Talk:Autokey cipher

message: This article has no information on how the cypher was broken. ✏ Sverdrup 02:28, 21 Nov 2004 (UTC)

message: I am a little bit confused: is Vigenere autokey cipher self-synchronizing? --Necago 16:38, 9 June 2007 (UTC)
replies: text: Yes, the Vigenere autokey cipher is a  self-synchronizing stream cipher. How can we make this article less confusing? --DavidCary (talk) 15:32, 26 March 2016 (UTC)

text: Whoops, my mistake. The discussion at "Why is Vigenère Autokey self-synchronizing?" has convinced me that the traditional Vigenere autokey cipher with an n-character primer key does not self-recover after getting out of sync -- an error during transmission changing one ciphertext character will propagate during decoding into every n-th following plaintext letter. An error inserting or deleting a character is even worse. So it is not a self-synchronizing cipher. Sorry, Necago! --DavidCary (talk) 23:17, 25 February 2021 (UTC)
thread_title:  Self-synchronizing 

message: For all you cryptanalysts out there, you should know that if you have computer, and your given just the ciphertext, you can brute force the key by attacking each key letter individually. So let's say I've been given a long autokey cipher. Given a keylength, or a number out of a list of keylengths to try, each letter of the key can be found by deciphering each letter of the cipher that that key decrypts. I can try the letter 'a', see how close the frequency analysis of the decrypted characters is to normal frequency analysis, try 'b', see if the frequency analysis is closer than 'a', and so on. For a computer, this takes a few seconds, and is easier than the cryptanalysis shown in the article. Hope this helps any future programmer, Jessemv (talk) 00:26, 24 November 2009 (UTC)
replies: text: This is likely original research unless someone else has had this idea in the past, I think there is perhaps a more efficient and reliable solution to the method of brute forcing an Autokey Cipher. Instead of doing frequency analysis comparisons on the plaintext that a particular key character decrypts to, do the frequency analysis over all the characters that have been found using the detected key. For example, if I try for a key length of 3, and for the first character I run through A-Z and find that 'c' makes the best plaintext frequency analysis, I then repeat this to find the next character in the key, but using the 'c' character as well. Eventually I might find that 'ca' makes the best frequency analysis, and the final character 't' makes it even better. Key = 'cat' Jessemv (talk) 00:36, 25 November 2009 (UTC)
thread_title:  Brute-forcing the key 

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thread_title:  External links modified