Talk:Book cipher

message: I just added a citation from which I noticed several sentences of the article were direct quotes. I don't know enough about editing articles to know what to do about that, though. (27 Feb 2013)  — Preceding unsigned comment added by 205.185.110.8 (talk) 03:48, 28 February 2013 (UTC)
thread_title: Untitled

message: Why is it called an Ottendorf cipher? TuckerResearch (talk) 21:07, 9 November 2008 (UTC)
replies: text: Is Ottendorf cipher a synonym for book cipher, or more specific? —Tamfang (talk) 07:25, 13 January 2010 (UTC)
replies: text: Another question: why is "Ottendorf cipher" mentioned in the fiction section with no previous mention or any explanation...?  TREKphiler any time you're ready, Uhura  15:47, 13 April 2011 (UTC)

text: So far as I can tell, there is no reason to believe the book cipher was ever called an Ottendorf Cipher before its use in National Treasure. For example, David Kahn's encyclopedic https://en.wikipedia.org/wiki/The_Codebreakers does not use the term, and Ottendorf is not referenced in the book. This is true of all other crypto texts and histories at my disposal. I'm pretty sure I said all this in my interview for the National Treasure DVD, but I find my copy of the DVD doesn't include the interview. In any case, "citation required" (at least) is appropriate for this use of "Ottendorf". I concur with Lord Kryten's comments on 1 March 2012 that it's credible Ottendorf would have known about this type of cipher, but a 2004 movie script reference isn't an adequate basis for Wikipedia. Scryer~enwiki (talk) 03:06, 4 June 2022 (UTC)
replies: text: I found the National Treasure interviews online: https://www.youtube.com/watch?v=XGz4BlHdxJw . Interesting info especially from David Kahn, but the specific comments about the Ottendorf name were cut. Scryer~enwiki (talk) 03:38, 4 June 2022 (UTC)
thread_title:  Ottendorf cipher 

message: An Ottendorf cipher is used in The Protector's War by S. M. Stirling, although the author refers to it as an "Altendorf substition code."
--Gaarmyvet (talk) 22:07, 1 December 2010 (UTC)
thread_title:  The Protector's War 

message: Am I the only one concerned at the statement Japan was unable to break the Sorge book cipher? It leaves a false impression of the strength of this schoolboy method IMO, since the Japanese were notoriously bad at cryptanalysis. (They couldn't even break the simple cypher JFK used after his boat was run down! And no, I don't recall where I read it. Kahn?)  TREKphiler any time you're ready, Uhura  15:52, 13 April 2011 (UTC)
replies: text: It is quite possible they weren't able to break it -- but it wasn't a book cipher. Sorge's group used a sophisticated variant of the "Nihilist cipher". This incorporated a running key cipher (not a book cipher) for the 2nd of 3 stages. The running key was derived from a high entropy source; in combination with the modest compression provided in the first stage, this generated a ciphertext with a very high unicity distance. In other words, this was not a schoolboy method; it was exceptionally strong for a "pencil and paper" cipher. -- 202.63.39.58 (talk) 16:12, 24 September 2012 (UTC)
thread_title:  ''Domo arigato'', Sorge-''sama'' 

message: In John Le Carre's A Perfect Spy, the protagonist Magnus Pym uses a book cipher based on the German text Simplicissimus.Williamsonday (talk) 16:34, 21 January 2012 (UTC)
thread_title:  John Le Carre, A Perfect Spy 

message: "It is still susceptible to other methods of cryptanalysis, and as such is quite easily broken, even without sophisticated means, without the cryptanalist having any idea what book the cipher is keyed to."  My understanding of book codes is that they are quite difficult to break without the codebook, nearly on the level of one-time pads, in fact. I cannot find an example of a book code being broken without knowledge of the book. If the article is correct it should be expounded upon, and if it cannot be sourced, it should be deleted. [Macossay 13 June 2013]  — Preceding unsigned comment added by 209.137.134.50 (talk) 14:52, 13 June 2013 (UTC)
replies: text: I'm pretty sure that statement is incorrect. Without any knowledge of the key text at all, partial solutions would only be helpful if indexes are re-used or sufficiently close together that you could use them to also make guesses about the contents of the key text. I'm tempted to just delete it, but the book he/she cited looks interesting, so maybe I'll check it out first :) ExcitingBore (talk) 18:15, 9 February 2015 (UTC)
thread_title:  Security 

message: It is quite possible they weren't able to break it -- but it wasn't a book cipher. From 2012, still not changed.
The article correctly notes that using a dictionary creates a one part code, but does not use that term. 
I suggest the reader is referred to the Wikipedia article, Code(cryptography), where there is a clear description.
Book "ciphers" have been broken without possession of the book. In at least one case the decrypts were numerous and helpful. So helpful 
that the cryptanalyst, Elizebeth Smith, was able to find the actual volume after a brief search in a local library. This is described by 
Khan, The Codebreakers, on pp 371,372 revised edition 1996. AnnaComnemna (talk) 19:05, 9 May 2015 (UTC)
thread_title:  Sorge  etc. 

message: From at 100,000 foot perspective:  Why not update the book cipher for the 21st century, buy expanding the definition of a book to be any binary stream of data one can replicate at least twice (for en and de)?  This "Internet book" wouldn't be a book (as one defines it today - electronic or paper), but a stream of data from various Internet sources (e.g. photos on Flickr, web pages from the Wayback Machine, etc).  Of course, the method used to create this book and its source would have to be reproducible at least twice (en and de).
--Bmoshier (talk) 02:41, 31 December 2016 (UTC)
replies: text: If using the internet, why go through the trouble for this and not use a route with more entropy like SHA256?  Either way the recipient must have or be able to reproduce the key.205.142.232.18 (talk) 21:36, 10 August 2017 (UTC)
thread_title:  Look at the Internet as a book