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The idea is that you perform a frequency analysis for each of the letters of the keyword. So, if you have determined how long the key is, you can identify each letter of the key separately.<br />
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It's nicely described here :<br />
<br />
&nbsp; &nbsp; &nbsp; &nbsp; <a href="http://www.simonsingh.net/The_Black_Chamber/vigenere_cracking.html" rel="ugc">http://www.simonsingh.net/The_Black_Chamber/vigenere_cracking.html</a><br />
<br />
(specifically the cracking example)
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The idea is that you perform a frequency analysis for each of the letters of the keyword. So, if you have determined how long the key is, you can identify each letter of the key separately.

It's nicely described here :

        http://www.simonsingh.net/The_Black_Chamber/vigenere_cracking.html [http://www.simonsingh.net/The_Black_Chamber/vigenere_cracking.html]

(specifically the cracking example)

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I want to write a program to break vigenere cipher. I understand the logic how it is encrypted and decrypted. I want to find the key. By using IC and Kasiski method, I am able to find the key length. But after that how do I programmically find the key? I just need to know what is the logic or math formula to do it... Any clues?
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</div>


I want to write a program to break vigenere cipher. I understand the logic how it is encrypted and decrypted. I want to find the key. By using IC and Kasiski method, I am able to find the key length. But after that how do I programmically find the key? I just need to know what is the logic or math formula to do it... Any clues?

Breaking vigenere cipher

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Security is the protection of information systems from theft or damage to the hardware, the software, and the information on them, as well as from disruption or misdirection of the services they provide. The main goal of security is protecting assets, and an asset is anything of value and worthy of protection.  Information Security is a discipline of protecting information assets from threats through safeguards to achieve the objectives of confidentiality, integrity, and availability or CIA for short. On the other hand, disclosure, alteration, and disruption (DAD) compromise the security objectives.

Security

Puzzles and riddles are statements and questions framed such that they require ingenuity and imagination to resolve. Most are mathematical conundrums, but can also include the arcane, trivial or simply funny.