What did the declassified documents reveal?

Document Title: John Forbes Nash, Jr. Letters, National Security Agency Release Date: 2015-02-24 The Black Vault Entry: https://www.theblackvault.com/documentarchive/john-forbes-nash-jr-letters-national-security-agency/ Canonical PDF: https://documents.theblackvault.com/documents/nsa/nashletters1.pdf The National Security Agency released a collection of letters exchanged between the agency and mathematician John Forbes Nash, Jr. in the 1950s. These letters are notable for their discussion of cryptography and Nash's proposed enciphering-deciphering machine. The documents were released in response to a Freedom of Information Act request and are available on The Black Vault website. The letters were declassified in 2015. Please Note: These FOLLOWING historical documents are PDF images of formerly classified carbon paper and letters that have been declassified. Due to the age and poor quality of some of the PDF 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. MASSACHUSETTS INSTITUTE OF TECHNOLOGY CAMBRIDGE 39, MASS. DEPARTMENT OF MATHEMATICS MASSACHUSETTS INSTITUTE OF TECHNOLOGY CAMBRIDGE 39, MASS. DEPARTMENT OF MATHEMATICS } f.\4c ~~ v\s £t{ (. \?)1tR \wG - -~ / ir • John Nash Department of Mathematics Massachusetts Institute of Technology Cambridge 39, Massachusetts Dear Mr. Nash: I~ Serial: " "> Your recent letter, received " January 1955, is noted. 531 5 JAN 1955 Technicans at this Agency recall a very interesting discussion with you which took place approximately four years ago, and will welcome the opportunity to examine your ideas on the subject of cryptography. A check within this Agency has, unfortunately, disclosed no information on your machine. A description of the principles involved will be appreciated. cc: ' .. 4 AG Cis COMSEC (3) 412 Sincerely , Eo M. Gibson Lt. Col., AGe Assistant Adj. Gen. M/R: In Jan 1955, Mr. Nash offered general remarks on cryptography and requested evaluation of descriptive material which he had forwarded through Rand Corp. NSA Ser 236, 12 Jan 55 informed Mr. Nash that the material had not arrived. Mr. Nash in letter rec'd 18 Jan 55 states the material was sent to NSA and to a Navy Communication Center in Wash. late last spring. A check of Agency records and discussions with various individuals (RID mathematicians and persons who might have had contact with Rand Corp.) within the Agency has uncovered nothing concerning the system. This correspondence requests a description of the machine. In 1950 Mr. Nash submitted material, in interview, which was evaluated by NSA as not suitable. Serial: 2 3 6 1 2 JAN 1~5" • John a.sh Department of Mathematics…

Why was this case declassified?

This material entered the public record through the U.S. declassification and Freedom of Information Act (FOIA) process.

John Forbes Nash, Jr. Letters, National Security Agency

◆ BLUF — The short version

Document Title: John Forbes Nash, Jr. pdf The National Security Agency released a collection of letters exchanged between the agency and mathematician John Forbes Nash, Jr. in the 1950s. These letters are notable for their discussion of cryptography and Nash's proposed enciphering-deciphering machine.

Date: JUL 6 · 2026
Release: Declassified · U.S. public record (FOIA)

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Document Title: John Forbes Nash, Jr. Letters, National Security Agency Release Date: 2015-02-24 The Black Vault Entry: https://www.theblackvault.com/documentarchive/john-forbes-nash-jr-letters-national-security-agency/ Canonical PDF…

Questions about this case

What was John Forbes Nash, Jr. Letters, National Security Agency about?: Document Title: John Forbes Nash, Jr. pdf The National Security Agency released a collection of letters exchanged between the agency and mathematician John Forbes Nash, Jr. in the 1950s. These letters are notable for their discussion of cryptography and Nash's proposed enciphering-deciphering machine.
Why was this case declassified?: This material entered the public record through the U.S. declassification and Freedom of Information Act (FOIA) process. Storyflo narrates it directly from the public release.

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