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The Chaocipher 〔(What is Chaocipher? ), The Chaocipher Clearing House, retrieved August 8, 2010〕 is a cipher method invented by J. F. Byrne in 1918 and described in his 1953 autobiographical ''Silent Years''.〔Byrne , J. F. 1953 . Silent Years: An Autobiography with Memoirs of James Joyce and Our Ireland . New York : Farrar, Straus, and Young (Reprinted in 1975 by Octagon Books, a division of Farrar, Straus, and Giroux).〕 He believed Chaocipher was simple, yet unbreakable. Byrne stated that the machine he used to encipher his messages could be fitted into a cigar box. He offered cash rewards for anyone who could solve it. In May 2010 the Byrne family donated all Chaocipher-related papers and artifacts〔(Chaocipher Machine and Papers ) National Cryptologic Museum, retrieved July 2, 2010〕 to the National Cryptologic Museum in Ft. Meade, Maryland, USA. This led to the disclosure of the Chaocipher algorithm. == How Chaocipher works == The Chaocipher system consists of two alphabets, with the "right" alphabet used for locating the plaintext letter while the other ("left") alphabet is used for reading the corresponding ciphertext letter. The underlying algorithm is related to the concept of dynamic substitution〔(Substitution Cipher with Pseudo-Random Shuffling: The Dynamic Substitution Combiner. ) Ritter, T. 1990. Cryptologia. 14(4): 289-303. Retrieved July 2, 2010〕 whereby the two alphabets are slightly modified after each input plaintext letter is enciphered. This leads to nonlinear and highly diffused alphabets as encryption progresses. Deciphering is identical to enciphering, with the ciphertext letter being located in the "left" alphabet while the corresponding plaintext letter being read from the "right" alphabet. A detailed description of the Chaocipher algorithm is available〔 as well as discussions of the deciphered plaintexts and the solution to Byrne's challenge. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Chaocipher」の詳細全文を読む スポンサード リンク
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