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National Cryptologic Museum - Exhibit Information

18th Century Cipher Device Exhibit

African-American Experience Exhibit

Biometrics Exhibit

American Civil War Exhibit

American Civil War: U.S. Army Signal Flag Exhibit

American Civil War: Union Code Book & Confederate Cipher Cylinder Exhibit

American Revolutionary War: Revolutionary Secrets

Cold War: Aerial Reconnaissance Exhibit

Cold War: GRAB II Elint Satellite Exhibit

Cold War: Great Seal Exhibit

Cold War: U-2 Incident Exhibit

Cold War: U.S.S. Liberty Exhibit

Cold War: U.S.S. Pueblo Exhibit

Cold War: VENONA Exhibit

Computer Development: Cray Supercomputers

Computer Development: Harvest Tape Drive

Computer Development: RISSMAN

Computer Development: Special Processing Lab

Computer Development: StorageTek

NSA/CSS Cryptologic Memorial Exhibit

NSA 60th Anniversary - 60 Years of Cryptologic Excellence

60 Years of Cryptologic Excellence: 1950s

60 Years of Cryptologic Excellence: 1960s

60 Years of Cryptologic Excellence: 1970s

60 Years of Cryptologic Excellence: 1980s-1990s

60 Years of Cryptologic Excellence: 2000-Present

Friedman, Safford and Washington Exhibit

Hall of Honor Exhibit

Looking for a Sign: Hobo Communication in the Depression

Hobo Communications: A Brief History of Hobos and Their Signs

Information Assurance Exhibit

The Kahn Collection

Korean War Exhibit

Language Exhibit

The Magic of Purple Exhibit

Museum Library

Postal Metering Exhibit

Rare Book Collection Exhibit

September 11th Memorial Exhibit

Vietnam War Exhibit

Women in American Cryptology Exhibit

World War 1: American Black Chamber Exhibit

World War 1: Radio Intercept Site Exhibit

World War 1: Zimmermann Telegram Exhibit

World War 2: Battle of Midway Exhibit

World War 2: 'Big' Machines Exhibit

World War 2: Code Talkers Exhibit

World War 2: Enigma Exhibit

World War 2: SIGSALY Exhibit

World War 2: U.S. Navy Cryptanalytic Bombe Exhibit


18th Century Cipher Device Exhibit

Photograph of 18th Century Cipher Device ExhibitThe National Cyptologic Museum acquired this cipher device from a West Virginian antique dealer, who found it in a home near Monticello. Thomas Jefferson described a similar device for the English language in his writings, and it is sometimes referred to as the "Jefferson Cipher Wheel." However, the connection to Thomas Jefferson remains unproven. Jefferson's design was probably based upon an unnamed earlier device. Similar systems have been described by writers, including Francis Bacon in 1605, and may have been common among early European cipher bureaus known as "Black Chambers."

The device uses scrambled alphabets on the edges of each wheel to cipher a message. By aligning the plain text letters in one row, any other row can be selected as the cipher text. The wheels are individually numbered and can be placed on the spindle in any prearranged order. The recipient of the cipher message arranges identical wheels in the same order, aligns the cipher letters in a row, and is able to read the plain text.

This particular artifact is thought to be the oldest extant true cipher device in the world. It was apparently for use with the French language, the world's diplomatic language used through World War I.

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African-American Experience Exhibit

Photograph of African-American Experience ExhibitThe experience of African-Americans at NSA and its predecessor organization mirrors the African-American experience in the United States and the federal government in the latter half of the twentieth century.

The first African-American hired by the Army Security Agency, and who later made the transition to the Armed Forces Security Agency, worked first in a segregated office. Senior supervisors were white and, many of the duties were menieal ones not wanted by whites.

In the 1950s, African-Americans began to move into the mainstream workforce. The segregated office was abolished and more African-Americans received supervisory positions.

Many African-Americans advanced to NSA's senior ranks. Many of those who began their careers in the segregated work environment finished at the top of their profession.

For many years it was believed that African-Americans had first been hired to work in cryptology only after World War II. Recent research has revealed, however, that the first large-scale hiring program for African-Americans began in 1944. By the end of the war, a segregated office of thirty African-Americans was engaged in researching messages encrypted in unknown systems, analyzing them, and producing translations.

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Biometrics Exhibit

Photograph of Biometrics ExhibitThe information age has revolutionized the way transactions are completed. The growth in electronic transactions has resulted in a greater demand for fast and accurate user identification. Passwords and Personal Identification Numbers can be shared, forgotten, lost, or stolen. Biometric technology is a way to achieve fast, user-friendly, authentication without requiring a separate card, key, or other physical device. It does, however, require a person be physically present to be verified.

Biometrics uses automated methods of recognizing a person based on physiological or behavioral characteristics. Fingerprint identification is the oldest system used for biometric technology. No one, not even identical twins, have the same fingerprints. A user's fingerprint can be scanned into a computer biometric system and retained for comparison. Any time access is requested, the fingerprint must be matched. The process is fast, non-invasive, and accurate. Other common human traits used for recognition are speech, face, hands, and eyes, and behavioral characteristics include handwriting and keystroke recognition. To increase authentication accuracy, different biometrics can be combined requiring not only a user's voice to match, but also his hand geometry, for example.

Biometrics is applicable to a wide variety of institutions. The criminal justice system, as well as customs departments at international airports have used it. There are many examples of biometrics for military and government use. One is to provide strong authentication for access to computer systems containing sensitive information. For this reason, the National Security Agency plays a role in the research of biometric technology.

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American Civil War Exhibit

Photograph of American Civil War ExhibitDuring America's first century, secret writing - cryptography - figured in many instances in which lives and fortunes were at stake and confidentiality was desired. Until nearly the middle of the 19th century, large armies moved over an extensive battlefield unassisted by any special technology to aid long distance communications or even tactical communications. By the same token, there was no reliable way for one side to obtain a steady source of enemy message traffic for intelligence purposes; collection was dependent on the capture of enemy transports or the deliberate apprehending of an enemy courier.

A partial answer came in 1844, when Samuel F. B. Morse successfully tested his improved electromagnetic telegraph between Washington and Baltimore. At the time of the American Civil War, both sides began encrypting high-level messages to be transmitted on the telegraph. More importantly, for the first time it became possible to collect such messages from the enemy in volume and in near real-time. Further, both sides established cipher bureaus in their respective capitals to work on enemy encrypted messages, one of the early examples of a centralized intelligence activity in the United States.

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American Civil War: U.S. Army Signal Flag Exhibit

Photograph of American Civil War: U.S. Army Signal Flag ExhibitIn the late 1850s, Albert J. Myer, an Army doctor, invented a method of communication using line-of-sight signal flags. Employed widely during the Civil War, the Myer flag system became the origin of the Army Signal Corps, and replicas of his flags emblazon the Signal Corps insignia even today.

Using various positions of the flag to represent letters of the alphabet, soldiers would wave them to send messages to other units. Both Union and Confederate soldiers became proficient in the Myers' system, known as wigwag. These specially selected soldiers had to be in an elevated location to be seen, so if a hill wasn't available, a tower was constructed. Some of these towers remain in existence today and are a reminder of this primitive code system.

Since the system is visual, the enemy, be it Union or Confederate, began intercepting the other side's messages. This forced the armies to begin encrypting. Also, due to the nature of this visual system, the signal officers, alone on top of a tower or hill with no weapon, risked their lives to send messages. Despite being somewhat removed from the front line, they were still within range, and easily within sight, of the enemy's fire.

The first use of wigwag during battle was by the Confederates at the Battle of First Manassas (or First Bull Run for the Union.) Captain Edward Porter Alexander, who worked with Myer in developing the system, caught the glint of bayonets from his viewpoint atop a hill and immediately wigwagged the message "Look out for your left; you are turned." It played an important role in the Confederate's victory.

This star flag, displayed in the Museum, is a rare item. In order to enhance morale, a signal flag was modified by placing a star in the center. This special flag was awarded only to Signal Corps officers who distinguished themselves in combat. The points of the star could be used to denote important battles in which the unit had distinguished itself. This flag is only one of two known to exist today in which all five points have been adorned with battles.

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American Civil War: Union Code Book & Confederate Cipher Cylinder Exhibit

Photograph of American Civil War: Union Code Book & Confederate Cipher Cylinder ExhibitNo matter how a message was transmitted, wigwag, telegraph, or written, for security purposes, it was often encoded or enciphered. A code changes a word or phrase into a different word, phrase, or number group; a cipher substitutes each individual letter for a different letter, number, or symbol. Below are two examples of such systems.

Although entitled Cipher for Telegraphic Correspondence, this book is actually a code book. It was used by Union General Joseph Hooker's code clerk and is one of the few books whose provenance is known. Important names, places, and military terms have two different code names.

The Confederate cipher cylinder is one of only two surviving cipher cylinders. Using a Vigenere square, plain text letters and their corresponding cipher letters are indicated by the position of the pointers. Each system has its benefits and disadvantages, but both offered an excellent level of security.

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American Revolutionary War: Revolutionary Secrets

Photograph of American Revolutionary War: Revolutionary Secrets Exhibit America’s independence, hard fought, was achieved with the help of codes, ciphers, invisible ink, visual communications, and hidden messages. These techniques, practiced by both the Colonists and the British, protected communications vital to the commanders. They disguised information needed to plan strategy, report the enemy’s capabilities, and provide warnings. Solving and reading the enemy’s secret messages also proved critical. Not only did it reveal the enemy’s intentions, but a few even revealed American traitors.


In August 1775, George Washington learned of a cipher letter addressed to a British officer and written by the Chief Physician for the Continental Army, Dr. Benjamin Church. Although Church claimed it was an innocent letter, he refused to decipher it. The simple substitution cipher Church used was easily solved for Washington. It revealed that Church provided details to the British of the Continental Army’s capabilities. Dr. Church was jailed for treason and eventually exiled to the West Indies, though his ship sank before arriving.

Benedict Arnold also proved to be a traitor to Washington and the United States. He was in communication with the British and used several different cryptologic methods to inform the British of American intentions. His proposed sale of West Point, a strategic military stronghold, was written using a dictionary code. His message was not intercepted, but his British contact was captured carrying details of West Point fortifications. He confessed and proved Arnold to be a traitor. Arnold escaped and served the British for the remainder of the war.

