In Part 1 you built a map: every column that holds PII, tagged with a tier. Feels like the hard part is over. Then someone in #data-platform asks the reasonable question:
"OK so... do we hash the emails? Or mask them? I feel like hashing. Let's hash them."
"Hash it" is the two-word answer that's almost always wrong in an interesting way. Not because hashing is bad — because the question wasn't "which algorithm," it was "what do we still need this data to do?" This article is about answering that question deliberately. All code is in the companion repo — every claim below has a runnable file behind it.
One map before the weapons
Every technique fits somewhere on one axis that matters more than people admit: can the original value be recovered?
