Data Masking

Data masking hides or substitutes selected values in a representation. A screen might show only the final digits of a phone number. A test dataset might replace names with invented values. The protection depends on what was changed and which originals remain accessible.

A hidden field may still be delivered

If an API sends a full address and the browser merely hides it, the address already reached the client. An export or another endpoint may expose it too. Enforce field restrictions before data crosses the relevant access boundary.

Substitution does not establish anonymity

A masked name does not remove identifying information from a message, rare purchase, or precise location. Consistent replacements can also preserve links between records. Evaluate the resulting dataset and the recipient's other information.

For testing, check that substitutions retain the relationships needed by the test without preserving unnecessary personal detail. Keep the original and any lookup mapping under their own access and retention rules.

Reference: NIST SP 800-188.