Washington had his own spies including a network in New York known as the Culper Spy Ring. They, too, used codes, but also employed invisible ink to send information. One of these messages involved the British actions of July 1780. Using invisible ink, Culper Jr. told Washington that the British were sending 8,000 troops to Newport, RI, to stop the arrival of the French fleet. Knowing this, Washington planned a ruse. He deceived the British into thinking he would attack New York City while the British were away and gain the town for the Continentals. The British returned to protect the city which allowed the French to arrive safely in Newport.

The British, too, were adept at the use of cryptologic methods. They also practiced steganography, the art of hiding messages. They hid notes inside ordinary objects such as double-sided canteens and hollow quill feathers. A message from Gen. Henry Clinton to Gen. John Burgoyne was cleverly disguised within another message. The full text appeared to speak well of on-going British actions, but when covered with a mask, the true messages spoke poorly of the situation prior to the Battle of Saratoga.

Another British general, Sir Charles Cornwallis, made use of cipher to encrypt his messages from Yorktown, VA. He pleaded with Gen. Clinton for reinforcements as the Continental Army gathered outside his fortifications. Some of his messages were intercepted and solved by James Lovell in the Continental Congress. The information was sent to Gen. Washington and aided in his plans to take Yorktown. Washington’s success along the York River proved to be the beginning of the end for British rule in the United States.

Although the war was not won or lost based on any one message, the secret communications of the Revolution played a role in changing the world.

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Cold War: Aerial Reconnaissance Exhibit

Photograph of Cold War: Aerial Reconnaissance ExhibitActive-duty and former military service members have sought to honor the sacrifices of aerial reconnaissance crews for some time. With changes in world politics and national security concerns, it became possible to declassify the existence of the program. This declassification provided the opportunity to recognize publicly the sacrifices made by servicemen performing aerial reconnaissance missions. Of the more than 150 cryptologists who have sacrificed their lives, 64 were involved in aerial reconnaissance missions. The museum displays two exhibits paying special tribute to the individuals who risked everything and the aerial reconnaissance mission that played a crucial role in the Cold War.

USAF C-130

On September 2, 1958, Soviet MiG-17 pilots shot down a U.S. Air Force reconnaissance aircraft. While conducting its mission, a USAF C-130 strayed into restricted airspace over Soviet Armenia. It was supposed to fly a "race track" pattern between the Turkish cities of Trabzon and Van essentially parallel to the Armenian border. It is unclear why the C-130 crossed into Armenian space. It is possible that the aircraft became confused between the navigational beacons in Turkey and those on similar frequencies in Armenia and Soviet Georgia.

The Soviets denied shooting down the aircraft, claiming the plane "fell" into their territory. At the time, they returned six bodies of service personnel. Seventeen men had been on board. Hoping the Soviets would have more information concerning the other 11 servicemen, the United States released tape recordings of the Soviet fighter pilots' communications during the shootdown, which clearly indicated the pilots took offensive action against the C-130. Despite the release of this information, the Soviets continued to deny involvement. It was not until the end of the Cold War that they released previously classified documents indicating that all 17 U.S. personnel had died in the crash.

An Air Force C-130 was refurbished and painted to match the markings of the down aircraft, #60528. It was flown to Fort Meade and dedicated at the National Vigilance Park on September 2, 1997.

U.S. Army RU-8D

The National Cryptologic Museum displays a mock-up of the interior of a small, reconfigured Army aircraft, the RU-8D. The RU-8D itself is on exhibit at National Vigilance Park. The plane was one of many different types of aircraft used by the Army to conduct its reconnaissance missions. Most of the missions were in support of tactical operations conducting short- and medium-range direction finding and signals intelligence. Early converted aircraft were slow, low-flying, and hot. The RU-8D significantly advanced the electronic collection mission with its onboard navigation system and improved antennas.

Following WWII, the Army "hitch-hiked" aboard Navy aircraft, but in the 1960s decided to expand its aerial reconnaissance program. The decision may have been due in part to the death of SPC4 James Davis in 1961. SPC Davis had been conducting a direction-finding (DF) mission from a jeep with a short-range DF system. While doing this ground direction finding, he was ambushed by the North Vietnamese. By March 1962, the Army had its first airborne DF platform, a small aircraft referred to by the soldiers as "teeny weenie airlines." However, over the decade, the Army's airborne collection systems improved and provided valuable information to military commanders.

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Cold War: GRAB II Elint Satellite Exhibit

Photograph of Cold War: GRAB II Elint Satellite ExhibitThe GRAB II (Galactic Radiation And Background) satellite and the Poppy satellite models, on loan from the Naval Research Lab (NRL) depict two of the earliest signals intelligence satellites to be launched by the U.S. Government. The first GRAB satellite was launched on 22 June 1960 following the loss in May of the U-2 spy plane flown by Gary Powers. The successful launch of the GRAB II satellite occurred on 29 June 1961.

The GRAB satellites had a dual mission. The unclassified mission, from which the satellite earned its name, was to gather solar radiation data. The secret mission involved the signals intelligence package carried aboard the satellite. It gathered radar pulses within a specific bandwidth from Soviet equipment.

The data was then downloaded to ground stations, recorded on magnetic tape, and couriered to the NRL, whose engineers had designed and built GRAB. Following initial analysis, the tapes were duplicated and sent to Strategic Air Command and the National Security Agency (NSA). Based on the information NSA received, analysts determined that the Soviets had radars that supported the capability to destroy ballistic missiles.

In 1962, the new National Reconnaissance Office (NRO) took over NRL's Electronic Intelligence (ELINT) satellite activities, and on 13 December 1962 launched Poppy 1. NRO launched six more Poppy satellites into orbit throughout the 1960s and into the 1970s. The satellites grew in size from a modest 20x24 inches and 55 pounds to 27x34 inches and 282 pounds.

Like GRAB, Poppy transponded ELINT data to ground stations. Operators and cryptologic technicians from the military services recorded information and signals of interest and reported them to NSA. NSA in turn analyzed the information and produced reports for the Intelligence Community.

The GRAB and Poppy programs dramatically increased the capability of the U.S. Intelligence Community to acquire ELINT data deep within the Soviet Union and supported a wide range of intelligence capabilities.

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Cold War: Great Seal Exhibit

Photograph of Cold War: Great Seal ExhibitOn August 4, 1945, Soviet school children gave a carving of the Great Seal of the United States to U.S. Ambassador Averell Harriman. It hung in the ambassador's Moscow residential office until 1952 when the State Department discovered that it was 'bugged.'

The microphone hidden inside was passive and only activated when the Soviets wanted it to be. They shot radio waves from a van parked outside into the ambassador's office and could then detect the changes of the microphone's diaphragm inside the resonant cavity. When Soviets turned off the radio waves it was virtually impossible to detect the hidden 'bug.' The Soviets were able to eavesdrop on the U.S. ambassador's conversations for six years.

The replica on display in the museum was molded from the original after it came to NSA for testing. The exhibit can be opened to reveal a copy of the microphone and the resonant cavity inside.

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Cold War: U-2 Incident Exhibit

Photograph of Cold War: U-2 Incident ExhibitOn May 1, 1960, while flying a CIA reconnaissance mission in a U-2 reconnaissance aircraft, Gary Powers was shot down over the Soviet Union. Although he parachuted to safety, Powers and his plane wreckage were captured. Soviet Premier Nikita Khrushchev accused the United States of spying. The international turmoil resulted in the cancellation of a summit meeting scheduled between President Eisenhower and the premier.

The incident only increased the tension between the two countries at the height of the Cold War. Following the accusations of spying, U.N. Ambassador Henry Cabot Lodge revealed the fact that the Soviets had been spying on the U.S. ambassadors in Moscow since 1945 using a microphone hidden inside a copy of the Great Seal of the United States. After its discovery in 1952, the CIA and National Security Agency examined the Great Seal and found that it was a very effective listening device.

The National Cryptologic Museum has the only piece of Gary Powers' aircraft on display in the United States. It was given to the museum by the Armed Forces Museum in Moscow where the plane's wreckage is exhibited.

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Cold War: U.S.S. Liberty Exhibit

Photograph of Cold War: U.S.S. Liberty ExhibitOn June 8, 1967, the U.S.S. Liberty, a U.S. Naval Ship, found itself in the middle of the 1967 Arab-Israeli Six-Day War. Cruising 25 miles off the Gaza coast, it was attacked by Israeli fighters and torpedo boats at 2 o'clock on a clear and sunny afternoon. There was no apparent provocation, and the reason for the attack has never been fully resolved, although Israel described it as an identification error and sent restitution for the damage and loss of life.

The U.S. government accepted the explanation of the Israeli government concerning the identification error. The loss of 34 men was the largest loss of life in a single event in American cryptologic history. It occurred, ironically, during a war in which the United States was not a participant.

The museum displays the flag that flew at the time of the attack. It was taken down and replaced by the ship's holiday flag, a larger, more visible, symbol. Also on display is a plaque listing the names of those lost on the Liberty. It stands as a reminder to visitors that those who produce intelligence on behalf of their country are frequently asked to risk or give their lives for their country.

On 2 July 2003, the National Security Agency released 'additional information relative to the 8 June 1967 attack on the U.S.S. Liberty. This release includes three audio recordings, transcripts (in English), three follow-up reports, and a U.S. Cryptologic History Report entitled "Attack on a SIGINT Collector, the U.S.S. Liberty."

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Cold War: U.S.S. Pueblo Exhibit

Photograph of Cold War: U.S.S. Pueblo ExhibitFollowing WWII, the peninsula of Korea was divided in two. The Soviet Union allied with the northern half, and the United States aligned with the southern half. For three years, 1950-1953, a war between the two Koreas raged, but ended inconclusively. The United States continued to support South Korea and garrisoned troops within the country. In the mid-1960s, following a period of relative peace, North Korea began aggressive activities toward the Republic of Korea.

