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1/10/24--VigenereCipher
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2 changed files with 30 additions and 40 deletions
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@ -38,32 +38,29 @@ class VigenèreDecode extends Operation {
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* @returns {string}
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*/
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run(input, args) {
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const alphabet = "abcdefghijklmnopqrstuvwxyz",
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const alphabet = "abcdefghijklmnopqrstuvwxyz0123456789",
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key = args[0].toLowerCase();
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let output = "",
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fail = 0,
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keyIndex,
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msgIndex,
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chr;
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let output = "";
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let fail = 0;
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let keyIndex,msgIndex,chr;
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if (!key) throw new OperationError("No key entered");
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if (!/^[a-zA-Z]+$/.test(key)) throw new OperationError("The key must consist only of letters");
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if (!/^[a-zA-Z0-9]+$/.test(key)) throw new OperationError("The key must consist only of letters and numbers");
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for (let i = 0; i < input.length; i++) {
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if (alphabet.indexOf(input[i]) >= 0) {
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const currentChar = input[i];
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const lowerChar = currentChar.toLowerCase();
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//Implementing logic
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if (alphabet.indexOf(lowerChar) >= 0) {
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chr = key[(i - fail) % key.length];
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keyIndex = alphabet.indexOf(chr);
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msgIndex = alphabet.indexOf(input[i]);
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// Subtract indexes from each other, add 26 just in case the value is negative,
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// modulo to remove if necessary
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output += alphabet[(msgIndex - keyIndex + alphabet.length) % 26];
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} else if (alphabet.indexOf(input[i].toLowerCase()) >= 0) {
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chr = key[(i - fail) % key.length].toLowerCase();
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keyIndex = alphabet.indexOf(chr);
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msgIndex = alphabet.indexOf(input[i].toLowerCase());
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output += alphabet[(msgIndex + alphabet.length - keyIndex) % 26].toUpperCase();
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msgIndex = alphabet.indexOf(lowerChar);
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// Decode character using the Vigenère formula
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const decodedChar = alphabet[(msgIndex - keyIndex + alphabet.length) % alphabet.length];
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// Preserve case for letters and add to output
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output += currentChar === lowerChar ? decodedChar : decodedChar.toUpperCase();
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} else {
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output += input[i];
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output += currentChar; // Keep non-alphabetic characters as is
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fail++;
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}
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}
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@ -39,36 +39,29 @@ class VigenèreEncode extends Operation {
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* @returns {string}
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*/
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run(input, args) {
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const alphabet = "abcdefghijklmnopqrstuvwxyz",
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const alphabet = "abcdefghijklmnopqrstuvwxyz0123456789",
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key = args[0].toLowerCase();
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let output = "",
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fail = 0,
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keyIndex,
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msgIndex,
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chr;
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let output = "";
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let fail = 0;
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let keyIndex, msgIndex, chr;
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if (!key) throw new OperationError("No key entered");
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if (!/^[a-zA-Z]+$/.test(key)) throw new OperationError("The key must consist only of letters");
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if (!/^[a-zA-Z0-9]+$/.test(key)) throw new OperationError("The key must consist only of letters and numbers");
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for (let i = 0; i < input.length; i++) {
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if (alphabet.indexOf(input[i]) >= 0) {
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// Get the corresponding character of key for the current letter, accounting
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// for chars not in alphabet
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const currentChar = input[i];
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const lowerChar = currentChar.toLowerCase();
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//Implementing logic
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if (alphabet.indexOf(lowerChar) >= 0) {
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// Get the corresponding character of key for the current letter
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chr = key[(i - fail) % key.length];
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// Get the location in the vigenere square of the key char
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keyIndex = alphabet.indexOf(chr);
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// Get the location in the vigenere square of the message char
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msgIndex = alphabet.indexOf(input[i]);
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// Get the encoded letter by finding the sum of indexes modulo 26 and finding
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// the letter corresponding to that
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output += alphabet[(keyIndex + msgIndex) % 26];
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} else if (alphabet.indexOf(input[i].toLowerCase()) >= 0) {
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chr = key[(i - fail) % key.length].toLowerCase();
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keyIndex = alphabet.indexOf(chr);
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msgIndex = alphabet.indexOf(input[i].toLowerCase());
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output += alphabet[(keyIndex + msgIndex) % 26].toUpperCase();
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msgIndex = alphabet.indexOf(lowerChar);
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const encodedChar = alphabet[(keyIndex + msgIndex) % alphabet.length];
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// Preserve case for letters
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output += currentChar === lowerChar ? encodedChar : encodedChar.toUpperCase();
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} else {
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output += input[i];
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output += currentChar; // Keep non-alphabetic characters as is
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fail++;
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}
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}
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