Santa must have a way to hash humans. There's no way he's using names. There'd be too many collisions on the Naughty list.—
InfoSec Taylor Swift (@SwiftOnSecurity) December 25, 2014
While there are alternative explanations for how the naughty/nice list is generated, hashing is important: Santa could be using a Bloom filter, in which false positive matches are possible, but false negatives are not (i.e. a query returns either “possibly in set” or “definitely not in set”, thus it has a 100% recall rate).
(Merry Christmas…and watch out!)