Just use Chinese. Your signature is a symbol of your personal identity. The whole world can sign in Chinese, as long as it is guaranteed that it is not easy to be counterfeited, and all signatures are unified, and English is not needed, let alone Persian. Don't write too neatly, you can scribble a little, so it's less easy to be copied. I have met some foreigners who don't even have their own names. They just seem to have drawn a circle casually, but that circle is his handwriting, and the others are not easy to copy.