unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs;

type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

const CKEY1 = 53761;
      CKEY2 = 32618;

function EncryptStr(const S :WideString; Key: Word): String;
var   i          :Integer;
      RStr       :RawByteString;
      RStrB      :TBytes Absolute RStr;
begin
  Result:= '';
  RStr:= UTF8Encode(S);
  for i := 0 to Length(RStr)-1 do begin
    RStrB[i] := RStrB[i] xor (Key shr 8);
    Key := (RStrB[i] + Key) * CKEY1 + CKEY2;
  end;
  for i := 0 to Length(RStr)-1 do begin
    Result:= Result + IntToHex(RStrB[i], 2);
  end;
end;

function DecryptStr(const S: String; Key: Word): String;
var   i, tmpKey  :Integer;
      RStr       :RawByteString;
      RStrB      :TBytes Absolute RStr;
      tmpStr     :string;
begin
  tmpStr:= UpperCase(S);
  SetLength(RStr, Length(tmpStr) div 2);
  i:= 1;
  try
    while (i < Length(tmpStr)) do begin
      RStrB[i div 2]:= StrToInt('$' + tmpStr[i] + tmpStr[i+1]);
      Inc(i, 2);
    end;//delphitop.com
  except
    Result:= '';
    Exit;
  end;
  for i := 0 to Length(RStr)-1 do begin
    tmpKey:= RStrB[i];
    RStrB[i] := RStrB[i] xor (Key shr 8);
    Key := (tmpKey + Key) * CKEY1 + CKEY2;
  end;
  Result:= UTF8Decode(RStr);

end;

procedure TForm1.FormCreate(Sender: TObject);
begin
caption:=DecryptStr(EncryptStr('中国',100),100);
end;

end.