Talk:Vigenère cipher

message: "Vigenère"?
Also, the Vigenère table shown is interesting because of its selective use of borders.  It only has borders where they matter, unlike 90% of Wikipedia tables which look like ugly grid messes.
:I don't know IPA but it is roughly pronounced "vi-je-nair". Also that table is an image not a table, that's why it look different. BrokenSegue 04:24, 22 February 2006 (UTC)
thread_title:  pronunciation? 

message: The History section of this article need lots of cleanup and expansion. I don't really have the time now, but the book "Khan on Codes" would be a good source. Suspender guy (talk) 14:07, 21 March 2017 (UTC)
replies: text: Neat!  Thanks for the exposition.  Lunkwill 06:16, 15 June 2006 (UTC)
thread_title:  '''Historical Notes''' 

message: The French word for unbreakable is "incassable" according to my French volumes.  Casser (to break) is the root, as in "casse-tete", for "break-head" which is used sometimes to describe puzzles.
"Le chiffre indéchiffrable" translates directly as "the indecipherable cipher," since the root of "indéchiffrable" is "chiffre."  I haven't changed this since I may not know the precedent for using the "unbreakable" translation.--WPaulB 02:32, 3 March 2007 (UTC)
replies: text: yeah, I agree undecipherable seems more correct, but for a cipher what's the difference between unbreakable and undecipherable? BrokenSegue 23:43, 10 June 2007 (UTC)

text: We want to use an idiomatic translation, to capture the meaning.  In current American English usage, "undecipherable" could connote "illegible" or "incorrectly enciphered" as well as "unbreakable".  I think "unbreakable" captures the intent more precisely. — DAGwyn 20:23, 13 June 2007 (UTC)
thread_title:  Translation 

message: sorry to intervene this neat todo-list, but I have something to say (I'm not a skilled/trained/experienced wikipedia-contributor, so i don't know how to put this right :P):
the picture of "The Vigenère square or Vigenère table" overlaps the paragraph left of it, speaking of 26! possibilites and so on. screen-resolution:1280x1024. using firefox.
:Doesn't do that for me... Don't know why it would break like that. BrokenSegue 23:44, 10 June 2007 (UTC)
replies: text: It seems okay under Firefox 2.0.0.3 on Solaris.  Perhaps you have a PNG viewer enabled that mispositions images? — DAGwyn 20:19, 13 June 2007 (UTC)

text: I get this error too. Firefox 2.0.0.6 on Kubuntu. Perhaps it is a font thing. That often messes up layouts. 86.154.82.20 00:52, 24 August 2007 (UTC)
thread_title:  comments 

message: What are people's views on adding the likely reason for Babbage not publishing his method, i.e. that he had contacts with the government of the day and may have been asked not to publish?  This is mentioned in the Simon Singh book already referenced (albeit in the English edition entitled "The Science of Secrecy"). --TraceyR 17:56, 6 September 2007 (UTC)
replies: text: It appears to be pure speculation on Singh's part, therefore not something worth reporting in an encyclopedia.  I note that Singh has definitely got several other things wrong in his book. — DAGwyn 06:09, 7 September 2007 (UTC)
thread_title:  Babbage: possible reason for not publishing his method 

message: :From the article:
:This cipher is well known because while it is easy to understand and implement, it often appears to beginners to be unbreakable; this earned it the description le chiffre indéchiffrable (French for 'the unbreakable cipher'). Consequently, many people have tried to implement obfuscation or encryption schemes that are essentially Vigenère ciphers, only to have them broken[1]
The way I interpret this paragraph is that BECAUSE the Vingenere cipher was thought to be unbreakable, folks went out and wrote their own schemes that were (a) sometimes obfuscation so not even related to Vingenere Cipher and (b) ciphers that were based on the same principal as Vingerere and shared the weakness.  Certainly (a) does not follow.  And I don't believe the reference [1] would make that statement, but it could be illogical also ;-)  —Preceding unsigned comment added by 24.99.85.51 (talk) 05:42, 24 January 2008 (UTC)
replies: text: I fixed the sentence.  Obfuscation isn't relevant and merely, um, obfuscates the issue. — DAGwyn (talk) 21:29, 24 January 2008 (UTC)
thread_title:  Consequently?? 

