Re: [NEWBIE]vigenere
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Re: [NEWBIE]vigenere

From: Sebastian Gottschalk <seppi@seppig.de>
Date: Fri Jan 13 2006 - 16:48:10 CET



cicap wrote:


> How can I give a proof that Vigenere is not perfect, using Shannon theory?



Very simply. A perfect cipher is isomorph to addition within a group,


hence One Time Pad.



> For example with a key length of 4,  against a plain text of  8 characters. 



4 < 8


q.e.d.


Received on Tue Jan 17 16:50:16 2006