Data commit

Task/Chaocipher/Visual-Basic-.NET/chaocipher.vb

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+Module Module1
+
+    ReadOnly L_ALPHABET As String = "HXUCZVAMDSLKPEFJRIGTWOBNYQ"
+    ReadOnly R_ALPHABET As String = "PTLNBQDEOYSFAVZKGJRIHWXUMC"
+
+    Enum Mode
+        ENCRYPT
+        DECRYPT
+    End Enum
+
+    Function Exec(text As String, mode As Mode, Optional showSteps As Boolean = False) As String
+        Dim left = L_ALPHABET.ToCharArray()
+        Dim right = R_ALPHABET.ToCharArray()
+        Dim eText(text.Length - 1) As Char
+        Dim temp(25) As Char
+
+        For i = 0 To text.Length - 1
+            If showSteps Then Console.WriteLine("{0} {1}", String.Join("", left), String.Join("", right))
+            Dim index As Integer
+            If mode = Mode.ENCRYPT Then
+                index = Array.IndexOf(right, text(i))
+                eText(i) = left(index)
+            Else
+                index = Array.IndexOf(left, text(i))
+                eText(i) = right(index)
+            End If
+            If i = text.Length - 1 Then Exit For
+
+            'permute left
+
+            For j = index To 25
+                temp(j - index) = left(j)
+            Next
+            For j = 0 To index - 1
+                temp(26 - index + j) = left(j)
+            Next
+            Dim store = temp(1)
+            For j = 2 To 13
+                temp(j - 1) = temp(j)
+            Next
+            temp(13) = store
+            temp.CopyTo(left, 0)
+
+            'permute right
+
+            For j = index To 25
+                temp(j - index) = right(j)
+            Next
+            For j = 0 To index - 1
+                temp(26 - index + j) = right(j)
+            Next
+            store = temp(0)
+            For j = 1 To 25
+                temp(j - 1) = temp(j)
+            Next
+            temp(25) = store
+            store = temp(2)
+            For j = 3 To 13
+                temp(j - 1) = temp(j)
+            Next
+            temp(13) = store
+            temp.CopyTo(right, 0)
+        Next
+
+        Return eText
+    End Function
+
+    Sub Main()
+        Dim plainText = "WELLDONEISBETTERTHANWELLSAID"
+        Console.WriteLine("The original plaintext is : {0}", plainText)
+        Console.WriteLine(vbNewLine + "The left and right alphabets after each permutation during encryption are :" + vbNewLine)
+        Dim cipherText = Exec(plainText, Mode.ENCRYPT, True)
+        Console.WriteLine(vbNewLine + "The ciphertext is : {0}", cipherText)
+        Dim plainText2 = Exec(cipherText, Mode.DECRYPT)
+        Console.WriteLine(vbNewLine + "The recovered plaintext is : {0}", plainText2)
+    End Sub
+
+End Module