unit ExReg1;

interface

uses
  SysUtils, Classes,Controls, Forms, Dialogs, StdCtrls, ComCtrls, Buttons;

type

  { TfrmExRegCode }

  TfrmExRegCode = class(TForm)
    edDate: TEdit;
    GroupBox1: TGroupBox;
    Label1: TLabel;
    edtUserName1: TEdit;
    Label2: TLabel;
    Label3: TLabel;
    edtRegCode1: TEdit;
    GroupBox2: TGroupBox;
    edtUserName2: TEdit;
    Label4: TLabel;
    edtRegCode2: TEdit;
    Label5: TLabel;
    Label6: TLabel;
    edtStatus: TEdit;
    btnGenerate: TSpeedButton;
    btnVerify: TSpeedButton;
    procedure btnGenerateClick(Sender: TObject);
    procedure btnVerifyClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  frmExRegCode: TfrmExRegCode;

implementation

{$R *.lfm}

uses
  OnGuard, OgUtil;

const
  EncryptionKey : TKey = ($E5, $8F, $84, $D6, $92, $C9, $A4, $D8,
                          $1A, $FA, $6F, $8D, $AB, $FC, $DF, $B4);

procedure TfrmExRegCode.btnGenerateClick(Sender: TObject);
var
  Key : TKey;
  Code : TCode;
  Modifier : Longint;
  D : TDateTime;
var
  fs: TFormatSettings;
begin
  if not TryStrToDate(edDate.Text, D) then
  begin
    fs := FormatSettings;
    fs.ShortDateFormat := 'yyyy/mm/dd';
    fs.DateSeparator := '-';
    if not TryStrToDate(edDate.Text, D, fs) then
    begin
      MessageDlg('Invalid date.', mtError, [mbOK], 0);
      exit;
    end;
  end;
  Key := EncryptionKey;
  Modifier := StringHashELF(edtUserName1.Text);
  ApplyModifierToKeyPrim(Modifier, Key, SizeOf(Key));
  InitRegCode(Key, '', D, Code{%H-});
  edtRegCode1.Text := BufferToHex(Code, SizeOf(Code));
end;

procedure TfrmExRegCode.btnVerifyClick(Sender: TObject);
var
  Key : TKey;
  Code : TCode;
  Modifier : Longint;
begin
  Key := EncryptionKey;
  Modifier := StringHashELF(edtUserName2.Text);
  ApplyModifierToKeyPrim(Modifier, Key, SizeOf(Key));
  Code := Default(TCode);
  HexToBuffer(edtRegCode2.Text, Code, SizeOf(Code));
  if IsRegCodeValid(Key, Code) then begin
    if IsRegCodeExpired(Key, Code) then
      edtStatus.Text := 'Expired'
    else
      edtStatus.Text := 'Valid';
  end else
    edtStatus.Text := 'Not Valid';
end;

procedure TfrmExRegCode.FormCreate(Sender: TObject);
var
  fs: TFormatSettings;
begin
  fs := FormatSettings;
  fs.ShortDateFormat := 'yyyy/mm/dd';
  fs.DateSeparator := '-';
  edDate.Text := DateToStr(Now, fs);
end;

end.