The Chaocipher Clearing House

Cover Letter in Response to FOIA Request

Moshe Rubin (

In March 2009 I requested information from NSA pertaining to the Chaocipher under the Freedom of Information Act.  In April 2009 I received the following two page cover letter in reply.

Cover letter page 1
Cover letter page 2

Following are links to the eleven (11) pages of John F. Byrne's "Chaocipher -- The Ultimate Elusion" (1937) I received from NSA.

Page Comments
1 Handwritten dedication from John F. Byrne to Rosario Candela; Byrne's handwritten explanations, correction of a typo; NSA declassification stamp from 20 September 2005.
10 Carries some of Rosario Candela's underlinings a pair of digraphs ("DC") and trigraphs ("SOT").
10 (b) This is a second photocopy of page 10, with the apparent plaintext to the last  17 ciphertext letters in Exhibit 1.  It is not clear if this page came from Rosario Candela's collection, nor on what authority this plaintext is based.

Copyright (c) 2009 Moshe Rubin
Created: 16 April 2009

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