The Chaocipher Clearing House

Progress Report #17

Moshe Rubin (

Chaocipher Revealed: The algorithm is publicly explained for the first time

This is it: we've reached the endgame.

Ninety-two years after its invention, and fifty-seven years after challenge messages were published, John F. Byrne's Chaocipher algorithm can finally be revealed.  The cryptologic community can now examine this tantalizing cipher, which eluded solution all these years, only this time with the knowledge of how it works.

The story of how and why Chaocipher came to be revealed can be read in Progress Report #16.  With no further ado, you can now read the document entitled "Chaocipher Revealed: The Algorithm".

In the next few days we hope to upload papers detailing how the exhibits in Byrne's autobiographical "Silent Years" were enciphered.  These will hopefully be followed by papers by other researchers on such topics as assessing the Chaocipher's cryptographic security, cryptanalysis of Chaocipher messages, the mechanical description of  Chaocipher, Byrne's proposed key distribution method, and more.

The Chaocipher Clearning House invites all students of cryptography to submit Chaocipher-related papers for inclusion on this web site.

Copyright (c) 2010 Moshe Rubin
Created: 2 July 2010
Updated: 18 January 2013

Return to the home page