Шифр Виженера

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
 
type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Memo1: TMemo;
    Memo2: TMemo;
    SaveDialog1: TSaveDialog;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
function Viz_Crypt(s,key:string):string;
const
SizeA = 33; //Ðàçìåð àëôàâèòà
RusA = 'àáâãäå¸æçèéêëìíîïðñòóôõö÷øùúûüýþÿ'; 
var i, P, t :integer;
temp:string;
begin
s:=AnsiLowerCase(s);
key:=AnsiLowerCase(key);
t:=0;
for i:=1 to length(s) do
begin
inc(t);
if t>length(key) then t:=1;
P:=pos(s[i],RusA)+pos(key[t],RusA);
if P>SizeA then P:=P-SizeA;
Result:=Result+RusA[P];
end;
end;
 
 
function Viz_DeCrypt(s,key:string):string;
const
SizeA = 33; 
RusA = 'àáâãäå¸æçèéêëìíîïðñòóôõö÷øùúûüýþÿ'; 
var i, P, t :integer;
temp:string;
begin
s:=AnsiLowerCase(s);
key:=AnsiLowerCase(key);
t:=0;
for i:=1 to length(s) do
begin
inc(t);
if t>length(key) then t:=1;
P:=pos(s[i],RusA)-pos(key[t],RusA);  
if P<=0 then P:=P+SizeA;
Result:=Result+RusA[P];
end;
end;
 
{$R *.dfm}
 
procedure TForm1.Button1Click(Sender: TObject);
begin
memo2.Text:=Viz_Crypt(memo1.Text,edit1.Text);
end;
 
procedure TForm1.Button2Click(Sender: TObject);
begin
memo2.Text:=Viz_DeCrypt(memo1.Text,edit1.Text);
end;
 
procedure TForm1.Button3Click(Sender: TObject);
begin
memo1.Lines.Clear;
memo2.Lines.Clear;
edit1.Text:='';
end;
 
procedure TForm1.Button4Click(Sender: TObject);
begin
if(SaveDialog1.Execute=true) then
memo2.Lines.SaveToFile(SaveDialog1.FileName+'.txt');
end;
 
end.