Шифрование методом Вижинера

Пример
example
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СССССССССССССССССС

const TViginer: string = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
 
function ViginerEncipher(toCode, K: string): string;
var
  i: integer;
  currK: byte;
  s: string;
begin
  s := '';
  for i := 1 to length(toCode) do begin
  currK := pred(pos(K[ (pred(i) mod length(K)) + 1 ], TViginer));
  s := s +
  TViginer[ ((pred(pos(toCode[ i ], TViginer)) + currK) mod length(TViginer)) + 1 ];
  end;
  ViginerEncipher := s;
end;
 
  function ViginerDecipher(toDecode, K: string): string;
  var
  i, T: integer;
  currK: byte;
  s: string;
begin
  s := '';
  for i := 1 to length(toDecode) do begin
  currK := pred(pos(K[ (pred(i) mod length(K)) + 1 ], TViginer));
  T := pred(pos(toDecode[ i ], TViginer)) - currK;
  if T < 0 then inc(T, length(TViginer));
  s := s + TViginer[T + 1];
  end;
  ViginerDecipher := s;
end;
 
  procedure DecryptViger(NameInput, NameOutput: string; pass: string);
  var f_in,f_out:TextFile;
   s:string;
begin
   AssignFile(f_in,NameInput);
   AssignFile(f_out,NameOutput);
   ReSet(f_in);
   ReWrite(f_out);
   while not eof(f_in) do
   begin
     readln(f_in,s);
     s:= ViginerDecipher(s, pass) ;
     write(f_out,s);
   end;
   CloseFile(f_in);
   CloseFile(f_out);
 
 
end;
 
 
procedure cryptFileViginer(NameInput,NameOutput:string; pass:string);
 var f_in,f_out:TextFile;
   s:string;
begin
   AssignFile(f_in,NameInput);
   AssignFile(f_out,NameOutput);
   ReSet(f_in);
   ReWrite(f_out);
   while not eof(f_in) do
   begin
     readln(f_in,s);
     s:= ViginerEncipher(s, pass) ;
     write(f_out,s);
   end;
   CloseFile(f_in);
   CloseFile(f_out);
 
 
end;

inputName:=UTF8ToSys(leInput.Text);
  outputName:=UTF8ToSys(leOutput.Text);

currK := pred(pos(K[ (pred(i) mod length(K)) + 1 ], TViginer));