Which THREE techniques are commonly used to achieve 'Pseudonymization' for PII in data sets?
Partial masking conceals portions of an identifier, such as the last digits of a phone number, so the record cannot directly identify an individual while retaining some utility. This satisfies pseudonymisation by weakening identifiability without full erasure.
Why this answer
Partial masking (A) is correct because it replaces part of a PII value with a placeholder (e.g., showing only the last four digits of an account number), which preserves some utility while preventing direct identification and can be reversed only with additional reference data, fitting the pseudonymization goal of replacing direct identifiers with artificial ones. Hashing with a secure salt (C) is correct because a salted cryptographic hash maps an identifier to a consistent pseudonym that supports matching or joins without revealing the original value, and the salt defends against rainbow-table and precomputation attacks. Tokenization (D) is correct because it substitutes a sensitive value with a non-sensitive surrogate token whose mapping to the original data is held in a separate, protected token vault, which is a canonical pseudonymization technique.
Data deletion (B) is not pseudonymization because it irreversibly removes the data rather than replacing identifiers, and encryption without key management (E) is not a valid pseudonymization technique since pseudonymization requires controlled re-identification via separately kept keying material, which is absent here.
Exam trap
CDPSE often tests the boundary between pseudonymization and anonymization — candidates select deletion or unmanaged encryption, missing that pseudonymization requires reversible-but-separated substitution techniques like masking, salted hashing, and tokenization.