finding key of vigenere

urgently need help!

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finding key of vigenere

Posted 31 January 2010 - 03:57 AM

i am currently trying to do a programme to decrypt vigenere cipher where i need to try to find key length of a vigenere cipher whereby first i need to split the encrypted text into the different parts and calculate the index of coincidence of each text by using the formula (a*(a-1))/(n*(n-1)). the a in the formula is the occurrence of any letter in each text and n is the total number of letter in the text. but now when i split the text into 6 parts and to calculate the index of coincidence of each part i've got a weird answer on the third answer.

after calculating what i should be getting is 0.0xxx which is shown in ic[0] and ic[1] and the error seems to start on counter2. can any kind soul help on this? thanks

due to my long codes i could not display it here therefore i have added an attachment

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This post has been edited by complexity: 31 January 2010 - 04:27 AM

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