William F. Friedman Collection of Official Papers

In one of its largest and most significant declassification and release of documents to date, the National Security Agency (NSA) released over 52,000 pages of historical material relating to the career of William. F. Friedman.

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About the Collection

Considered the dean of American Cryptology, William F. Friedman (1891–1969) was a pioneer in the field as one of the first to apply scientific principles to the making and breaking of codes. His most well-known accomplishment was leading a small team which broke Japan's "Purple" diplomatic cipher prior to the Pearl Harbor attack, but through his lectures, textbooks, and mentorship Friedman also trained several generations of American cryptologists, thus laying the foundation for the 20th century U.S. signals intelligence community.

NSA's William F. Friedman Collection consists of materials created and collected by Mr. Friedman over the course of his government career and comprising his official working files. The collection was augmented by documents related to Friedman's work and contributions to cryptology subsequently compiled by NSA historians and archivists. Covering almost 60 years, the records shed light on both the career of this legendary cryptologist and the history of American signals intelligence.

This collection, composed of over 52,000 pages in more than 7,600 documents, including some sound recordings and photographs, has been preserved in the NSA Archives for its historic significance and value. The bulk of the material dates from 1930–1955 and represents Mr. Friedman's work at the Signals Intelligence Service, the Signal Security Agency, the Armed Forces Security Agency, and NSA.

Please Note: The following historical documents are scanned images of formerly classified carbon paper and letters that have been declassified and saved as PDFs. Due to the age and poor quality of some of the images, a screen reader may not be able to process the images into word documents. In accordance with Sections 504 and 508 of the Rehabilitation Act of 1973, as amended, individuals may request that the government provide auxiliary aids, alternate formats, or services to ensure effective communication of the substance of the documents. For such requests, please contact the Public Affairs Office at 301-688-6524.

The contents of these folders have been reviewed and found to be properly classified in accordance with Executive Order 13526 – Classified National Security Information (https://www.whitehouse.gov/the-press-office/executive-order-classified-national-security-information). The contents of some of the folders remain classified because disclosure could reasonably be expected to cause damage to national security. NSA has listed these folders with the note, "Folder not releasable."