In an effort to gather intelligence about North Korea's intentions, the U.S. Navy began operational cruises with AGER ships outfitted with reconnaissance equipment. In 1967, the U.S.S. Banner, while in the Sea of Japan, had been harassed by Soviet and North Korean navies, but no attempts were made to stop its mission. In January 1968, the U.S.S. Pueblo began a similar mission following the same track as the Banner through the Sea of Japan.

On January 23, 1968, while in international waters off the Korean coast, the North Koreans attacked the Pueblo. One man was killed while destroying cryptologic materials and three men were wounded. The attack was swift, and the North Koreans boarded the ship, capturing it, the crew, and the materiel the crew had been unable to destroy.

The 82 crewmen were held for eleven months before being released. The capture of the ship, which remains in North Korea to this day, constituted the largest single loss of such sensitive material. It compromised a wide range of cryptologic and classified documents and equipment.

The loss of the Pueblo, only six months after the attack on the U.S.S. Liberty, led to the end of this ship borne reconnaissance program.

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Cold War: VENONA Exhibit

Photograph of Cold War: VENONA ExhibitIn February 1943, the U.S. Army's Signal Intelligence Service, a forerunner of the National Security Agency, began a small, very secret program, which was eventually codenamed VENONA. The object of the VENONA program was to examine, and possibly exploit, encrypted Soviet diplomatic communications. Analysis of the messages revealed that some of the messages were from KGB and GRU operatives working undercover in the United States.

In the summer of 1946, linguists began to read portions of the decrypted messages. Over the next several months, analysts uncovered references to the Manhattan Project and other espionage activities in the intercepted messages. U.S. Army Intelligence, G-2, became very alarmed at the content of the messages that were being decrypted and contacted the Federal Bureau of Investigation about the messages. The FBI used this information to develop leads that led to some arrests and convictions for espionage against the United States.

Eventually more than 2,000 messages were decrypted at least in part and showed the detail of KGB tradecraft, espionage against the U.S. Atomic Program, the large number of people (about 200) claimed as intelligence assets, and the activities of the American Communist Party among other things.

The National Security Agency has now released declassified copies of the VENONA messages. All of the released documents are available for review at the 'Museum Library' and some significant messages are part of museum displays.

VENONA and the Rosenbergs

This display includes photographs of some of the American citizens who gave information to the Soviet KGB, replicas of the messages revealing the espionage, and some World War II-era artifacts similar to those used by KGB officers.

The Rosenbergs became a controversial case, due in part to the accusation and conviction of Ethel Rosenberg. VENONA messages indicate that her husband, Julius, was heavily involved in providing information to his KGB handler. At least one message shows that Ethel may have known about her husband's activities. Ethel's brother, David Greenglass, was also involved, selling details about the atomic bomb project in Los Alamos where he worked. It was David's testimony against his sister and brother-in-law that led to the conviction of the Rosenbergs for conspiracy to commit espionage.

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Computer Development: Cray Supercomputers

Photograph of Computer Development: Cray SupercomputersWorking with companies, such as Cray Research Inc., NSA has been a leader in computer development throughout its history. Some of the earliest supercomputers were designed and built for the National Security Agency.

On exhibit in the museum are two Cray supercomputers. The XMP-24 on display is the upgrade to the original XMP-22 that was the first supercomputer Cray ever delivered to a customer site. It was in operation from 1983 to 1993 and was arguably the most powerful computer in the world when it was delivered. It used serial processing to conduct 420 million operations per second.

The second generation Cray, the YMP, replaced the older version in 1993. It had a 32 gigabyte (32 billion bytes) memory capacity. In 1993 most personal computers held only 16 million bytes. The YMP used vector processing, a very powerful form of overlapping, parallel processing to conduct 2.67 billion operations per second. The YMP was decommissioned and went on display at the museum in 2000.

NSA, with its partners in industry, continues to be a leader in research and development of computer technologies, pioneering the frontiers of computer science and engineering. To house and develop these new systems, NSA has the world's largest supercomputing facility and the Special Processing Lab located on its campus.

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Computer Development: Harvest Tape Drive

Photograph of Computer Development: Harvest Tape DriveThe extraordinary versatility and efficiency of electronic computers have made them useful in handling almost every class of data. With the earliest design work on computers in 1946 came the realization of the potential usefulness of such machines for Agency purposes. NSA's computer installation ranks among the largest in the country.

NSA has been a silent partner with private industry from the earliest days of postwar computer development. Many commercial computer lines have sprouted from earlier designs for NSA use. A good example of this partnership was a cooperative project in the 1950s between NSA and IBM. The result of this collaboration, HARVEST, went on line in 1962 and was finally retired in 1976. IBM built a new, state-of-the-art second-generation general-purpose processor. To be successful, HARVEST had to have a super high-speed memory and high-speed tape drives, beyond anything then in existence. Developed over a five-year period, the most innovative component was TRACTOR, the high-speed tape drive system. It was the first fully automated storage and retrieval system and a precursor to some of today's storage systems, such as StorageTek.

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Computer Development: RISSMAN

Photograph of Computer Development: RISSMANRISSMAN was a telemetry processing system, built in the early 1980s featuring custom-designed hardware. As part of NSA's SIGINT mission, telemetry signals were collected by various platforms. Magnetic tape recordings of the intercepted signals were then sent to NSA's National Telemetry Processing Center for processing. These measurements were then sent on computer tape to various analysis centers which identified the function of the various transducers and developed performance estimates. This data was used to formulate defense policy and guide treaty negotiations.

TELLMAN, the Agency's first telemetry processor to make extensive use of a general purpose computer, became operational in 1969. In the early 1980's, TELLMAN was replaced with RISSMAN, which processed a wider variety of signals, with higher system reliability and lower maintenance costs. RISSMAN's custom-designed hardware (still required for the front-end of the signal path) is shown in this exhibit. RISSMAN used three Intel 8086 microcomputers to perform real-time process control, while Digital VAX-11 computers provided data demultiplexing, data file storage, user-interface, Local Area Network access, digital tape generation, and quality-control plotting services. RISSMAN was in daily use, often processing tapes around the clock, from the date of its delivery through the end of the Cold War.

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Computer Development: Special Processing Lab

Photograph of Computer Development: Special Processing LabNSA has exacting requirements for special computer chips. Because of the difficulty of satisfying its needs on the commercial market, and because of the highly classified nature of some of the chips, NSA opened a facility in 1991 to fabricate otherwise unobtainable devices. Applications Specific Integrated Circuits (ASIC) are produced in the Class 10 clean room within this facility. Microchips are manufactured, not only for NSA's supercomputers, but also for systems throughout the Department of Defense and the Intelligence Community.

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Computer Development: StorageTek

Photograph of Computer Development: StorageTekThe Storage Technology Corporation produces some of NSA's recording media storage libraries. This machine is an example of an automated tape cartridge system. It was designed for large, complex, high-performance environments, such as NSA's. It has the capacity for 6,000 tape cartridges each holding 50 gigabytes of data: a total of 300 terabytes. (300 terabytes would fill enough 8.5x11 paper to circle the globe more than 3,000 times!) Using a robotic arm, this StorageTek machine is capable of exchanging 175 cartridges per hour.

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NSA/CSS Cryptologic Memorial Exhibit

Photograph of NSA/CSS Cryptologic Memorial ExhibitThe National Security Agency/Central Security Service Cryptologic Memorial exhibit is a replica of the black granite wall found in the NSA Headquarters building at Ft. Meade, MD. It is intended to honor and remember those who have given their lives, "serving in silence," in the line of duty since the end of World War II. The Memorial was built in 1995 and lists the names of those cryptologists, both military and civilian, who have made the ultimate sacrifice. It is hoped that this memorial will serve as an important reminder of the crucial role that cryptology plays in keeping the United States secure and the role these individuals had in shaping the history of this country.

The Memorial Wall was designed by an NSA employee and is 12 feet wide and eight feet high, centered with a triangle. The words "They Served in Silence," etched into the polished stone at the cap of the triangle, recognize that cryptologic service has always been a silent service - secretive by its very nature. Below these words, the NSA seal and the names of 153 military and civilian cryptologists who have given their lives in service to their country are engraved in the granite. The names are at the base of the triangle because these cryptologists and their ideals - dedication to mission, dedication to workmate, and dedication to country - form the foundation for cryptologic service.

In honor of Memorial Day 2000, the Agency decided to commemorate the sacrifices and courage of these individuals in a special way. From the wall, two names were chosen and their stories were told. Although the focus shifted to only those two, it brought a sense of reality and seriousness to our rich heritage, and it reiterated the importance of the work being done at the Agency. Every year, new names are selected, and new stories shared.

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NSA 60th Anniversary - 60 Years of Cryptologic Excellence

Photograph of NSA 60th Anniversary ExhibitIn 1952, prompted by concerns regarding the United States' cryptologic capabilities, President Truman signed the National Security Agency into existence. This act consolidated all U.S. military and civilian cryptologic efforts under one roof bringing together the country's greatest technological minds. From its inception, technology has played a crucial role in supporting the U.S. armed forces and defeating our nation's adversaries. The men and women, civilian and military, who have contributed to this mission have not only influenced historic events, but have made technological advancements that have changed the world.

Part of the Agency's 60th Anniversary Celebration was the installation of the "60 Years of Cryptologic Excellence" exhibit at the National Cryptologic Museum. The items included in this exhibit represent a snapshot of the technological achievements of each decade and demonstrate how these devices supported our Nation in times of war and crisis.

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60 Years of Cryptologic Excellence: 1950s

In June 1950, the North Korean army marched across the 38th parallel into South Korea. This action caught the United States defense and intelligence organizations by surprise. In response to the crisis, National Security Agency cipher systems began utilizing transistors, printed circuit boards, and IBM key card technologies. During this time NSA also realized the need to continue the advancement of computer technologies. From its earliest days, the Agency partnered with private industry to produce a wide range of computer related technologies.

Featured here are examples of NSA's early efforts employing cutting-edge technology to achieve its mission.

Computer Circuit Board

Photograph of Cryptologic Treasures: Circuit BoardThis circuit board is thought to have been part of ABNER, the first NSA-designed in-house digital computer. Delivered in 1951, it had a memory of 1024 48-bit words and used two-foot long mercury tubes to convert electric signals to analog. As new developments in the industry occurred, engineers altered ABNER's design during construction to accommodate the latest technology.

