Dave
re BOB: “Because disclosing personal information to relying-party customers like the wine seller would be giving away its only asset for free, it strongly resists disclosing personal information to its relying-party customers.”

I believe Bob’s logic is flawed in this assumption because :
A. The oracle is not giving the info away for free. He has already stated that they charge money for this (limited) info. (BTW is there a way of giving something away that is not ‘for free’?)
B. Given that this is the business model, the oracle would clearly be tempted or encouraged to charge more money for more info.
C. Any entity would be tempted to sell all of its info for the right price. This is the model of most credit agencies, and if/when faced with possible bankruptcy . . .
D. The info has a time value and is worth less tomorrow than it is today (unless it is maintained by the source [Bob] for zero cost).
E. Fraud, by employees etc . . .
F. In today’s world this oracle already exists, as a bank or credit-card provider (or eBay/PayPal).

Allan Milgate

PS Dave is your point 5) correct ? “The oracle tells Bob’s bank to debit that amount” twice! . . .see your point 2)”