In the context of PCI DSS, hashing must be applied to which data to render unreadable?

In the context of PCI DSS, hashing must be applied to which data to render unreadable?

• A. The entire PAN
• B. Only the last four digits of the PAN
• C. The hash code can be used without the PAN
• D. The cardholder name and PAN together

Answer: (A)

Rendering unreadable means protecting the card number (PAN) so that even if data is accessed, the number cannot be read. PCI DSS allows several methods to do this, including one-way hashes. The idea is to apply the protection to the full PAN, not just a part of it, because leaving parts of the PAN visible keeps the data traceable and usable. Hashing the entire PAN creates an irreversible representation, so the original number can’t be reconstructed from the stored value. Hashing only the last four digits leaves most of the PAN exposed and does not satisfy the requirement to render the entire PAN unreadable. Using a hash without the PAN doesn’t protect the PAN itself, and hashing the cardholder name together with the PAN doesn’t address rendering the PAN unreadable on its own. So the best approach is to apply a one-way hash to the entire PAN to render it unreadable.

Rendering unreadable means protecting the card number (PAN) so that even if data is accessed, the number cannot be read. PCI DSS allows several methods to do this, including one-way hashes. The idea is to apply the protection to the full PAN, not just a part of it, because leaving parts of the PAN visible keeps the data traceable and usable. Hashing the entire PAN creates an irreversible representation, so the original number can’t be reconstructed from the stored value. Hashing only the last four digits leaves most of the PAN exposed and does not satisfy the requirement to render the entire PAN unreadable. Using a hash without the PAN doesn’t protect the PAN itself, and hashing the cardholder name together with the PAN doesn’t address rendering the PAN unreadable on its own. So the best approach is to apply a one-way hash to the entire PAN to render it unreadable.