Question

A retail company must stop storing raw primary account numbers (PANs) in its order management, analytics, and loyalty systems, but downstream reports still need to correlate repeat purchases by the same card across all three systems. The privacy engineer is designing a technical control. Which approach best meets the privacy objective while preserving cross-system correlation?

Accepted Answer

Apply deterministic (vault-based) tokenization so the same PAN always maps to the same token, and restrict token-to-PAN reversal to an isolated token vault with strict access controls

Answer

Encrypt the PAN with a random initialization vector in each system so ciphertext differs everywhere, distributing the decryption key to each application

Answer

Hash the PAN with an unsalted SHA-256 digest in each system and store the digest instead of the PAN

Answer

Truncate the PAN to the last four digits in every system and discard the remaining digits