Re: Blockchain ?
Worth noting that once data is in a blockchain, it's there forever, unless the blockchain was designed to remove data before creation.
Yes, all the banks and other people getting excited by blockchains recently mostly haven't considered this at all. Other than suggesting that blockchains should be exempt from GDPR!
https://www.theverge.com/2018/4/5/17199210/blockchain-coin-center-gdpr-europe-bitcoin-data-privacy