Computer Punch Cards

Photograph of Cryptologic Treasures: Computer Punch CardsFor decades, computer programming and data entry required punch cards. Each card contained one statement or programming instruction. In some cases, changing the program involved rearranging the order of the cards. However, programs frequently required hundreds of punched cards. A keypunch operator used a keyboard-controlled card punching device, much like a typewriter keyboard, to create the cards which were then read into the computer with a reading device.

Photograph of Cryptologic Treasures: Women Working in the Machine Branch Key-punch section at Arlington Hall
Women working in the Machine Branch Key-punch Section at Arlington Hall.

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60 Years of Cryptologic Excellence: 1960s

From a cryptologic perspective, the war that raged in Indochina from the early 1960s until the mid-1970s was a time of supreme service and sacrifice. The National Security Agency supported a network of cryptologic professionals, military and civilian, throughout the Vietnam War. Sadly, many of those in harm's way gave their lives. The first soldier killed in combat in Vietnam was Specialist James Davis, an Army cryptologist advising South Vietnamese Radio Research units.

Voice Encryptor

Photograph of Cryptologic Treasures: David Kahn's 'Tonight Show' Transcript ExhibitThe KY-38 (NESTOR) was a "Manpack" analog radio voice encryption device based on transistor circuitry. Together with the PRC-72 radio, the "manpack" gear weighed about seventy-five pounds. The equipment was designed and brought on line quickly in the mid-1960s for use in the Vietnam War and was used into the 1980s. The cryptographic key was set using a KYK-38 which set the pins to the key. As a security measure, once the key was armed, if the door opened, the key setting automatically reset to the zero position.

Photograph of Cryptologic Treasures: Men of the U.S. Army's 9th Infantry Division calling for air support south of Long Vinh in South Vietnam
Men of the U.S. Army's 9th Infantry Division calling for air support south of Long Vinh in South Vietnam.

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60 Years of Cryptologic Excellence: 1970s

By the 1970s, the United States and the Soviet Union were in the midst of the Cold War. With the threat of Soviet domination looming over the free world, the National Security Agency focused its efforts on obtaining the information needed to not only prepare for war, but also to keep the peace. In this capacity, NSA took advantage of the explosion in computer technology. For example:

  • Control Data Corporation, a company whose origins go back to the Defense Department, developed what can be considered the first supercomputer, the CDC 6600.
  • The Department of Defense connected four research institutions' computers onto ARPANET, which eventually became the backbone of the Internet.
  • The National Bureau of Standards and NSA established data encryption standards (DES) to protect sensitive information transmissions between computers.

CLAW 1 Circuit Board & Memory Module

Photograph of Cryptologic Treasures: CLAW 1 Circuit Board and Memory ModuleThis circuit board and memory module are from a CDC 7600 designed by Seymour Cray while he worked at Control Data Corporation. The CDC 7600 was generally considered to be the fastest computer in the world at the time, and five times faster than its predecessor, the CDC 6600. Scientific and government institutions used FORTRAN programming to conduct complex mathematical processing on this second-generation supercomputer. The entire system had over 120 miles of hand wiring, a small-core memory of 65,000 60-bit words, and was freon cooled.

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60 Years of Cryptologic Excellence: 1980s-1990s

Despite the end of the Cold War, America's armed forces still faced a wide range of threats and challenges. From Grenada, Panama, and Kuwait to Haiti, Bosnia, and Kosovo, the United States military faced these challenges with the National Security Agency's support. Due to the vast improvements in communications technology, intelligence moved faster than ever before. In the end, the coalition forces, including the cryptologic components, accomplished their missions with marked efficiency, technical expertise, and, most importantly, limited casualties.

Cryptographic Keying Device

Photograph of Cryptologic Treasures: Cryptographic Keying DeviceThe KOK-1 keying device was used on multipurpose cryptographic communication systems. It set the cryptographic key by the use of switches. The 26 letters could be manually set to any of the 46 possible positions. Keying accessories, such as this, are necessary to guarantee secure communications between units ensuring the protection of critical information.

Military Field Computer

Photograph of Cryptologic Treasures: Military Field ComputerAdvances in computer technology finally allowed for small computers in military field applications. The sealed aluminum case of this SAIC computer protected against the environmental hazards found in battlefield situations such as water, sand, corrosion, extreme temperatures, and vibrations. It also provided EMI radiation shielding. It used Windows 95 as its operating system, a system most users were familiar with, and allowed operators to operate the device under battle conditions. The portable computer used 3.5" floppy drive technology and had the capability to connect to phone lines.

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60 Years of Cryptologic Excellence: 2000-Present

Today, globally, we face a new threat: Cyber Warfare. The future is in cyber security. True to its legacy of employing the best people and the best technology to protect our nation's security, the National Security Agency will have a major role in meeting the challenges of the future. Today, everyone is on the interconnected, global network. America's business and government run on that network. Working together with other intelligence agencies and private industry, NSA strives to protect our vital infrastructure and communications systems from those that would do it harm.

DEFCON 20 Badge

Photograph of Cryptologic Treasures: DEFCON 20 BadgeDEFCON is one of the largest conferences for the hacking community. Hackers, generally considered a threat to computer and communication networks, can also be an asset. Speaking at DEFCON 20 in July 2012, General Keith Alexander, Commander of U.S. Cyber Command and Director of NSA/CSS, said, "The hacker community and USG (U.S. Government) cyber community share some core values: we both see the Internet as an immensely positive force; we both believe information increases in value by sharing; we both respect protection of privacy and civil liberties; and we both oppose malicious and criminal behavior. We should build on this common ground because we have a shared responsibility to secure cyberspace."

SME PED

Photograph of Cryptologic Treasures: SME-PEDThe National Security Agency-developed Secure Mobile Environment Personal Encryption Device (SME-PED - pronounced SMEE-Ped) is a secure smart phone. It provides secure, portable access to classified information systems enabling users to send and receive both classified and unclassified telephone calls and email. It also gives users access to browse the Internet or secure web networks that are classified SECRET. And it all fits in the palm of your hand.

Working under a National Security Agency contract, General Dynamics developed the SME-PED for use by top-level leaders in the Department of Defense, Homeland Security, State Department, and even state governors.

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Friedman, Safford and Washington Exhibit

Photograph of Friedman, Safford and Washington ExhibitWhen Herbert O. Yardley left the employ of the U.S. Army, William F. Friedman, already employed to make codes, took on the additional task of codebreaking. He assembled a brilliant team of cryptanalysts that broke the Japanese diplomatic cipher machines that had replaced their earlier paper codes. Friedman is regarded as the father of American cryptology, having pioneered in communications security and cryptanalysis, as well as being a great teacher of the art.

What William Friedman was to the Army, Laurance Safford was to the Navy. Beginning in the mid-1920s with a staff of one (civilian cryptanalyst Agnes Driscoll), Safford assembled the nucleus of the team that broke the Japanese naval codes during World War II.

George Washington, while never a codebreaker himself, recognized the value of military intelligence, and used the secret arts, including codebreaking, in the epic struggle against Great Britain during the Revolutionary War.

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Hall of Honor Exhibit

Photograph of Hall of Honor ExhibitThe Hall of Honor was created in 1999 to pay special tribute to the pioneers and heroes who rendered distinguished service to American cryptology. The standards are high for induction into this great hall. The individuals honored were innovators over their entire careers or made major contributions to the structure and processes of American cryptology. The men and women who have been inducted to the Hall of Honor are all greats in the once silent world of cryptology.

In the early days of America's cryptologic effort, many of the "giants" did both Signals Intelligence and Information Assurance. They made important contributions to both offensive and defensive cryptology. As such, they were among the first inducted into the Hall of Honor.

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Looking for a Sign: Hobo Communication in the Depression

Photograph of Looking for a Sign: Hobo Communication in the Depression ExhibitThe origins of the term "Hobo" cannot be traced, but came into common usage by the end of the 19th century. But the history of hobos began decades earlier. Most modern hobos trace their lineage back to the building of the railroads and the end of the Civil War. Following the war, many veterans took jobs building the expanding railroads. During the Panic of 1873 and the depression that followed, men climbed aboard the freight trains in search of work. The situation repeated itself with the Great Depression of the 1930s.

In some places, hobos who drifted into town were not always welcome. In other places, they found those who were friendly and willing to help. Knowing where to go or whom to avoid was important to these travelers. So the hobo community developed a written communication system of signs. A symbol on a fence post, mailbox, or tree told other hobos what to expect in the town or from the homeowner.

During the Great Depression, the signs relayed information vital to a hobo's way of life. Some signs appear to have a visual connection to their meaning. (A drawing of a top hat means a wealthy man lives here.) Others seem to indicate no relationship between the meaning and the symbol. Therefore, the definitions and explanations of the approximately fifty different hobo signs had to be passed on. Perhaps the men shared this information while traveling together in a boxcar or while sitting around a campfire of a hobo jungle.

The signs were intentionally temporary and the chalk marks wore off in time. Like many in the 21st century, modern hobos use the technology of today to communicate. Thus the secret signs and symbols of hobos have passed into history and folklore. See samples of hobo signs.

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Hobo Communications: A Brief History of Hobos and Their Signs

Photograph of Hobo Communications: A Brief History of Hobos and Their Signs ExhibitThe origins of the term "Hobo" cannot be traced. A few suggestions have been put forward. Some say it comes from "Hoe Boy" because many migrant workers traveled with a hoe or other farming tool. Others claim it came from the soldiers returning from the Civil War, who were "Homeward Bound." Some suggest it is from the congenial greeting "Hello boy" that changed to " 'Lo boy" and "Lo bo" and finally to "Ho bo." Others think it came from the word hoosier, meaning a rustic individual, a frontiersman. There are even those who say it comes from the Latin Homo Bonus, meaning good man, or the French haut beaux, the highest of the handsome. Few, if any, of these explanations seem adequate.

The term "Hobo," however the word originated, came into common usage by the end of the 19th century. But the history of hobos began decades earlier. Though not called hobos, but frequently referred to merely as tramps, men had long been traveling around picking up work. Most modern hobos, however, trace their lineage back to the building of the railroads and the end of the Civil War.

