A woman strolls into a grocery store, thinking about grabbing some apples. Before she even reaches the produce aisle, a security camera has scanned her face. Whether the system is checking for shoplifters or simply logging her arrival, her face has joined a digital ledger, a trace she can't easily erase. Retailers, banks, airports, stadiums and office buildings are doing the same. But what if the woman's facial information is stolen or misused? If a cybercriminal steals her password, she can