String Crypter

program Window;

uses Windows, Messages;

{$R *.RES}

var
wClass:   TWndClass;  // class struct for main window
hFont,                // handle of font
hInst,                // handle of program (hinstance)
Handle,               // handle of main window
hEncrypt,             // handle of encrypt button
hDecrypt,             // handle of decrypt button
hEdit,                // handle of main edit
hLabel,               // handle of password label
hPW:      HWND;       // handle of password edit
Msg:      TMSG;       // message struct
dEncrypt,
dDecrypt: Pointer;    // default button procedures


// This lines everything up
procedure Resize;
var
RCT:TRect;
begin
  GetWindowRect(Handle,RCT);
  MoveWindow(hPW,230,5,RCT.Right-RCT.Left-245,24,True);
  MoveWindow(hEdit,5,34,RCT.Right-RCT.Left-20,RCT.Bottom-RCT.Top-66,True);
end;

// This is to cleanup and stop the program
procedure ShutDown;
begin
  DeleteObject(hFont);
  UnRegisterClass('Sample Class',hInst);
  ExitProcess(hInst); //end program
end;

// Decrypts the text in hEdit with the text in hPW
procedure Decrypt;
var
x,i,                // count variables
sText,sPW: Integer; // size of Text, PW
Text,PW:   PChar;   // buffer for Text, PW
begin
  sText:=GetWindowTextLength(hEdit)+1;
  sPW:=GetWindowTextLength(hPW)+1;
  GetMem(Text,sText);
  GetMem(PW,sPW);
  GetWindowText(hEdit,Text,sText);
  GetWindowText(hPW,PW,sPW);
  x:=0; // initialize count
  for i:=0 to sText-2 do
  begin
    Text[i]:=Chr(Ord(Text[i])-Ord(PW[x]));
    Inc(x);
    if x=(sPW-1)then x:=0;
  end;
  SetWindowText(hEdit,Text);
  FreeMem(Text);
  FreeMem(PW);
end;

// Encrypts the text in hEdit with the text in hPW
procedure Encrypt;
var
x,i,                // count variables
sText,sPW: Integer; // size of Text, PW
Text,PW:   PChar;   // buffer for Text, PW
begin
  sText:=GetWindowTextLength(hEdit)+1;
  sPW:=GetWindowTextLength(hPW)+1;
  GetMem(Text,sText);
  GetMem(PW,sPW);
  GetWindowText(hEdit,Text,sText);
  GetWindowText(hPW,PW,sPW);
  x:=0; // initialize count
  for i:=0 to sText-2 do
  begin
    Text[i]:=Chr(Ord(Text[i])+Ord(PW[x]));
    Inc(x);
    if x=(sPW-1)then x:=0;
  end;
  SetWindowText(hEdit,Text);
  FreeMem(Text);
  FreeMem(PW);
end;

// This function processes every message sent to the Encrypt Button
function EncryptProc(hWnd,Msg,wParam,lParam:Longint):Longint; stdcall;
var
i: Integer;
begin
  // Always pass the message to the Default procedure
  Result:=CallWindowProc(dEncrypt,hWnd,Msg,wParam,lParam);

  case Msg of
  // If the user presses TAB we're gunna switch the
  // focus over to the Decrypt button.
  WM_KEYDOWN: if wParam=9 then SetFocus(hDecrypt);
  end;

end;

// This function processes every message sent to the Decrypt Button
function DecryptProc(hWnd,Msg,wParam,lParam:Longint):Longint; stdcall;
begin
  // Always pass the message to the Default procedure
  Result:=CallWindowProc(dEncrypt,hWnd,Msg,wParam,lParam);

  case Msg of
  // if the user presses TAB we're gunna switch
  // the focus back to the Encrypt button.
  WM_KEYDOWN: if wParam=9 then SetFocus(hEncrypt);
  end;

end;

// This function processes every message sent to our Main window
function WindowProc(hWnd,Msg,wParam,lParam:Longint):Longint; stdcall;
begin
  // Always pass the message to the Default procedure
  Result:=DefWindowProc(hWnd,Msg,wParam,lParam);

  case Msg of
  WM_SIZE:    Resize;
  // When buttons are clicked the message is passed to
  // the parent window, so we handle it here.
  WM_COMMAND: if      lParam=hEncrypt then Encrypt
              else if lParam=hDecrypt then Decrypt;
  WM_DESTROY: ShutDown;
  end;

end;

