Data commit

Task/Chaocipher/Groovy/chaocipher.groovy

@@ -0,0 +1,79 @@
+class Chaocipher {
+    private enum Mode {
+        ENCRYPT,
+        DECRYPT
+    }
+
+    private static final String L_ALPHABET = "HXUCZVAMDSLKPEFJRIGTWOBNYQ"
+    private static final String R_ALPHABET = "PTLNBQDEOYSFAVZKGJRIHWXUMC"
+
+    private static int indexOf(char[] a, char c) {
+        for (int i = 0; i < a.length; ++i) {
+            if (a[i] == c) {
+                return i
+            }
+        }
+        return -1
+    }
+
+    private static String exec(String text, Mode mode) {
+        return exec(text, mode, false)
+    }
+
+    private static String exec(String text, Mode mode, Boolean showSteps) {
+        char[] left = L_ALPHABET.toCharArray()
+        char[] right = R_ALPHABET.toCharArray()
+        char[] eText = new char[text.length()]
+        char[] temp = new char[26]
+
+        for (int i = 0; i < text.length(); ++i) {
+            if (showSteps) {
+                println("${new String(left)}  ${new String(right)}")
+            }
+            int index
+            if (mode == Mode.ENCRYPT) {
+                index = indexOf(right, text.charAt(i))
+                eText[i] = left[index]
+            } else {
+                index = indexOf(left, text.charAt(i))
+                eText[i] = right[index]
+            }
+            if (i == text.length() - 1) {
+                break
+            }
+
+            // permute left
+
+            if (26 - index >= 0) System.arraycopy(left, index, temp, 0, 26 - index)
+            System.arraycopy(left, 0, temp, 26 - index, index)
+            char store = temp[1]
+            System.arraycopy(temp, 2, temp, 1, 12)
+            temp[13] = store
+            left = Arrays.copyOf(temp, temp.length)
+
+            // permute right
+
+            if (26 - index >= 0) System.arraycopy(right, index, temp, 0, 26 - index)
+            System.arraycopy(right, 0, temp, 26 - index, index)
+            store = temp[0]
+            System.arraycopy(temp, 1, temp, 0, 25)
+            temp[25] = store
+            store = temp[2]
+            System.arraycopy(temp, 3, temp, 2, 11)
+            temp[13] = store
+            right = Arrays.copyOf(temp, temp.length)
+        }
+
+        return new String(eText)
+    }
+
+    static void main(String[] args) {
+        String plainText = "WELLDONEISBETTERTHANWELLSAID"
+        println("The original plaintext is : $plainText")
+        println("\nThe left and right alphabets after each permutation during encryption are:")
+        String cipherText = exec(plainText, Mode.ENCRYPT, true)
+        println("\nThe cipher text is : $cipherText")
+        String plainText2 = exec(cipherText, Mode.DECRYPT)
+        println("\nThe recovered plaintext is : $plainText2")
+    }
+}