be made that include listening devices. Often called Trojan horses, they can collect and manipulate data. Americans found this out the hard way in the construction of the American Embassy in Moscow. Indeed, the reported in June 1987 that James Schlesinger, a member of the team that was sent over by the secretary of state to inspect the embassy, stated that "some of the bugs found in concrete parts of the building...were so advanced that American experts remain baffled as to how they are supposed to work."

It is not necessary to plant bugs in the walls to access the information stored in thousands of military data bases. While student "hackers" delight in accessing electronic bulletin boards and attempting to break into various data bases as a kind of intellectual challenge, sometimes these efforts take on a more serious coloration. In 1985 a hacker -- who it turned

After tracking the hacker through thirty or forty computers, Stoll summed up his thoughts:

...our networks seem to have become the targets of (and channels for) international espionage. Come to think of it, what would I do if I were an intelligence agent? To collect secret information, I might train an agent to speak a foreign language, fly her to a distant country, supply her with bribe money, and worry that she might be caught or fed duplicitous information.

Or I could hire a dishonest computer programmer. Such a spy need never leave his home country. Not much risk of an internationally embarrassing incident. It's cheap, too -- a few small computers and some network connections. And the information returned is fresh -- straight from the target's word processing system.

Today there's only one country that's not reachable from your telephone: Albania. What does this mean for the future of espionage?[99] 

While agents in place are still seen as an indispensable element in obtaining good intelligence, that agent might well

With so many ways for information to be obtained; efforts have been made over the years to find a way to send a message, the very existence of which is concealed. This science has been given the name of steganography and includes everything from invisible ink to advanced electronic deception. One of the most effective ways to pass information is the microdot. This photographic process reduces the picture of a document to the size of a period on this page. The picture can then be placed unnoticed on innocent documents carried across borders and enlarged and read by the recipient. The same principle can be used electronically; messages are compressed and transmitted in a "burst" lasting a few seconds -- too short a time, it is hoped, for the sender to be located by a radio direction finder. A similar technique is used to dilute the strength of a radio signal so that it blends with and gets lost in background noise. There is an almost endless list of electronic methods of steganography. One way among many was a system of rapidly changing frequencies, or as it was called, frequency hopping. This system appeared in the early 1970s when "TRW began designing a satellite system for use by the CIA in communicating with agents in 'denied areas.'"[100]  Private designers of somewhat similar systems found that instead of the patent they had applied for, they received a secrecy order.

One day, Jack Scantlin, who designed the Citicard and the cash machines they operated, came into my office and asked what I was worried about that day. I told him that so much money was moving over the wire from London to New York, I was concerned that the circuit would be intercepted and the money diverted. The answer was obviously encryption, but most commercial devices were slow and not very secure. A few months later, my phone rang and a senior officer in the Department of Defense inquired whether I knew a Jack Scantlin. I told him I did, and he then said that Scantlin had

All of these efforts and many, many more are designed by the sovereign to protect the secrecy of information and move it from here to there safely and in a time frame when it is still useful. Equally huge efforts are made to break the ciphers and code, intercept the messages, and get the information so revealed to policymakers or fighter pilots in time to be useful. This battle of technology was christened the "Wizard War" by Winston Churchill and assigned a crucial role in the Battle of Britain. The secrets of science ranged from Britain's suc-

Yet if we had not mastered its profound meaning and used its mysteries even while we saw them only in a glimpse, all the efforts, all the prowess of the fighting airmen, all the bravery and sacrifices of the people, would have been in vain. Unless British science had proved superior to German and unless its strange sinister resources had been effectively brought to bear on the struggle for survival, we might well have been defeated, and, being defeated, destroyed.[101] 

In that great war, once again information was the great equalizer.

[83] David Kahn, The Code Breakers (New York: Macmillan, 1967), p. 82.

[84] Barbara Tuchman, The First Salute (New York: Ballantine, 1988), p. 232.

[85] David Kahn, The Code Breakers, p. 162.

[86] Ibid., p. 510.

[87] Alan Palmer, An Encyclopedia of Napoleon's Europe (New York: St. Martin's Press, 1984), p. 23.

[88] Aviation Week & Space Technology, 31 July 1989, pp. 55-67.

[89] Michael Fitzpatrick, "A Case Study in Weapons Acquisition: The Sidewinder Air to Air Missile," Journal of International Affairs, Summer 1985, p. 175.

[90] Gladys D. and Oswald H. Ganley, To Inform or to Control? (Norwood, N.J.: Ablex Publishing Co., 1989), p. 231.

[91] Ibid., p. 234.

[92] A Paper by the Standoff Weapons Panel, Offense-Defense Working Group, submitted to the Commission on Integrated Long-Term Strategy, October 1988, p. 1.

[93] Ibid., p. 2.

[94] Ibid.

[95] Scott A. Boorman and Paul R. Levitt, "Deadly Bugs," Sunday (Chicago Tribune Magazine), 3 May 1987, section 10.

[96] Scott Boorman and Paul Levitt, "Software Warfare and Algorithm Sabotage," Signal, May 1988.

[97] Ibid.

[98] For the full story, see Clifford Stoll, The Cuckoo's Egg (New York: Doubleday, 1989).

[99] Ibid., p. 303.

[100] James Bamford, The Puzzle Palace (New York: Penguin Books, 1983), p. 448.

[101] Winston S. Churchill, "The Wizard War," chap. 4 in Their Finest Hour (Boston: Houghton Mifflin, 1949), p. 381.