Welcome to the National Cryptologic Museum Foundation. The NCMF directly supports the National Cryptologic Museum (NCM), the first public museum in the U.S. Intelligence Community.

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Polish mathematicians & code breakers made the first breakthroughs against Nazi Germany's Enigma code.......

1942: Station HYPO began reading Japanese system JN-25.

Tuesday, March 5, 2019
1942: Station HYPO began reading Japanese system JN-25.

5 March 1942: Station HYPO started reading Japanese JN-25. Photo is of Captain Joseph Rochefort.

Commander Joseph Rochefort had been placed in command of Station Hypo, the Navy's codebreaking organization at Pearl Harbor. In 1942 Rochefort and his staff began to slowly make progress against JN-25, the Japanese Navy's operational code. If it could be broken, Rochefort would be able to provide Nimitz the information he needed to make wise and prudent decisions concerning the dispersal of his precious naval assets.

Breaking the Japanese code known to Americans as JN-25 was daunting. It consisted of approximately 45,000 five-digit numbers, each number representing a word or phrase. For transmission, the five-digit numbers were super-enciphered using an additive table. Breaking the code meant using mathematical analysis to strip off the additive, then analyzing usage patterns over time, determining the meaning of the five-digit numbers. This complex process presented a challenge to the officers and men of Station Hypo, but Rochefort and his staff were able to make progress because the system called for the repetitive use of the additive tables. This increased the code's vulnerability. Even so, the work was painfully slow. Prior to the attack on Pearl Harbor, only 10% to 15% of the code was being read. By June of 1942, however, Rochefort's staff was able to make educated guesses regarding the Japanese Navy's crucial next move.

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  • Government seizure of cryptologist Herbert Yardley's never-published book, "Japanese Diplomatic Secrets."

About Us

The NCMF directly supports the National Cryptologic Museum (NCM), the first public museum in the U.S. Intelligence Community. We think you will agree it is truly a "museum like no other."

Located adjacent to the National Security Agency (NSA) in Maryland, the NCM houses a priceless collection of artifacts that represent our Nation's history in code making and code breaking, as well as a world class library of cryptologic media. The NCMF acquires the best artifacts for the NCM and supports new educational and interactive exhibits.

The NCMF provides exceptional cryptologic programs throughout the year, encourages young minds to explore cryptology and innovation through valued awards, and hosts educational, cryptology-related exhibits at various community events.

As part of the Foundation's partnership with NSA to build the Cyber Center for Education and Innovation - Home of the National Cryptologic Museum (CCEI-NCM), the NCMF also serves as a leader in the field of cybersecurity - striving to provide the best in educational resources and programs.

The NCMF and NCM share a joint three-fold mission to Educate, Stimulate, and Commemorate. Learn more about our MISSION.