I suggest an alternative approach that I just wrote a Whitepaper for, and gave a link to a github repo to demonstrate how you can verify a person who is making a purchase or purchasing tokens, is the person they say they are — through the use of digital signatures. We have the technology available today.

https://steemit.com/ethereum/@emmonspired/whitepaper-and-demo-ux-for-authenticated-and-verified-erc20-payments-using-metamask-and-ethsigutil