Data update

Task/Chaocipher/Swift/chaocipher.swift

@@ -0,0 +1,84 @@
+enum Mode {
+    case encrypt
+    case decrypt
+}
+
+class Chaocipher {
+    private static let L_ALPHABET = "HXUCZVAMDSLKPEFJRIGTWOBNYQ"
+    private static let R_ALPHABET = "PTLNBQDEOYSFAVZKGJRIHWXUMC"
+
+    private static func indexOf(array: [Character], char: Character) -> Int {
+        for i in 0..<array.count {
+            if array[i] == char {
+                return i
+            }
+        }
+        return -1
+    }
+
+    private static func exec(text: String, mode: Mode, showSteps: Bool = false) -> String {
+        var left = Array(L_ALPHABET)
+        var right = Array(R_ALPHABET)
+        var eText = [Character](repeating: " ", count: text.count)
+        var temp = [Character](repeating: " ", count: 26)
+
+        let textChars = Array(text)
+
+        for i in 0..<text.count {
+            if showSteps {
+                print("\(String(left))  \(String(right))")
+            }
+
+            let index: Int
+            if mode == .encrypt {
+                index = indexOf(array: right, char: textChars[i])
+                eText[i] = left[index]
+            } else {
+                index = indexOf(array: left, char: textChars[i])
+                eText[i] = right[index]
+            }
+
+            if i == text.count - 1 {
+                break
+            }
+
+            // permute left
+            temp[0..<(26-index)] = left[index..<26]
+            temp[(26-index)..<26] = left[0..<index]
+            let store = temp[1]
+            temp[1..<13] = temp[2..<14]
+            temp[13] = store
+            left = temp
+
+            // permute right
+            temp[0..<(26-index)] = right[index..<26]
+            temp[(26-index)..<26] = right[0..<index]
+            let store1 = temp[0]
+            temp[0..<25] = temp[1..<26]
+            temp[25] = store1
+            let store2 = temp[2]
+            temp[2..<13] = temp[3..<14]
+            temp[13] = store2
+            right = temp
+        }
+
+        return String(eText)
+    }
+
+    static func encrypt(text: String, showSteps: Bool = false) -> String {
+        return exec(text: text, mode: .encrypt, showSteps: showSteps)
+    }
+
+    static func decrypt(text: String, showSteps: Bool = false) -> String {
+        return exec(text: text, mode: .decrypt, showSteps: showSteps)
+    }
+}
+
+// Main program
+let plainText = "WELLDONEISBETTERTHANWELLSAID"
+print("The original plaintext is : \(plainText)")
+print("\nThe left and right alphabets after each permutation during encryption are:")
+let cipherText = Chaocipher.encrypt(text: plainText, showSteps: true)
+print("\nThe cipher text is : \(cipherText)")
+let plainText2 = Chaocipher.decrypt(text: cipherText)
+print("\nThe recovered plaintext is : \(plainText2)")