Task: Vigenère cipher








VB: Option Explicit

Sub test()
Dim Encryp As String
   Encryp = Vigenere("Beware the Jabberwock, my son! The jaws that bite, the claws that catch!", "vigenerecipher", True)
   Debug.Print "Encrypt:= """ & Encryp & """"
   Debug.Print "Decrypt:= """ & Vigenere(Encryp, "vigenerecipher", False) & """"
End Sub

Private Function Vigenere(sWord As String, sKey As String, Enc As Boolean) As String
Dim bw() As Byte, bk() As Byte, i As Long, c As Long
Const sW As String = "ÁÂÃÄÅÇÈÉÊËÌÍÎÏÑÒÓÔÕÖÙÚÛÜÝ"
Const sWo As String = "AAAAACEEEEIIIINOOOOOUUUUY"
Const A As Long = 65
Const N As Long = 26

   c = Len(sKey)
   i = Len(sWord)
   sKey = Left(IIf(c < i, StrRept(sKey, (i / c) + 1), sKey), i)
   sKey = StrConv(sKey, vbUpperCase)         
   sWord = StrConv(sWord, vbUpperCase)
   sKey = StrReplace(sKey, sW, sWo)          
   sWord = StrReplace(sWord, sW, sWo)
   sKey = RemoveChars(sKey)                  
   sWord = RemoveChars(sWord)
   bk = CharToAscii(sKey)                     
   bw = CharToAscii(sWord)
   For i = LBound(bw) To UBound(bw)
      Vigenere = Vigenere & Chr((IIf(Enc, ((bw(i) - A) + (bk(i) - A)), ((bw(i) - A) - (bk(i) - A)) + N) Mod N) + A)
   Next i
End Function

Private Function StrRept(s As String, N As Long) As String
Dim j As Long, c As String
   For j = 1 To N
      c = c & s
   Next
   StrRept = c
End Function

Private Function StrReplace(s As String, What As String, By As String) As String
Dim t() As String, u() As String, i As Long
   t = SplitString(What)
   u = SplitString(By)
   StrReplace = s
   For i = LBound(t) To UBound(t)
      StrReplace = Replace(StrReplace, t(i), u(i))
   Next i
End Function

Private Function SplitString(s As String) As String()
   SplitString = Split(StrConv(s, vbUnicode), Chr(0))
End Function

Private Function RemoveChars(str As String) As String
Dim b() As Byte, i As Long
   b = CharToAscii(str)
   For i = LBound(b) To UBound(b)
      If b(i) >= 65 And b(i) <= 90 Then RemoveChars = RemoveChars & Chr(b(i))
   Next i
End Function

Private Function CharToAscii(s As String) As Byte()
   CharToAscii = StrConv(s, vbFromUnicode)
End Function




Ada: WITH Ada.Text_IO, Ada.Characters.Handling;
USE Ada.Text_IO, Ada.Characters.Handling;

PROCEDURE Main IS
   SUBTYPE Alpha IS Character RANGE 'A' .. 'Z';
   TYPE Ring IS MOD (Alpha'Range_length);
   TYPE Seq IS ARRAY (Integer RANGE <>) OF Ring;
   
   FUNCTION "+" (S, Key : Seq) RETURN Seq IS
      R : Seq (S'Range);
   BEGIN
      FOR I IN R'Range LOOP
         R (I) := S (I) + Key (Key'First + (I - R'First) MOD Key'Length);
      END LOOP;
      RETURN R;
   END "+";
   
   FUNCTION "-" (S : Seq) RETURN Seq IS
      R : Seq (S'Range);
   BEGIN
      FOR I IN R'Range LOOP
         R (I) := - S (I);
      END LOOP; 
      RETURN R;
   END "-";
   
   FUNCTION To_Seq (S : String) RETURN Seq IS
      R  : Seq (S'Range);
      I  : Integer := R'First;
   BEGIN
      FOR C OF To_Upper (S) LOOP
         IF C IN Alpha THEN
            R (I) := Ring'Mod (Alpha'Pos (C) - Alpha'Pos (Alpha'First));
            I := I + 1;
         END IF;
      END LOOP;
      RETURN R (R'First .. I - 1);
   END To_Seq;
   
   FUNCTION To_String (S : Seq ) RETURN String IS
      R : String (S'Range);
   BEGIN
      FOR I IN R'Range LOOP
         R (I) := Alpha'Val ( Integer (S (I)) + Alpha'Pos (Alpha'First));
      END LOOP;
      RETURN R;
   END To_String;
   
   Input : Seq := To_Seq (Get_Line);
   Key : Seq := To_Seq (Get_Line);
   Crypt : Seq := Input + Key;
BEGIN
   Put_Line ("Encrypted: " & To_String (Crypt));
   Put_Line ("Decrypted: " & To_String (Crypt + (-Key)));
END Main;