uses ... COMOBJ, ActiveX..


function GetSignerCertificate (ThumbprintOrSerialNumber: AnsiString; var res: Olevariant): boolean;
var
  Store: Olevariant;
  Crts: OleVariant;
  count: longint;
  ii: longint;
  Crt: OleVariant;
begin
  Result := False;
  Store := COMOBJ.CreateOleObject('CAdESCOM.Store');
  Store.Open(2);
  Crts := Store.Certificates;
  count := Crts.Count;
  for ii := 1 to count do
  begin
    Crt := Crts.item[ii];
    if Crt.SerialNumber = ThumbprintOrSerialNumber then
    begin
      res := Crt;
      Result := True;
      break;
    end;
    if Crt.Thumbprint = ThumbprintOrSerialNumber then
    begin
      res := Crt;
      Result := True;
      break;
    end;
  end;
end;

procedure TForm2.Button2Click(Sender: TObject);
var
  sSerialNumber: AnsiString;
  oSigner: Olevariant;
  outCTR: Olevariant;
  oSignedData: OleVariant;
  sSignedData: OleVariant;
  Buffer: WideString;
  FileStm: TFileStream;
begin
 if OpenDialog1.Execute then
 begin
  FileStm := TFileStream.Create(OpenDialog1.FileName, fmOpenRead or fmShareDenyWrite);
  try
    Pointer(Buffer) := ActiveX.SysAllocStringByteLen(nil, FileStm.Size);
    FileStm.ReadBuffer(Pointer(Buffer)^, FileStm.Size);
  finally
    FreeAndNil(FileStm);
  end;

  sSerialNumber := inputbox('Поиск сертификата', 'Введите серийный номер или отпечаток:', '01F349E07AC40CD480E8119BF4C5BB9FE2');
  oSigner := COMOBJ.CreateOleObject('CAdESCOM.CPSigner');    {}
  if GetSignerCertificate(sSerialNumber, outCTR) then         {если нашли указанный сертификат}
  begin
    oSigner.Certificate := outCTR;                           {}
    oSignedData := COMOBJ.CreateOleObject('CAdESCOM.CadesSignedData'); {}
    oSignedData.ContentEncoding := 0; //  или  1;                                  {}
    oSignedData.Content := Buffer; // или при ContentEncoding  кодировать => 'U29tZSBEYXRhLg==';                         {}
    sSignedData := oSignedData.SignCades(oSigner, {CADES_BES}1, True, {CAPICOM_ENCODE_BASE64}0);   {получаем подписанные данные}
    Logs.Text := sSignedData;
    Logs.Lines.SaveToFile(OpenDialog1.FileName+'.p7s');
    Application.ProcessMessages;
    try
      oSignedData.VerifyCades(sSignedData, {CADES_BES}1, True);  {проверяем подписанные данные}
      ShowMessage('Подпись верна')
    except
      on E: Exception do
        ShowMessage('Подпись не верна: ' + E.Message)
    end;
  end;
 end;
end;