Шифрование (шифром Полибия)

var
  Form1: TForm1;
  i,row,column,l:integer;
  f:boolean;
const
m=8;
n=m-1;
shifr:array[0..n, 0..n]of char=(
('a','b','c','d','e','f','g','h'),
('i','j','k','l','m','n','o','p'),
('q','r','s','t','u','v','w','x'),
('y','z','A','B','C','D','E','F'),
('G','H','I','J','K','L','M','N'),
('O','P','Q','R','S','T','U','V'),
('W','X','Y','Z','!','.',',',':'),
('?','-',' ','*','/','(',')',';'));
 
implementation
 
{$R *.lfm}
 
function ToEncode(const str:string):string;
begin
  l:=length(str);
  SetLength(Result,l)
  for i:=1 to length(str) do begin
    f:=true;
    for row:=0 to n do
    for column:=0 to n do
    if str[i]=shifr[row,column] then begin
    Result[i]:=shifr[(row+1)mod m,column];
    f:=false;
    end;
    if f then begin Result[i]:='^';
  end;
  end;
end;
function ToDecode(const str:string):string;
begin
  l:=length(str);
  SetLength(Result,l);
  for i:=1 to length(str) do begin
    f:=true;
    for row:=0 to n do
    for column:=0 to n do
    if str[i]=shifr[row,column] then begin
    Result[i]:=shifr[(row+m-1)mod m,column];
    f:=false;
    end;
    if f then begin Result[i]:='^';
  end;
end;
end;