Photograph of Hobo Communications: A Brief History of Hobos and Their Signs ExhibitMany Civil War veterans couldn't, or didn't want to, return home and took jobs with the expanding railroads. Between 1866 and 1873, 35,000 miles of new track was laid across the country, much of it as part of the Transcontinental Railroad. The laborers moved west with the track that they laid.

The Panic of 1873 and the depression that followed led men to climb aboard the freight trains in search of work. Jumping on slow-moving freights, they moved across the country following the different harvest seasons or working in mining or lumber camps. The situation repeated itself with the Great Depression of the 1930s. Thousands of men, in search of work, took to the rails and roads.

Photograph of Hobo Communications: A Brief History of Hobos and Their Signs ExhibitOne trait hobos have in common is that they travel and work. They take pride in this attribute and often travel with the implements of their trade. In the 1880s, they began to distinguish themselves from "tramps" and "bums." Hobos have a work ethic. They willingly work for pay or food. In fact, they travel around the country as workers, not only because they enjoy the freedom, but also to earn a stake to get them through the winter. Tramps, as defined by the hobos, are people who travel, but prefer not to work, and bums neither travel nor work.

Although inextricably linked with the trains, some hobos traveled by car, others on foot. They traveled to work and worked to travel - the lifestyle of a hobo. A hobo's life could be exciting and dangerous, fulfilling and lonely, easygoing and difficult. The hobos sought not only employment, but also the freedom and independence the life allotted them. But that life also came with hardships and danger.

Photograph of Hobo Communications: A Brief History of Hobos and Their Signs ExhibitNot only is hopping a train illegal, it is extremely dangerous. Many hobos were killed or injured while trying to board or jump off a moving freight train. Others became locked inside box or refrigerator cars, their bodies found weeks later. Some hobos found places on trains to hide from the "bulls" who policed the cars, only to be crushed when the freight shifted. Still, despite the inherent hazards, thousands of hobos in the Depression made "rail riding" their chosen form of transportation.

Among the hardships of the hobo life were the attitudes and prejudices hobos faced from the townspeople and farmers they met along their way. All hobos felt the anger of local residents who thought hobos were lazy tramps looking for a free handout or were taking work from local men. Black hobos faced additional discrimination. However, during the Depression, the prejudice and ill-treatment they endured came more often from the law rather than from their brethren hobos. Although very few in number, women hobos faced the fear, and occasional reality, of assault in addition to the dangers and hardships the male hobos suffered.

In some places, hobos who drifted into town were not always welcome. In other places, they found those who were friendly and willing to help. Knowing where to go or whom to avoid was important to these travelers. However, hobos' paths crossed infrequently, so the hobo community developed a written communication system of signs. Mysterious and temporary, these signs helped hobos move more safely around the country looking for work. A symbol on a mailbox, fence post, signpost, or tree told other hobos what to expect in the town or from the homeowner.

The origin of the signs, like the Hobo name, is lost to history, but some of the symbols and their meanings have been documented. Carl Liungman's Dictionary of Symbols makes a connection between the hobo signs in the U.S. with those in England and the gypsy signs used in Sweden. A few of the symbols are the same. Several look the same, but have a different meaning. And still more are completely different, even if the information being relayed is similar. Like any language, written or spoken, over time it develops independently to meet the needs of those using it.

What's interesting to note, as Liungman points out, is that the system developed at all. Hobos, in general, travel alone and enjoy their independence. And yet, they still congregate in hobo jungles or travel with an occasional partner only to split when they decide to go a different way. Despite this preference for solitude, they still feel a certain camaraderie with their fellow hobos, an obligation to assist their brethren - thus, the creation of the signs and symbols.

Some of the signs appear to have a visual connection to their meaning. A drawing of a top hat means a wealthy man lives here. Others seem to indicate no relationship between the meaning and the symbol. A good code system makes no intuitive correlation between the code and its meaning. However, this then requires an explanation for the intended user. The definitions and explanations of the approximately fifty different hobo signs had to be passed on. Perhaps experienced hobos told young men what to look for as they traveled in a boxcar or sat at the campfire of a hobo jungle near a train yard.

The signs relayed information concerning a variety of topics important to the hobo. Symbols indicated where one could find a meal and whether work would be required first. Some signs described whether the police in town were friendly or that a hobo should keep moving. During the depression of the 1930s, Prohibition was also the law. Signs told whether a town was "dry." Other symbols marked a good location to catch a train. All of it was information a hobo could use.

The signs were intentionally temporary. Hobos used chalk or charcoal to mark an immediate location. The signs wore off in time. This may have been because situations were frequently in flux. A farmer may initially be helpful, but later, as resources or work diminished, he may order the hobo away. A woman who first took pity from a hobo's sad tale may become hardened after hearing too many.

No one knows exactly when or how the signs were created, nor are they in use today. Information for today's hobo is equally important, but in our modern world even the hobos make use of the communication systems on the Internet. With free access available in many libraries and community centers, hobos are no longer dependent on chalk marks. They have websites and email to share details of their travels and upcoming hobo events.

Interestingly, however, chalk marks similar to the hobo signs sprang up in 2002 precisely because of the Internet. "Warchalking" used symbols to mark areas of unsecured wireless networks. Like the hobos of the 20th century marking a good place to hop a freight train, just a few years ago travelers with a wireless card could, in some cases illegally, make use of these unsecured nodes for their PDAs and notebooks. The practice of "warchalking" was short-lived, however. New technological advances in wireless security and the advent of accessible Wi-Fi Zones put an end to the need for "warchalking." Wi-Fi Zones are widely available to travelers and, in some cases, are free. Their locations are clearly and more permanently marked than any hobo sign ever was.

Despite the many predictions that hobos would soon be a thing of the past due to the reduction in railroad lines, the faster diesel trains, and few jobs for seasonal workers, hobos still exist today. Some still engage in the dangerous and illegal practice of hopping freight cars; others drive the roads. Today, signs of hobos can be found in places like bridges and overpasses written in permanent marker. They may list the hobo's name, date, and his next destination. But gone are the secret signs and symbols of their predecessors.

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Information Assurance Exhibit

Photograph of Information Assurance ExhibitNSA's Information Assurance (IA) Directorate provides the solutions, products, and services that protect all classified and sensitive information infrastructures critical to U.S. national security. The Information Assurance gallery highlights the many fronts on which the IA mission has strengthened and enhanced the protection of U.S. information systems from the early twentieth century to the present day.

Exhibits show the march of technology and how it was pushed, in many ways, by NSA's communications security (COMSEC) developments. Artifacts include early 20th-century prototypes of COMSEC devices, never-before-exhibited equipment from the World War II era through 1990, and equipment still in use today or just ready to be fielded. Visitors to the gallery can hear the evolution of secure voice telephone communications with SIGSALY and see first-hand the use of biometrics and how measurements of fingerprints are made and used to verify identity.

In today's post-Cold War environment, there are many new concerns to U.S. communication and information systems. From traditional methods of intercept to ever-changing network viruses and intrusions, the Information Assurance Directorate (IAD) has kept pace with its adversaries' attempts. Working with private industry, NSA ensures the security of vital information and communications for the future.

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The Kahn Collection

Photograph of The Kahn Collection ExhibitDr. David Kahn, Cryptologic historian and author, graciously donated his vast collection to the museum, through the National Cryptologic Museum Foundation (NCMF).

Cryptology has been a life-long interest of Dr. Kahn's and it culminated in his seminal work, The Codebreakers in 1967. Included in our exhibit are two of the original drafts Dr. Kahn wrote, and rewrote, before its publication. The Codebreakers brought attention to a subject few had even heard of before and earned Dr. Kahn a guest appearance on The Tonight Show with Orson Bean. Also on display is a transcript of that interview.

Studying cryptology and its history, in order to write his many books on the subject, required significant research. Dr. Kahn collected books, artifacts, articles, and material as his research progressed over the years. Eventually, in 2004, Dr. Kahn chose to donate his collection to the NCMF for the museum library. A few of the more interesting or unique items are now on display: autographed copies of Elements of Cryptanalysis by William Friedman and The American Black Chamber by Herbert Yardley; a French manual on protecting private conversations; and, as an example of the eclectic and diverse nature of collection, a Nazi propaganda program.

The rest of the collection, held as part of the 'National Cryptologic Museum Library' is currently being cataloged. Specific requests for scholarly research can be accommodated by scheduling an appointment.

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Korean War Exhibit

Photograph of Korean War ExhibitIn 1945, Korea was liberated from Japan, but split in two. The Soviet Union aligned with North Korea, the Democratic People's Republic of Korea (DPRK.) The United States allied with South Korea, the Republic of Korea.

On June 25, 1950, the North Koreans invaded the south. U.S.-led U.N. forces eventually pushed the DPRK back across the original dividing line, the 38th parallel. At that point, the Chinese entered the war and helped push the U.N. forces southward. The conflict continued for three years ending in 1953 with the signing of an armistice agreement.

Communications Intelligence played a role throughout the Korean War. Initially, the predecessor to the National Security Agency, the Armed Forces Security Agency (AFSA,) had no full-time collection against North Korea, nor even any Korean linguists. But in July 1950, analysis of Chinese civil communications indicated the movement of Chinese army elements to the Manchurian border, a forewarning of their involvement. AFSA rapidly trained personnel and turned its attention to Korea to support U.N. forces. Signals Intelligence, provided by AFSA, gave General Walker, commander of the U.N. forces, the information he needed to hold the Pusan Perimeter until General MacArthur's attack at Inchon.

By late 1951, Army low-level intelligence from buried sound-detecting devices yielded information on enemy movements, supplies, and casualty reports. The new Air Force Security Service, with intercept sites along U.N. held islands near North Korea, provided near real-time information to its pilots flying over the DPRK, resulting in major successes in "MiG Alley."

The purpose of wartime cryptology is to support the nation's objectives and save American lives. During the Korean War, communications intelligence accomplished these goals but not without losses of their own.

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Language Exhibit

Photograph of Language ExhibitThis exhibit stresses the importance of language in the National Security Agency's mission. The exhibit has two major themes.