// This is the main program function (WinMain)
begin

  hInst:=GetModuleHandle(nil); // get the application instance
                               // hInstance returns zilch

  with wClass do
  begin
    Style:=         CS_PARENTDC;
    hIcon:=         LoadIcon(hInst,'MAINICON');
    lpfnWndProc:=   @WindowProc;
    hInstance:=     hInst;
    hbrBackground:= COLOR_BTNFACE+1;
    lpszClassName:= 'Sample Class';
    hCursor:=       LoadCursor(0,IDC_ARROW);
  end;

  // Once our class is registered we
  // can start making windows with it
  RegisterClass(wClass);

  // Create our main window
  Handle:=CreateWindow(
    'Sample Class',          // Registered Class Name
    'Encrypter',             // Title of Window
    WS_OVERLAPPEDWINDOW or   // Basic Window Style
    WS_VISIBLE,              // Make it Visible
    10,                      // Left
    10,                      // Top
    400,                     // Width
    300,                     // Height
    0,                       // Parent Window Handle
    0,                       // Handle of Menu
    hInst,                   // Application Instance
    nil);                    // Structure for Creation Data

  // Create the Encrypt button
  hEncrypt:=CreateWindow(
    'Button',
    'Encrypt',
    WS_VISIBLE or WS_CHILD or BS_PUSHLIKE or BS_TEXT,
    5,5,65,24,Handle,0,hInst,nil);

  // Create the Decrypt button
  hDecrypt:=CreateWindow(
    'Button',
    'Decrypt',
    WS_VISIBLE or WS_CHILD or BS_PUSHLIKE or BS_TEXT,
    75,5,65,24,Handle,0,hInst,nil);

  // Create the main Edit
  hEdit:=CreateWindowEx(
    WS_EX_CLIENTEDGE, // this EX style is for the beveled edge
    'Edit',
    '',
    WS_VISIBLE or WS_CHILD or ES_LEFT or ES_MULTILINE or ES_WANTRETURN or ES_AUTOVSCROLL or WS_VSCROLL,
    5,34,380,234,Handle,0,hInst,nil);

  // Create the password Edit
  hPW:=CreateWindowEx(
    WS_EX_CLIENTEDGE,
    'Edit',
    '',
    WS_VISIBLE or WS_CHILD or ES_LEFT or ES_AUTOHSCROLL or ES_PASSWORD,
    230,5,155,24,Handle,0,hInst,nil);

  hLabel:=CreateWindow(
    'Static',
    'Password:',
    WS_VISIBLE or WS_CHILD or SS_LEFT,
    160,10,70,20,Handle,0,hInst,nil);

  // Create a custom font for our window otherwise
  // everything would use the system font (blech!)
  hFont:=CreateFont(
    -12,                           // Height
    0,                             // Width
    0,                             // Angle of Rotation
    0,                             // Orientation
    0,                             // Weight
    0,                             // Italic
    0,                             // Underline
    0,                             // Strike Out
    DEFAULT_CHARSET,               // Char Set
    OUT_DEFAULT_PRECIS,            // Precision
    CLIP_DEFAULT_PRECIS,           // Clipping
    DEFAULT_QUALITY,               // Render Quality
    DEFAULT_PITCH or FF_DONTCARE,  // Pitch & Family
    'MS Sans Serif');              // Font Name

  // Set the fonts for all our controls
  SendMessage(hEncrypt,WM_SETFONT,hFont,0);
  SendMessage(hDecrypt,WM_SETFONT,hFont,0);
  SendMessage(hEdit,WM_SETFONT,hFont,0);
  SendMessage(hPW,WM_SETFONT,hFont,0);
  SendMessage(hLabel,WM_SETFONT,hFont,0);

  // Subclass Encrypt Button (assign it a custom WindowProc)
  dEncrypt:=Pointer(GetWindowLong(hEncrypt,GWL_WNDPROC));
  SetWindowLong(hEncrypt,GWL_WNDPROC,Longint(@EncryptProc));

  // Subclass Decrypt Button
  dDecrypt:=Pointer(GetWindowLong(hDecrypt,GWL_WNDPROC));
  SetWindowLong(hDecrypt,GWL_WNDPROC,Longint(@DecryptProc));

  // The reason I don't subclass the Edit controls here
  // is because they don't do anything custom. If I wanted
  // them to Beep or something whenever you typed a "G" then
  // I would subclass them.

  // Focus on first control (otherwise people with no mouse are screwed)
  SetFocus(hEncrypt);

  // Now we loop GetMessage to process each Message in
  // our main window's message list. Every time the main
  // window recieves a message its added to the list, so
  // this loop here will eventually process it.

  while(GetMessage(Msg,Handle,0,0))do
  begin
    TranslateMessage(Msg);             // Translate any keyboard Msg's
    DispatchMessage(Msg);              // Send it to our WindowProc
  end;                                 // for processing.

end.