PCI DSS Requirement 3.4 states that PAN must be rendered unreadable when stored. Which of the following may be used to meet this requirement?

The requirement that Primary Account Number (PAN) must be rendered unreadable when stored is critical for protecting sensitive payment card data. Using strong cryptography to hash the entire PAN is a compliant method for meeting this requirement.

When a PAN is hashed with a secure algorithm, the original data is transformed into a unique string that is irreversible. This means that even if the hashed data is exposed, it cannot be easily converted back to the original PAN, thus effectively protecting the sensitive information. Strong cryptographic methods ensure that the hash cannot be easily broken, maintaining the confidentiality and integrity of the stored data.

In contrast, storing the PAN in plain text poses significant risks, as anyone with access to the storage can view the sensitive information directly. Similarly, encrypting the PAN using a weak cipher would not provide adequate security; weak encryption can often be cracked, compromising the sensitive data. Lastly, while storing only the last four digits of the PAN does limit the exposure of the complete account number, it does not fulfill the requirement to render the entire PAN unreadable. Therefore, using strong cryptography to hash the entire PAN is the correct and compliant solution to ensure the protection of cardholder data.