[giantrobot]

You're just describing signing tokens which has been around for decades with smart cards. There's no need for a blockchain to be involved in that process. It just makes it slower, expensive, and public.

If you want some personal data to show up somewhere be it a name or avatar it has to leave your device. At that point someone can and will copy that data. If there's value with associating that data with your activity someone will do it.