Merge pull request #317 from aryabharat/master

Create AtBash.js

Ciphers/Atbash.js

@@ -0,0 +1,29 @@
+/*
+The Atbash cipher is a particular type of monoalphabetic cipher
+formed by taking the alphabet and mapping it to its reverse,
+so that the first letter becomes the last letter,
+the second letter becomes the second to last letter, and so on.
+*/
+
+/**
+ * Decrypt a Atbash cipher
+ * @param {String} str - string to be decrypted/encrypt
+ * @return {String} decrypted/encrypted string
+ */
+function Atbash (message) {
+  let decodedString = ''
+  for (let i = 0; i < message.length; i++) {
+    if (/[^a-zA-Z]/.test(message[i])) {
+      decodedString += message[i]
+    } else if (message[i] === message[i].toUpperCase()) {
+      decodedString += String.fromCharCode(90 + 65 - message.charCodeAt(i))
+    } else {
+      decodedString += String.fromCharCode(122 + 97 - message.charCodeAt(i))
+    }
+  }
+  return decodedString
+}
+// Atbash Example
+const encryptedString = 'HELLO WORLD'
+const decryptedString = Atbash(encryptedString)
+console.log(decryptedString) // SVOOL DLIOW