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@@ -135,15 +135,15 @@ Functions</h2></td></tr>
<p>The Vigenère cipher is a method of encrypting alphabetic text by using a series of interwoven vigenere ciphers, based on the letters of a keyword. It employs a form of polyalphabetic substitution.</p>
<h3><a class="anchor" id="autotoc_md1"></a>
Algorithm</h3>
<p>The encryption can also be represented using modular arithmetic by first transforming the letters into numbers, according to the scheme, A → 0, B → 1, ..., Z → 25. Encryption of \(\i^{th}\) character in Message M by key K can be described mathematically as,</p>
<p>The encryption can also be represented using modular arithmetic by first transforming the letters into numbers, according to the scheme, A → 0, B → 1, ..., Z → 25. Encryption of \(i^{th}\) character in Message M by key K can be described mathematically as,</p>
<p class="formulaDsp">
\[ E_{K}(M_{i}) = (M_{i} + K_{i})\;\mbox{mod}\; 26\]
</p>
<p>while decryption of \(\i^{th}\) character in Cipher C by key K can be described mathematically as,</p>
<p>while decryption of \(i^{th}\) character in Cipher C by key K can be described mathematically as,</p>
<p class="formulaDsp">
\[ D_{k}(C_{i}) = (C_{i} - K_{i} + 26)\;\mbox{mod}\; 26\]
</p>
<p>Where \(\K_{i}\) denotes corresponding character in key. If \(\|key| &lt; |text|\) than same key is repeated untill their lengths are equal.</p>
<p>Where \(K_{i}\) denotes corresponding character in key. If \(|key| &lt; |text|\) than same key is repeated untill their lengths are equal.</p>
<p>For Example, If M = "ATTACKATDAWN" and K = "LEMON" than K becomes "LEMONLEMONLE".</p>
<dl class="section note"><dt>Note</dt><dd>Rather than creating new key of equal length this program does this by using modular index for key (i.e. \((j + 1) \;\mbox{mod}\; |\mbox{key}|\))</dd>
<dd>