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The face up and face down cards would really be numbers, and the “machine” means applying some algorithm to the numbers to combine and then check them. Bob coul

The face up and face down cards would really be numbers, and the “machine” means applying some algorithm to the numbers to combine and then check them. Bob could do that by himself. The key idea is that these numbers somehow don’t reveal which digit goes where.

fiatjaf 5y ago
Why can't Bob just look at all cards as he pleases?
- chaboud 5y ago
  Typically the “mixing of the cards” is done via a one-way function (e.g., modular arithmetic), making it impractical to fake and impractical to reverse.