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 18.104.22.168 (talk) 03:48, 28 February 2013 (UTC)
A book cipher appears in the new movie, National Treasure (under a title I didn't quite catch, something like "Andorf cipher"). The key is Benjamin Franklin's Silence Dogood letters. In case it attracts people's attention, we may want to flesh out this article a bit. (The movie also features invisible inks, though oddly uses lemon juice the developer). Securiger 19:43, 27 Nov 2004 (UTC)
- Is Ottendorf cipher a synonym for book cipher, or more specific? —Tamfang (talk) 07:25, 13 January 2010 (UTC)
Authors of American fiction seem to use the description 'Ottendorf Cipher' in a relaxed manner (see entries for 'Lost' and that... movie) but I have as yet been unable to find a definition. I'm assuming the name comes from Major Nicholas Dietrich, Baron de Ottendorf who was a German mercenary at the time of the American Revolution and ended up working for the British (commanded by Clinton) organising spies in the French and American camps. Ottenddorf worked for Major André of Benedict Arnold fame (see Arnold Cipher) and controlled at least one documented spy, the mysterious Miss Jenny (refer Clements Library). Both Clinton and André regularly used book ciphers of one form or another to exchange information with their agents and it is reasonable to assume Ottendorf did also, although I have seen no evidence to say he did. So the question remains, what is an Ottendorf cipher? Lord Kryten (talk) 01:15, 1 March 2012 (UTC)
Presumption of Death
The link goes to the legal usage, rather than the novel which it obviously should.
The Protector's War
Domo arigato, Sorge-sama
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)
- 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. -- 22.214.171.124 (talk) 16:12, 24 September 2012 (UTC)
John Le Carre, A Perfect Spy
"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 126.96.36.199 (talk) 14:52, 13 June 2013 (UTC)
- 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)
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) No comments or objections. I have removed the comment that Sorge used a book cipher. AnnaComnemna (talk) 14:27, 2 June 2015 (UTC)