message: Test was invented in 1920, not in 1925, according to http://www.nsa.gov/cch/cch00005.cfm.
It should be changed, I think. I'm not sure, because there are other sources with 1922.
My native language is Serbian, and I'll put 1920. on sr.wikipedia.
Senior-sr (talk) 13:06, 30 January 2008 (UTC)
replies: text: The kappa test is just a simple application of the index of coincidence, and probably evolved over some period of time.  I changed the article to say "in the 1920s". — DAGwyn (talk) 19:20, 30 January 2008 (UTC)
thread_title:  Friedman test 

message: Does speculation suddenly become not speculation, simply because we've cited who was speculating?  Singh offers no evidence as to why Babbage did not publish, he simply states a possibility.  It seems equally likely, to me, that Babbage did not publish because he was not the discoverer.  
Franksen offers the only detailed examination of Babbage's cryptographic notes that I've found.  And he finds nothing to indicate that Babbage had invented Kasiski's method. He says that Babbage's notes simply showing him using Kasiski's method - and Kerckhoff's (which I notice we do not credit Babbage for) - in a purely matter-of-fact way.  Were these attacks generally known, among the cognoscenti, long before they were published?
I've often wondered whether the Vig actually had the reputation for unbreakability that is so often claimed for it - among the pros, at least.  Vigenere's own offerings were, after all, variations that would have defeated the Kasiski examination.  Was he aware of the attack, that long ago?  If it really was unbreakable, why did no one use it?
But my speculations in this area have no more business being in the article than do Singh's.  Speculation is cheap and easy.  It provides topics of conversation, no more.
--jdege (talk) 23:05, 10 August 2009 (UTC)
thread_title:  Speculation? 

message: Something that might belong in this article is some reference to the probable word attack.  There is an article discussing this in Aegean Park's "Cyptography and Cryptanalysis Articles: Volume I".  As an attack against the Vig and other periodic polyalphabetics, it's less often successful than the Kasiski, but then the Kasiski is less often successful than the Vig, so that doesn't mean it's not worth a mention.
The probable word attack predates the Kasiski by quite a bit.  There is an example of using the probable word method to attack a Gronsfeld cipher in William Blair's article "Cipher", from Abraham Rees' "Cyclopedia", published in 1807.  (Jules Verne describes the decryption of a Gronsfeld in his 1881 novel "La Jangada", and my guess is that technique came from Blair's Cyclopedia article, but that's just speculation, again.)
--jdege (talk) 23:05, 10 August 2009 (UTC)
replies: text: Probable-text is just a general tactic used as part of cryptanalysis against many systems; it is not Vigenère-specific. In fact, in doesn't help much at all against this system when mixed alphabets are used in the tableau. — DAGwyn (talk) 20:43, 16 February 2015 (UTC)
thread_title:  Probable Word Attack 

message: The example given in the Kasiski examination section only works because of the number of letter between the recurring word (CYPHER). If that wouldn't happen to be a multiple of the recurring word the whole example would fail.
While the Kasiski method may work with longer texts and frequent occurrences, the example given is extremely misleading (in addition to it not working with the given spaces - which I've removed already).
I would suggest to drop this example altogether, or find one that gets this point across better. 69.196.191.24 (talk) 12:55, 8 July 2010 (UTC)
replies: text: I can't see any CYPHER anywhere, you presumably mean CRYPTO. That has length 6, and the gap between its two occurrences has length 10, which is not a multiple of 6, hence what you say does not make much sense to me. The reason, and the only reason, why the example works, is that 16 is a multiple of the key length (4), as explained in the text, and that's exactly the point the example is trying to get across.—Emil J. 13:17, 8 July 2010 (UTC)
replies: text: Yes, the method is valid, and indeed not 'every' repetition provides an entry, just those that happen to have starting locations that differ by a multiple of the key size. — DAGwyn (talk) 22:20, 23 July 2010 (UTC)
thread_title:  Kasiski examination example doesn't make any sense 

message: The Algebraic description in the current version only makes sense if the key is as long as the message, i.e. n <= m. This should be corrected —157.161.190.9 (talk) 09:09, 15 December 2014 (UTC)
replies: text: Fixed. —DAGwyn (talk) 20:55, 16 February 2015 (UTC)
thread_title:  Algebraic description 

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