With many of us spending our time online, we tend to be laser-focused on preventing our personal information from falling into the hands of nefarious hackers. But let’s not forget about the security of print-based communications.
Remember how the ink appears and disappears on the Marauder’s Map that appears in Harry Potter and the Prisoner of Azkaban? Basically, scientists are trying to recreate this bit of magic to protect information. But instead of using a password to make the invisibl