Added an XOR cipher (#135)

* Added an XOR cipher

* Rename xor_cipher.js to XORCipher.js

* Update XORCipher.js

Co-authored-by: vinayak <itssvinayak@gmail.com>

Ciphers/XORCipher.js

@@ -0,0 +1,26 @@
+/**
+ * The XOR cipher is a type of additive cipher.
+ * Each character is bitwise XORed with the key.
+ * We loop through the input string, XORing each
+ * character with the key.
+ */
+
+/**
+ * Encrypt using an XOR cipher
+ * @param {String} str - String to be encrypted
+ * @param {Number} key - key for encryption
+ * @return {String} encrypted string
+ */
+
+function XOR (str, key) {
+  let result = ''
+  for (const elem of str) {
+    result += String.fromCharCode(elem.charCodeAt(0) ^ key)
+  }
+  return result
+}
+
+const encryptedString = XOR('test string', 32)
+console.log('Encrypted: ', encryptedString)
+const decryptedString = XOR(encryptedString, 32)
+console.log('Decrypted: ', decryptedString)