Data commit

Task/Chaocipher/Kotlin/chaocipher.kotlin

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+// Version 1.2.40
+
+enum class Mode { ENCRYPT, DECRYPT }
+
+object Chao {
+    private val lAlphabet = "HXUCZVAMDSLKPEFJRIGTWOBNYQ"
+    private val rAlphabet = "PTLNBQDEOYSFAVZKGJRIHWXUMC"
+
+    fun exec(text: String, mode: Mode, showSteps: Boolean = false): String {
+        var left  = lAlphabet
+        var right = rAlphabet
+        val eText = CharArray(text.length)
+        val temp  = CharArray(26)
+
+        for (i in 0 until text.length) {
+            if (showSteps) println("$left  $right")
+            var index: Int
+            if (mode == Mode.ENCRYPT) {
+                index = right.indexOf(text[i])
+                eText[i] = left[index]
+            }
+            else {
+                index = left.indexOf(text[i])
+                eText[i] = right[index]
+            }
+            if (i == text.length - 1) break
+
+            // permute left
+
+            for (j in index..25) temp[j - index] = left[j]
+            for (j in 0 until index) temp[26 - index + j] = left[j]
+            var store = temp[1]
+            for (j in 2..13) temp[j - 1] = temp[j]
+            temp[13] = store
+            left = String(temp)
+
+            // permute right
+
+            for (j in index..25) temp[j - index] = right[j]
+            for (j in 0 until index) temp[26 - index + j] = right[j]
+            store = temp[0]
+            for (j in 1..25) temp[j - 1] = temp[j]
+            temp[25] = store
+            store = temp[2]
+            for (j in 3..13) temp[j - 1] = temp[j]
+            temp[13] = store
+            right = String(temp)
+        }
+
+        return String(eText)
+    }
+}
+
+fun main(args: Array<String>) {
+    val plainText = "WELLDONEISBETTERTHANWELLSAID"
+    println("The original plaintext is : $plainText")
+    println("\nThe left and right alphabets after each permutation" +
+             " during encryption are :\n")
+    val cipherText = Chao.exec(plainText, Mode.ENCRYPT, true)
+    println("\nThe ciphertext is : $cipherText")
+    val plainText2 = Chao.exec(cipherText, Mode.DECRYPT)
+    println("\nThe recovered plaintext is : $plainText2")
+}