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Merge pull request #58 from jonathangomz/patch-1
Create vigenereCipher.js
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81
Ciphers/vigenereCipher.js
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81
Ciphers/vigenereCipher.js
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/**
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* Check if the Character is letter or not
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* @param {String} character - character to check
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* @return {object} An array with the character or null if isn't a letter
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*/
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function isLetter(str) {
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return str.length === 1 && str.match(/[a-zA-Z]/i);
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}
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/**
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* Check if is Uppercase or Lowercase
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* @param {String} character - character to check
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* @return {Boolean} result of the checking
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*/
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function isUpperCase(character){
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if (character == character.toUpperCase()) {
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return true;
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}
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if (character == character.toLowerCase()){
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return false;
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}
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}
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/**
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* Encrypt a Vigenere cipher
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* @param {String} message - string to be encrypted
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* @param {String} key - key for encrypt
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* @return {String} result - encrypted string
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*/
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function encrypt(message, key)
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{
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let result = "";
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for (let i = 0, j = 0; i < message.length; i++) {
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let c = message.charAt(i);
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if (isLetter(c)){
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if(isUpperCase(c)) {
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result += String.fromCharCode((c.charCodeAt(0) + key.toUpperCase().charCodeAt(j) - 2 * 65) % 26 + 65); // A: 65
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} else {
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result += String.fromCharCode((c.charCodeAt(0) + key.toLowerCase().charCodeAt(j) - 2 * 97) % 26 + 97); // a: 97
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}
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} else {
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result+=c;
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}
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j = ++j % key.length;
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}
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return result;
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}
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/**
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* Decrypt a Vigenere cipher
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* @param {String} message - string to be decrypted
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* @param {String} key - key for decrypt
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* @return {String} result - decrypted string
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*/
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function decrypt(message, key)
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{
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let result ="";
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for(let i = 0, j = 0; i < message.length; i++){
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let c = message.charAt(i);
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if (isLetter(c)){
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if(isUpperCase(c)) {
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result += String.fromCharCode(90-(25-(c.charCodeAt(0)-key.toUpperCase().charCodeAt(j)))%26);
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} else {
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result += String.fromCharCode(122-(25-(c.charCodeAt(0)-key.toLowerCase().charCodeAt(j)))%26);
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}
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} else {
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result+=c;
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}
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j = ++j % key.length;
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}
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return result;
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}
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let messageEncrypt = encrypt('Hello World!', 'code');
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console.log(messageEncrypt); // "Jhpnr Yrvng!"
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let messageDecrypt = decrypt('Jsopq Zstzg!', 'code');
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console.log(messageDecrypt); // "Hello World!"
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