Hashing

Hashing is scrambling an email or phone number into a fixed string of characters before you share it, so the raw detail never leaves your hands.

Before your customer list goes to a platform, each email gets run through a one-way math process, usually one called SHA-256. The address turns into a long jumble of letters and numbers that cannot be reversed back into the original. The platform hashes its own users the same way and compares the jumbles. Matching strings mean the same person, without either side reading the actual email.

Take one address, run it through a SHA-256 tool, and the same input always produces the exact same scrambled output. That is the whole trick. The platform never sees the address you started with, only the scramble, and it can still tell two identical addresses apart from two different ones.

Hashing protects the data, but only if you prepare it right first. A stray capital letter or an extra space changes the output completely, so lists have to be trimmed and lowercased before hashing or perfectly good customers will silently fail to match.

Same person in, same scramble out. That is how they match you without seeing you.