Which of the following methods is NOT used to make cardholder data unreadable?

The method identified as NOT used to make cardholder data unreadable is storage. In the context of PCI DSS, making cardholder data unreadable is a key security requirement aimed at protecting sensitive information from unauthorized access.

Truncation, encryption, and masking are all techniques specifically designed to obscure cardholder data:

• Truncation involves reducing the length of the cardholder data to prevent the full number from being displayed. For instance, showing only the last four digits of a credit card number allows transactions to be verified without exposing the full number.

• Encryption transforms cardholder data into a format that cannot be interpreted without a decryption key. This means that, even if data is intercepted or accessed without authorization, it remains secure and unreadable.

• Masking, on the other hand, is a method that displays only portions of the cardholder data while concealing the rest. For example, in online transactions, only the last few digits of the credit card number may be displayed, keeping the sensitive information hidden.

In contrast, storage is simply the act of keeping data in a database or file system; it does not incorporate any specific methods for rendering the data unreadable. Therefore, while data may be stored securely, just storing cardholder data