First, the exhibit explores the complexity of languages and provides facts on characteristics and relationships of diverse languages of the world. The exhibit features a replica of the Rosetta Stone, the key to understanding Egyptian hieroglyphics, which was incomprehensible for nearly 2000 years before its discovery.

Second, the exhibit offers a glimpse of the intricate world of cryptologic language analysts and their critical role in helping policymakers and warfighters defend our nation. It explains the complex and interesting process used by cryptologic language analysts in solving cryptologic problems. The presentation highlights several legendary heroes of language analysis and explains how their contributions helped America and the Free World to meet the many language-related challenges of the past.

The exhibit also features a computer kiosk that allows visitors to view a message by NSA's Director and to try out their language skills in interactive games.

This display serves as a reminder of the essential role cryptologic language analysts have played in the past and how critical they are in meeting the requirements of the present and the future.

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The Magic of Purple Exhibit

Purple Fact Sheet

Photograph of Purple Fact Sheet ExhibitOn a June morning in 1930 William Friedman, Chief of the Army's Signals Intelligence Service (SIS), and three members of his staff headed down a long corridor in a deserted part of the Munitions Building. Throwing open the two large doors that led into the vault area, Friedman lit a match and announced, "Welcome, gentlemen, to the archives of the American Black Chamber."

Established in 1919 the Chamber had once been America's main cryptologic workhorse. Friedman hoped to determine if any of the information found in the Chamber's files could shed light on current Japanese systems.

By the mid-1930s, Frank Rowlett, the senior member of the group, headed up a robust effort to break the first of two important Japanese diplomatic systems. Dubbed the Red Code, the elements of the system were a mystery. For months, Rowlett and his team endured long days and even more sleepless nights. Finally, a breakthrough occurred one evening. Rowlett remembered that from the hundreds of messages he had examined, three in particular were exceedingly long. If by chance those messages were enciphered on the same particular machine, it might be possible to discern a pattern that resembled certain Japanese words.

The following morning, the team put Rowlett's epiphany to the test. By noon they were on their way to solving the Red Code. But the benefits culled from the Red Code would only last so long. In 1939 the Japanese upgraded to a new machine driven cipher that SIS called "Purple." Despite their earlier success, the team realized that Purple was more complex than the previous Red system. For the next 18 months the codebreakers were in the dark.

Thankfully, for a brief period the Japanese used both the Red and Purple machines on some diplomatic circuits. By monitoring specific stations, the team could predict the first few words of each message. Using the many "cribs," as the cryptologic clues were called, the team discerned that, in the text of Purple messages, six letters were always treated differently than the other 20. Through pen and paper analysis, the team regularly uncovered the shuffling sequence and determined which of the six letters stood apart from the other 20 each day.

But pen and paper analysis was not fast enough to crack the system on a timely basis. To conquer Purple, the team needed to build a device that could mimic the machine's scrambling pattern. The fact was, however, that no westerner had ever seen a Purple machine.

The challenge of building the device fell to Leo Rosen, a MIT educated Army officer. One day, while leafing through an electrical supply catalog, Rosen noticed a device called "the uniselector." The device consisted of six telephone stepping switches bunched together that ran through 25 contacts. Quickly, he ordered two of the devices built, what would come to be known as, the "six buster."

Conquering the "sixes" was critical, but there was still the even more difficult challenge of the "twenties." Luckily, by September 1940, the Purple team knew enough to uncover the general patterns required to crack the remaining 20 letters.

Using the insights culled from the conquering of the sixes and the twenties, Rosen made the additional modifications to his original prototype. Each section of the "Purple analog" connected to the next through 500 wires. Lastly, Rosen added a typewriter to feed the encrypted traffic into the device and an additional typewriter to spit out the deciphered text.

Incredibly, after countless hours of painstaking effort, the work was finally done. It was time to test the system. Historian Stephen Budiansky notes.

"Late one night, Rosen and Rowlett plugged in the power supply and flipped the main switch. Rowlett began to type in the cipher text of a Purple message. The two cryptanalysts watched in awe as deciphered Japanese text began to emerge from the printer."

The breaking of Purple would be of immense help in understanding Japan's diplomatic strategy before Pearl Harbor. But as great a success as Purple was, there was a distinct downside. Generals and admirals dwell in far different worlds than those who negotiate treaties. The stunning success of Purple distracted the U.S. cryptologic community from the true indicator of Japanese intentions, the naval code.

Thus on the evening of 7 December 1941, the Pacific Fleet lay in ruins and those like Frank Rowlett, who were responsible for predicting just such an event, faced the future with a mixture of regret for past sins of omission and a willing determination to do better.

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Museum Library

Photograph of Museum Library ExhibitThe National Cryptologic Museum has had an adjunct reference library since it opened in 1993. The library supports not only the exhibits, but also encourages visitors to research various areas of cryptologic history. Over the years, the library has become an important resource to students, scholars, and those with an interest in this once secret world.

The Museum Library maintains a collection of unclassified and declassified books and documents relating to every aspect of cryptology. The books and records complement the museum exhibits and artifacts, but also offer unique and in-depth sources of information for researchers.

The library has a very large collection of commercial codebooks. These codebooks were used by all manner of businesses to reduce the costs of cable communications as well as to provide a measure of security for trade secrets. Modern communications and encryption methods have made these books obsolete and are mainly of historical interest. Some of the most sought after items in the library include the declassified documents. The Museum Library holds all of the released VENONA documents. NSA's Special Research Histories (SRH) provide documentation of NSA's predecessor organizations in the U.S. Army and Navy's cryptologic services. The SRH collection (available in its entirety at the National Archives in Record Group 457) consists of declassified reports dating predominantly to World War II. The library also holds some of the oral histories taken by NSA's Center for Cryptologic History.

These oral histories provide a detailed and personal view from a few of the people who have been a part of world events, including a radio intercept operator prior to WWI and Navajo Code Talkers (PDF Format).

A few select, unclassified monographs are also available to the public from the Museum Library. They cover a wide range of cryptologic subjects from early American ciphers to the Vietnam War. Most of the monographs were written and published by NSA's Center for Cryptologic History. These monographs go into greater depth than the museum exhibits or museum pamphlets and help to provide a greater understanding of the events in which cryptology played a role in world history.

The Museum Library is open to the public, however the hours vary.  Please call ahead to ensure that a staff member will be present to assist you (301-688-2145). The library is non-circulating, but photocopying is permitted.

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Postal Metering Exhibit

Photograph of Postal Metering ExhibitThe United States Postal Service (USPS) processes over 200 billion pieces of mail each year. Approximately 25 percent of that mail uses printed metered stamps, or indicia. Ensuring the protection and accurate accounting of those indicia is a problem solved through cryptography.

This exhibit, courtesy of Pitney Bowes, shows some of the history of cryptography in metered mail. In 1920, the USPS permitted the first use of indicia and Pitney Bowes produced a system that securely stored, accounted, and dispensed postage through its postage meter machine. In 1979, the first commercial application of remote transaction systems was introduced. It used a meter-specific one-time pad that was physically implemented as code on mylar tape. Today, digital signature and message authentication code are used to ensure integrity and authenticity of indicia information. The indicia information is encoded by a two-dimensional bar code. The 2D barcode encodes unique indicium and digital signature information to ensure integrity and authenticity.

This display stands as one example of how cryptology plays a role in everyday life and is not solely the auspices of the government and military.

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Rare Book Collection Exhibit

Photograph of Rare Book Collection ExhibitThe rare book collection includes books believed to have been acquired during the 1930s by the small group of individuals who worked for Mr. William Friedman. The books are not codebooks in themselves but are texts that elaborate on the science of cryptography. During the 1930s, American cryptology was being reborn after the 1929 closing of Herbert Yardley's Black Chamber  in New York City. Those coming into the field learned the business from the ground up, hence the need to study even ancient texts on the subject.

The collection includes an extremely rare copy of the first book ever written in the Western world on the subject of cryptology, Polygraphiae by Johannes Trithemius. Although an abbot, some believed his works on steganography and cryptology were inspired by demonic influences, an accusation he denied but didn't fight. Because of the controversial matter, Polygraphiae was not published until 1518, two years after his death.

Other books in the museum collection date back to the 16th century as well and many include notes made in the margins by the students using them in the 20th century. Some in the collection also have date-due cards in them, as they were part of NSA's library collection for a time. Not every book in the museum's collection is on display. Others can be found in the National Cryptologic Museum Library which is open to the public for research.

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September 11th Memorial Exhibit

Photograph of September 11th Memorial ExhibitIn silent tribute to the more than 3,000 innocent people killed during the three separate terrorists attacks on 11 September 2001, a scorched 12" x 17" concrete remnant of the outer wall of the Pentagon is exhibited in the Memorial Hall area of the museum. Surrounding the remnant are four statements by President George W. Bush on America's resolve to win the War on Terrorism. They are:

"We will not tire, we will not falter, and we will not fail." 9-20-01

"We will come together to strengthen our national intelligence capabilities to know the plans of the terrorists before they act." 9-20-01

"Some victories will be won outside of public view, in tragedies avoided and threats eliminated." 9-29-01

"None of us will ever forget this day. Yet, we go forward to defend freedom and all that is good and just in our world." 9-11-01

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Vietnam War Exhibit

Photograph of Vietnam War ExhibitCryptologic involvement in Vietnam began in the earliest days of the conflict. Servicemen arrived in the early 1960s to provide support and training to the South Vietnamese. Their efforts were not without difficulties.

Numerous fixed field sites in Vietnam conducted both strategic and tactical collection missions as well as radio direction finding (DF) In fact, it was on a DF mission that the U.S. Army lost one of its first soldiers in Vietnam, SPC4 James Davis, in 1961. By 1966, the fixed sites were also doing border surveillance and infiltration interdiction along the Vietnam-Laos-Cambodia border. The Army Security Agency, the cryptologic branch of the Army, used a wide variety of aircraft as well to conduct aerial reconnaissance missions. Three Army crews lost their lives while conducting aerial signals intelligence missions in Southeast Asia.

The U.S. Navy also began its surveillance as early as 1962, conducting shore, shipborne and aerial reconnaissance. By 1964, the missions included "all-source intelligence." They photographed items of interest on the coast and monitored coastal radar activity to provide information on Viet Cong supply routes. In August 1964, the attacks on the U.S.S. Maddox and Turner Joy were the first open conflicts between the U.S. and the North Vietnamese forces. The Vietnam War began.

