4 ms·

Anonymization is supposed to be irreversible. This scheme is reversible by whoever has the key. I don't really get the point of it.

• true_religion 1y ago
  Any stable hash can't truly anonymize IP addresses because there is a finite amount of outputs easily computable via ordinary machines.
  • atoav 1y ago
    Which is why we pepper and salt our hashes. If you store the blood type of a patient hashed, the problem is that there are only so many blood types. So the same blood type will have the same hash value and attackers could (1) just infer statistically which are which, (2) crack one and get the rest and (3) group users even without cracking the hash. That means we need to ensure the input values are getting more complex by prefixing them with secrets from elsewhere. If you have one secret (e.g. stored in an environment variable) that would be the pepper. Adding pepper just makes cracking harder, but since it is the same for each value, it is not enough. But since it is not stored next to the input value it makes attacks harder. A salt would be a per value secret that is stored for each blood type and prepended on hash. The two in combination make it much harder to get from the hashed value to the input value without having both salt and pepper.
    • 47282847 1y ago
      That’s encryption at rest, but not anonymization, unless you throw away the salt and pepper, at which point the record becomes meaningless since it cannot serve for future comparisons.