Реализация алгоритмов шифрования на Delphi / Gronsfeld / Unit1

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
Button1: TButton;
Label1: TLabel;
Edit1: TEdit;
Label2: TLabel;
Edit2: TEdit;
Label3: TLabel;
Edit3: TEdit;
Label4: TLabel;
Button2: TButton;
Edit4: TEdit;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Edit3KeyPress(Sender: TObject; var Key: Char);
procedure Edit2KeyPress(Sender: TObject; var Key: Char);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;
keystr,keys,msg,emsg,demsg:string;
implementation
{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var i,cod:integer;
sym:integer;
begin
cod:=1;
emsg:='';
keystr:='';
keys:=Edit2.Text;
msg:=Edit1.Text;
for i:=1 to length(msg) do
begin
keystr:=keystr+keys[cod];
inc(Cod);
if cod>length(keys) then cod:=1;
end;
for i:=1 to length(msg) do
begin
sym:=ord(msg[i])+StrToInt(keystr[i]);
if sym>255 then emsg:=emsg+char(sym-255+223)
else emsg:=emsg+char(sym);
end;
Edit3.Text:=emsg;
end;

procedure TForm1.Button2Click(Sender: TObject);
var i,cod:integer;
sym:integer;
begin
cod:=1;
demsg:='';
keystr:='';
emsg:=Edit3.Text;
keys:=Edit2.Text;
for i:=1 to length(emsg) do
begin
keystr:=keystr+keys[cod];
inc(Cod);
if cod>length(keys) then cod:=1;
end;
for i:=1 to length(emsg) do
begin
sym:=ord(emsg[i])-StrToInt(keystr[i]);
if sym<224 then demsg:=demsg+char(sym+255-223)
else demsg:=demsg+char(sym);
end;
Edit4.Text:=demsg;
end;

procedure TForm1.Edit3KeyPress(Sender: TObject; var Key: Char);
begin
if not (key in ['а'..'я', #8]) then key:=#0;
end;

procedure TForm1.Edit2KeyPress(Sender: TObject; var Key: Char);
begin
if not (key in ['0'..'9', #8]) then key:=#0;
end;

end.