Throughout the war, all military services' cryptologic elements took part in providing tactical and strategic information to military commanders. Information derived from signals and electronic intelligence flowed quickly back to the commanders in the field. The National Security Agency also sent civilians to Vietnam to assist with the effort. They worked side by side with their military counterparts and the South Vietnamese. Those stationed at NSA in the United States worked around-the-clock processing, translating, and forwarding this vital intelligence.

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Women in American Cryptology Exhibit

Photograph of Women in American Cryptology ExhibitAlthough the number of women involved in cryptology has always been lower than the number of men, they have not been completely absent from the field either. Women have always been involved in America's cryptologic history. Some have reached the higher ranks of management and a few have been considered the expert in their field.

Cryptologic pioneers, such as Elizebeth Friedman and Agnes Driscoll, are well known to those who study cryptology. Were it not for their early involvement, the women of today may not have been able to reach their current numbers or status. But not every woman, or their organizations, has made it into the history books. Thousands of lesser-known women cryptologists have also played a role in creating the legacy women enjoy today. Their achievements, and in some cases their escapades, furthered the progress of women in cryptology. Women's involvement was sometimes sporadic, but significant.

The exhibit highlights the contributions of a twenty-four women who have helped create cryptologic history. The display begins with a member of the Culper Spy Ring during the American Revolution who used her laundry as a secret code. Women spies from the Civil War also used codes and ciphers to aid those fighting for the causes they believed in. But it wasn't until the twentieth century that women began to work full-time in cryptology. During WWI several women considered to cryptologic pioneers began their careers, as did some women few people today would know. During WWII thousands of women joined the military or worked as civilians for the military as cryptanalysts, intercept operators, technicians, machinists and every other position available in cryptology. Many of those women chose to stay in the field after the war providing breakthroughs and contributions throughout the Cold War. Eventually, women rose to the highest ranks of management and today continue to support, develop, and build the cryptologic legacy of tomorrow.

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World War 1: American Black Chamber Exhibit

Photograph of World War 1: American Black Chamber ExhibitThis exhibit details the checkered career of Herbert O. Yardley (1889-1958), who headed the highly secret MI-8, or the "Black Chamber." Yardley began his career as a code clerk with the U.S. State Department, and during that service discovered his natural talent as a cryptanalyst. During World War I, Yardley served in the cryptologic section of Military Intelligence (MI) with the American Expeditionary Forces.

After the war, Yardley lead the first peacetime cryptanalytic organization in the United States, MI-8. Funded by the Army and the State Department, MI-8, was disguised as a New York City company that made commercial codes for businesses. However, their actual mission was to break the diplomatic codes of different nations. A mission they were initially quite successful at completing, breaking codes from several foreign countries.

MI-8 had an early success: in 1921-22, Yardley and his staff solved the cipher system used by Japanese negotiators at the Washington Naval Conference. They fed the decrypts to the U.S. chief negotiator, Charles Evans Hughes. The messages contained the Japanese's minimum demands at the conference. Hughes appeared to be outsmarting the Japanese to obtain a more favorable agreement on naval capital ships, when actually he was reading their negotiating position every day before he went into the bargaining sessions.

In 1929, the State Department closed down MI-8. According to legend, Secretary of State Henry Stimson at that time spoke the famous sentence: "Gentlemen do not read each other's mail." Disappointed, unemployed, and accustomed to luxury, Yardley found himself in need of finances and in possession of his country's secrets. He wrote The American Black Chamber, which revealed to the world the work of MI-8. It became an international best seller. Needless to say, the Army, which continued codebreaking, was not amused. And the Japanese, for their part, changed their code systems. Surprisingly, at the time, the wording of the espionage laws contained a loophole that prevented the government from prosecuting Yardley.

Yardley, a brilliant cryptanalyst, as well as a promoter of the cryptologic cause, continued to provide expertise to various countries, but never again worked for the United States.

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World War 1: Radio Intercept Site Exhibit

Photograph of World War 1: Radio Intercept Site ExhibitThis site is a mock-up of the World War I intercept site in Verdun, France. The exhibit is based on two pictures of the original shack. Just as American combat troops in the "Great War" frequently had to fight with foreign equipment, intercept activities were also often conducted with foreign equipment: in this case, the radios shown are of French manufacture.

Intercepting the enemy's radio communication was imperative for success during WWI. At the outbreak of war in August 1914, the German Army successfully used vital radio intercepts, enabling them to defeat the Russian 2nd Army in the Battle of Tannenberg. Soon all the major participants in World War I would go on to use more encompassing communications intelligence (COMINT) with varying degrees of success.

U.S. Army radio intercept operators went into the field during General Pershing's Punitive Expedition, an attempt to capture the Mexican revolutionary, Pancho Villa, along the Mexican Border in 1916. But the first large scale use of Army radio intelligence personnel was during World War I.

Although signals intelligence was in its infancy, and radio was the new communications technology, the U.S. Army's Radio Intelligence Section used their newfound capabilities to "spy" on enemy conversation. Signals could be intercepted without being in close proximity to the transmitter or transmission lines and could provide vital information about enemy tactics and strategy. This information was gained from direction finding, radio intercept and decryption and was used for tactical planning by the American Expeditionary Forces.

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World War 1: Zimmermann Telegram Exhibit

Photograph of World War 1: Zimmermann Telegram ExhibitIn an effort to tip the balance in their favor, and still keep the Americans out of World War I, Germany devised a plan and asked Mexico for its assistance. The plan involved cutting off supply lines to Britain and France by beginning unrestricted submarine warfare in the Atlantic. Fearing the United States would join the battle if their ships were sunk, Germany asked Mexico to start a war with the United States and promised the return of Texas, Arizona, and New Mexico.

Germany hoped a conflict in the Southwest would keep the Americans out of the European war. The request was sent from the foreign minister in Berlin, Arthur Zimmermann, through the German ambassador in Washington DC to the German ambassador in Mexico City, in the form of a coded message. It became known as "The Zimmermann Telegram" and it changed the course of world history.

Britain intercepted the message as it was transmitted overseas. Royal Navy cryptanalysts decoded it. Realizing they held the key to the United States' participation in the war, Britain, through a little subterfuge, eventually showed the message to the United States. There were those in the Congress that suspected Britain of creating a false message so that the United States would lend assistance to their fight. To verify its authenticity, a copy of the Western Union message that was sent from DC to Mexico City was supplied and Britain's cryptanalysts decoded it in the presence of the U.S. ambassadors to England. This convinced the doubters and Congress declared war on Germany. Thus, a single coded message, and the efforts of cryptanalysts, changed history.

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World War 2: Battle of Midway Exhibit

Photograph of World War 2: Battle of Midway ExhibitThe Battle of Midway is frequently referred to as "the turning point in the Pacific." After a series of losses, the United States won a decisive victory over the Japanese Imperial fleet. Damages to the Japanese carrier fleet were insurmountable and their momentum was broken. The Japanese were never able to replace the four aircraft carriers and 332 aircraft. Nor could they replace their top, combat tested, pilots, lost in the battle. After the Battle of Midway, the Japanese Navy fought defensively in the Pacific rather than offensively.

The Japanese had hoped to surprise the American military on Midway Island and claim this crucial location. However, American Navy cryptologists stationed in Hawaii had made some breaks into the Japanese Navy Fleet Code, known to cryptanalysts as JN-25B. Although they were breaking less than 15% of JN-25, CDR Rochefort, the Officer-In-Charge of the cryptanalysts, came to believe that the Japanese were planning to attack a target codenamed AF. Rochefort believed AF referred to Midway. With the approval of RADM Nimitz, instructions were given to the Marines on Midway to send a plaintext message complaining about the lack of fresh water. Two days later, 12 May 1942, a JN-25 message was decoded stating: "AF is short of water."

Knowing Midway would be attacked, the U.S. Navy and Marines were able to adjust their forces and combat the attack head on. Although the battle raged for portions of three days, and significant numbers of U.S. and Japanese lives were lost, the Americans defeated the Japanese fleet. The U.S. lost 307 men, one carrier (the Yorktown,) one destroyer, and 147 aircraft. The Japanese lost 2,500 men, four carriers, one heavy cruiser, and 332 aircraft.

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World War 2: 'Big' Machines Exhibit

The Germans referred to the U.S. machine, SIGABA, as the 'Big' machine, hence the name of this exhibit. The collection of 'Big' machines in the exhibit encompasses several different, high-level, encryption machines used during World War II by the U.S. and its adversaries. 'Big' machines of this era were generally suited for fixed-station or ship-borne secure communications.

SIGABA/ECM

Photograph of World War 2: 'Big' Machines SIGABA/ECM ExhibitThe U.S. Army's SIGABA, called the ECM (Electric Cipher Machine) in the Navy, was the only machine system used during World War II to remain completely unbroken by an enemy. It utilized the same principle of rotating, removable, wired rotor wheels that the German Enigma employed. However, unlike the stepping motion of the Enigma, the SIGABA/ECM's motion appeared to be random. It wasn't, but it was so complicated, the German's never broke it, and the Japanese gave up trying.

Frank Rowlett of the Army's Signal Intelligence Service developed the complicated stepping motion. Ten of SIGABA's twenty rotors could be taken out and moved to a different position; the rotors could be placed in the machine either "forward" or "backward;" and any one or more of the rotors could move with each keystroke. This differs dramatically from the predictable motion of the Enigma that required its first rotor to move one step with each keystroke and the other rotors stepped in sequence. This proved to be one of the greatest flaws in the Enigma, a lesson the Americans learned and were able to improve on when developing their SIGABA/ECM.

Tunny and Sturgeon

The Tunny and Sturgeon machines (referred to by American and British cryptologists as the "Fish" machines) were both on-line cipher machines. Messages could be simultaneously enciphered and transmitted, saving a great deal of time. Although a British cryptanalytic attack made considerable progress, the results were far slimmer than against the Enigma, both because the difficulty of attack yielded fewer breaks and because a lot less traffic was sent over these systems.

