An omnibus edition of nine volumes of postwar histories declassified by the National Security Agency in 2010. The research was carried out by the Army Security Agency relying on captured documents and interviews with prisoners. This is an absolutely essential primary reference for anyone interested in cryptography as a vital aspect of World War II.

The volumes include:

Volume I: Synopsis

Volume 2: Notes on German High Level Cryptography and Cryptanalysis

Volume 3: The Signal Intelligence Agency of the Supreme Command, Armed Forces

Volume 4: The Signal Intelligence Service of the Army High Command

Volume 5: The German Air Force Signal Intelligence Service

Volume 6: The Foreign Office Cryptanalytic Section

Volume 7: Goering's "Research" Bureau

Volume 8: Miscellaneous

Volume 9: German Traffic Analysis of Russian Communications

As the German military grew in the late 1920s, it began looking for a better way to secure its communications. It found the answer in a new cryptographic machine called "Enigma." The Germans believed the encryption generated by the machine to be unbreakable. With a theoretical number of ciphering possibilities of 3 X 10114, their belief was not unjustified.1 However, they never reached that theoretical level of security. Nor did they count on the cryptanalytic abilities of their adversaries. The Enigma machine based its cipher capabilities on a series of wired rotor wheels and a plugboard. Through a web of internal wiring, each of the 26 input contacts on the rotor were connected to a different output contact. The wiring connections of one rotor differed from the connections on any other rotor. Additionally, each rotor had a moveable placement notch found on an outer ring. The notch forced the rotor to its left to step one place forward. This notch could be moved to a different point on the rotor by rotating the outer ring. The Germans followed a daily list, known as a key list, to indicate where the notch should be placed each day. Another complication to the machine involved the plugboard, which the Germans called a "Stecker." The plugboard simply connected one letter to a different letter. That also meant that the second letter automatically connected back to the first. Again, the key list indicated which letters should be connected for that day. Each day, the Germans followed the key list to plug the plugboard connections, select the rotors to be placed in the machine, change the rotor notch placement, and place the rotors in the left, center, or right position within the machine. Finally, the code clerk chose which three letters were to appear through three small windows next to the rotors. These letters indicated the initial rotor settings for any given message, and the code clerk changed those settings with every message he sent. The path the electrical current took initiated with the keystroke. The current passed through the plugboard, changing its path if that letter was plugged to a different letter. From there it entered the first, or rightmost, rotor at the input contact. The rotor wiring redirected it to a different output that went directly into the next rotor's input. After passing through, and changing directions in each rotor, the current entered a reflecting plate. This plate not only changed the "letter," but also sent the current back through the rotors, again resulting in three more changes. The current made one last pass through the stecker and finally on to the light panel where the cipher letter lit up. To decipher an Enigma message, the recipient had to have an Enigma with the same plugboard connections, rotors, notch placement, left/center/right positions, and initial settings. This enabled the current to follow the same pathway in reverse and resulted in the plaintext letter lighting up on the light panel. The Germans, with their published key lists, had the necessary information. The Allies did not. The Enigma eliminated whatever intricacies a language may possess that previous methods of cryptanalysis exploited. One such practice was frequency counts. Certain letters in any language are used more often than others. By counting which cipher letters appeared most often, cryptanalysts could make an assumption about which plaintext letter they represented. Machine encryption like the Enigma destroyed the frequency counts. Cipher letters tended to appear equally often.

In the late summer of 1781, General George Washington finally saw an opportunity to take New York City away from the British. Virtually from the beginning of the War for Independence six years earlier, the British held this key city and Washington long desired to take it into American hands. Washington laid siege to the town all summer. With the expected arrival of Admiral de Grasse and ships of the French fleet along with an additional 3,000 French soldiers, he believed he may finally have his chance. But on August 14th, he changed his mind and turned his eye to Yorktown, Virginia. Intelligence, gained partially through the decryption of captured British messages, gave Washington the assurance he needed to complete his move on Yorktown. Communication plays an important role in both a country's diplomacy and its wars. Even if that country doesn't yet exist. Keeping those communications secret, or the ability to understand the adversary's communications, can make the crucial difference in a leader's actions and abilities. At the time of the American Revolution, both the British and the American rebels practiced a variety of methods to keep their written communications secret. Both had networks of spies who needed to pass on their information right under the noses of their adversaries. Both turned to invisible inks, hidden messages, and secret writing in the form of ciphers and codes. Ciphers and codes, cryptography, change messages into something unintelligible by the use of keys and lists. Ciphers rearrange letters or change individual letters into a different letter, number, or symbol based on a prearranged setting known as a key. Codes change entire words or phrases into other words, number groups, or symbols based on a list or a book. To decrypt the secret messages, the receiver needs access to the original key. Theoretically, the adversary wouldn't have the key and therefore could not understand the message even if it was captured. Solving a message without having the key, cryptanalysis, has been a science employed by governments for as long as people have been using cryptography to make their messages secret. European governments have a long history of "Black Chambers" the offices where other countries' diplomatic mail was opened and read. If the message was encoded, a Black Chamber tried to solve the code and read the message. This is the story of revolutionary communications and cryptologic secrets and the role they played in America's war for independence.