Quiz Entry - updated: 2026.07.14
What are the three methods for generating pseudonyms?
Pseudonyms can be generated deterministically (using hash functions), arbitrarily (using user-chosen secrets), or randomly (using random procedures).
The three generation methods:
| Method | How it works | Example |
|---|---|---|
| Deterministic | Key-dependent one-way or hash function applied to identity data | Hashing an email address — same input always produces the same hash |
| Arbitrary | User chooses a secret that generates the pseudonym via a fixed algorithm | Passphrase "Sunshine123" consistently generates the same pseudonym |
| Random | Freely chosen or generated via a random process | Combining random words (e.g., "BlueTiger42") or using UUID generators |
Key properties:
- Deterministic pseudonyms are consistent — the same input always yields the same output, which is useful for linking records across datasets without revealing identity
- Arbitrary pseudonyms give users control but depend on secrecy of the passphrase
- Random pseudonyms offer the strongest unlinkability since there's no pattern to exploit
Tip: Deterministic pseudonymization (hashing) has a weakness — if the input space is small (e.g., email addresses of a company's 500 employees), an attacker can hash all possible inputs and match them. This is why salted hashing or keyed HMAC is preferred.