Photograph of World War 2: 'Big' Machines Tunny ExhibitThe Tunny (which is British slang for Tuna) was a German Army machine that could be used out of the back of a truck as well as at a fixed site. To create its encryption, the Tunny used the international telegraphic "Baudot" cipher and an additive placed on the cipher by the rotors. It was used to stream high-level teleprinter messages. The British built the first large valve programmable computer, Colossus, to decrypt Tunny messages, cutting decrypt time from weeks to hours.

Photograph of World War 2: 'Big' Machines Sturgeon ExhibitThe Sturgeon was primarily a German Air Force system. It was capable of high-speed teleprinter transmissions. This particular machine used cable rather than radio to transmit its messages, thus decreasing the Allies' ability to intercept. A Swedish mathematician, Arne Beurling, was the first to break the Sturgeon, a feat he accomplished in just two weeks.

Jade and Purple

Intended for high-level encryption, the Japanese family of machines using telephone selector switches came to be known in the United States by their 'color' codenames: Coral, Jade and Purple. The switches performed the same function as a wired rotor, stepping forward through each of the 25 contacts. However, unlike wired rotors, the switches could not be taken out and rearranged, a serious limitation to the system. The Japanese Imperial Navy used the Jade machines for its high-level encryption of the katakana syllabary. Its keyboard used a shift key and 25 letter keys to create the 48 characters. Most machines were aboard ship, but this Jade was captured on Saipan when U.S. forces took the island in June 1944.

Photograph of World War 2: 'Big' Machines Jade ExhibitThe Japanese diplomatic system, codenamed Purple, differed from Jade in that it included a plugboard. Twenty letters could be plugged and routed through three units, while the other six letters went through only one. For the Army's Signal Intelligence Service, breaking of the "sixes" was not terribly complicated; however, the "twenties" appeared to be completely different from any known system. After determining that telephone-switching units could be the basis for the machine, the cryptanalysts, after 18 months of analysis, eventually broke Purple. Some believe this to be the greatest feat in cryptologic history.

Photograph of World War 2: 'Big' Machines Purple ExhibitOn display is the Army's first analog machine used to decrypt Purple enciphered messages. This machine solved the famous fourteen-part message telling the Japanese ambassador to break relations with the United States on December 7th at 1:00 p.m. Although it arrived on the night prior to the attack on Pearl Harbor, the Japanese did not decipher it until after noon on December 7th and were unable to present it to the U.S. until after 2:00. The Signal Intelligence Service, using this analog, had decrypted the message by 5:00 a.m. Unfortunately, it contained no military information concerning an attack, just an end to diplomatic relations. War was clearly imminent, but the message lacked details.

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World War 2: Code Talkers Exhibit

Photograph of World War 2: Code Talkers ExhibitSurrounded by complex machines, the exhibit on Native American Code Talkers appears out of place, but it is actually a monument to the most complex machine of all - the human mind.

Having suffered losses in the First World War as a result of the Germans listening to U.S. communications, the commander of the U.S. Army's 142nd Infantry Regiment found a solution. Captain Lawrence overheard two Choctaws speaking in their own language. He arranged for them to become radio communicators. They used common words to replace military terms and spoke Choctaw, thus becoming the first Code Talkers.

On 26 October 1918, in northern France's Argonne Forest, the Choctaws' communications resulted in a completely successful surprise attack against the Germans. Initially there were eight Choctaw Code Talkers, but with subsequent successes, six more were quickly trained.

Germany and Japan sent students to study the Native American cultures and languages following WWI. For this reason, there were many in the U.S. military services who were concerned that the use of code talkers in the Second World War would be insecure. However, the Army did continue the program and during World War II recruited Commanches, Choctaws, Kiowas, Winnebagos, Seminoles, Navajos, Hopis, Cherokees and others.

The Marine Corps took the Army work and codified, expanded, refined and perfected it into a true security discipline, using Navajos exclusively. The Marine Corps felt the Navajo language would be more secure for several reasons: the language was virtually unknown outside the Navajo nation, it was unwritten, and it was so complex, involving tonal inflections, that it was difficult to learn as an adult. The original 29 recruits began training in May 1942. Over the course of the war, approximately 400 Navajos (and one Caucasian) became part of this very successful code talking program. In campaigns against the enemy on many fronts, the Native American Code Talkers never made a mistake in transmission nor were their codes ever broken.

In 2002, MGM Studios released the motion picture Windtalkers.

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World War 2: Enigma Exhibit

Photograph of World War 2: Enigma ExhibitPossibly the most well known of all cipher machines is the German Enigma. It became the workhorse of the German military services, used to encrypt tens of thousands of tactical messages throughout World War II. The number of mathematical permutations for every keystroke is astronomical. However, the Enigma is not famous for its outstanding security, but rather for its insecurities. Allied forces were able to read most of the Enigma encrypted messages throughout most of the war as a result of the tireless effort of many Allied cryptologists.

The principles on which The Enigma were based would make it seem like an uncompromising and secure device. It is an electromechanical machine that used a combination of wired rotors and plugs to change each letter as it is typed. The encryption process began by depressing a lettered key that generated an electrical current. The current passed through a plugboard and three rotors, a reflecting plate, and back through the three rotors and plugboard. The "letter" changed each time it encountered a plug, rotor, and the reflecting plate. Eventually, the cipher letter was illuminated on a light panel and the operator wrote that letter down. Because the first of the three rotors moved with each keystroke, the cipher letter changed, even if the same letter key was repeated.

The Germans had five (and the German Navy, eight) wired rotors from which to select three to be placed in the machine each day. A keylist was provided to each radio network for its Enigma units, telling the operator which rotors and plug settings to use that day. The Germans believed that, without the keylist, the Allies could never break the Enigma enciphered messages. Their unswerving belief in the machine's security proved to be their failing.

Beginning in 1928, the Polish Cipher Bureau began working to break the Enigma messages. In 1932, they assigned three mathematicians to do the work. They succeeded. Little more than one month before the outbreak of WWII, the Polish passed their secret to France and Britain. Despite the improvements made by the Germans during the war, Britain was able to continue finding the Enigma settings (without capturing keylists) and reading the Germans' messages. By the time the United States entered the war, the U-boat Enigmas had become even more complicated by the addition of a fourth rotor. Beginning in the fall of 1943, and for the rest of the war, the responsibility of solving the U-boat messages fell to the U.S. Navy. Breaking the four-rotor messages led directly to the Allies' victory in the Battle of the Atlantic.

Today, many historians believe that the Allies' ability to read the Enigma-enciphered messages and act on that information shortened the war by as many as two years, saving thousands of Allied and Axis lives.

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World War 2: SIGSALY Exhibit

Photograph of World War 2: SIGSALY ExhibitSIGSALY was the first secure voice encryption system for telephones. It was invented and built by Bell Telephone Laboratories in 1943. It had several technological "firsts" including pulse code modulation for speech transmission, multilevel frequency shift keying, and bandwidth compression.

The exhibit is a mock-up of one-third of the entire system, which weighed 55 tons and consisted of forty racks of equipment. It took thirteen people to operate and required fifteen minutes to set up a phone call. The first two units were installed in the Pentagon in Washington, DC and in the basement of a popular London department store. (It was too large to fit in Churchill's war chambers.) During and after the war, units were installed worldwide totaling twelve locations for secure telephonic communications.

SIGSALY used recordings of purely random noise for its security process. Both the sending and receiving station had copies of the acetate records and as one "encrypted" the voice, the other "decrypted." Understandably, voice quality was quite poor, but it was secure. SIGSALY was not broken by the Axis powers.

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World War 2: U.S. Navy Cryptanalytic Bombe Exhibit

Photograph of World War 2: U.S. Navy Cryptanalytic Bombe ExhibitThe U.S. Navy's Cryptanalytic Bombe is the culmination of years of work and the efforts of mathematicians and engineers from Poland, England, and the United States. It was the solution to the problem of the German's World War II cipher machine Enigma, and it led to the Allies' successes in the battle of the Atlantic and the war in Europe.

When the United States entered World War II, the British were already breaking and reading many of the German's tactical-level messages enciphered on the Enigma. Their success was a result of the work originally done by Polish mathematicians before the war. Throughout the 1930s Poland's machine, called "Bomba," kept pace with the German's Enigma until shortly before the war broke out. Britain improved on the Bomba and built hundreds of British "Bombes" to continue the effort. However, in 1942 a fourth rotor was added to the U-boat Enigmas and the original British Bombes were not able to find solutions to those messages.

Concerned about shipping losses, the U.S. Navy asked engineers at the National Cash Register Company (NCR) to redesign the Bombe to work against the four-rotor U-boat Enigmas. Within a year, NCR civilians, Navy sailors, and women in the Navy, known as WAVES (Women Accepted for Volunteer Emergency Service) began building and shipping the new Bombes to Washington, DC Between September 1943 and March 1945, 121 Bombes were installed at the Navy's Communications Annex in Washington DC.

The WAVES operated the Bombes working 24 hours a day, 7 days a week. They set the machines up and tested the results. The U.S. Navy Bombes rapidly searched the hundreds of thousands of possible settings on one wheel order of a four-rotor Enigma. (The German Navy had eight wired rotors from which to select three that went into the Enigmas. The fourth rotor remained in its position.) The U.S. Navy Bombes needed to try each combination of rotors until the correct wheel order was found. Fortunately, the machine was so well designed that each run took only 20 minutes, significantly faster than the British Bombes.

There were many different U-boat communication networks, each using a different daily setting. In order to make rapid use of the information that could be derived from decrypted Enigma messages, the Bombes had to find the settings for each network as quickly as possible. On average, settings were found by midday, some more rapidly. The U.S. Navy Cryptanalytic Bombes were so efficient that the British turned the entire U-boat problem over to the United States. Once the Bombes had found the U-boat networks' settings, the Navy Bombes assisted the British with the three-rotor German Army and Air Force Enigma-enciphered messages.

The Navy Bombes, and those who built and operated them, played a crucial role in saving both Allied and Axis lives and hastened the end of the war in the Atlantic and Europe.

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Date Posted: Jan 15, 2009 | Last Modified: Apr 09, 2013 | Last Reviewed: Apr 09, 2013

 
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