A permissionless blockchain and where to store personal data under GDPR?
A hash is stored 1-to-1 to a Public Key. This Public Key can then be used to find the balance of the value kept in the blockchain (e.g. Bitcoin). Also a public key from the blockchain is traceable to a Hash but cannot be traced back to any id (given the one-way property of a cryptographic Hash) and not even, because of using a salt, by using a dictionary or a rainbow-table attack, thus leading to anonymity in the consortium's database. The introduction of a timestamp in the Hash function even strengthens anonymity by enabling the reuse of public keys.
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