id: "SI-19(04)" title: "Removal, Masking, Encryption, Hashing, or Replacement of Direct Identifiers" family: "SI" family_name: "System and Information Integrity" sort_id: "si-19.04" priority: "P1" implementation_level: "system" parent: "SI-19" enhancement: True
Statement
Remove, mask, encrypt, hash, or replace direct identifiers in a dataset.
Guidance
There are many possible processes for removing direct identifiers from a dataset. Columns in a dataset that contain a direct identifier can be removed. In masking, the direct identifier is transformed into a repeating character, such as XXXXXX or 999999. Identifiers can be encrypted or hashed so that the linked records remain linked. In the case of encryption or hashing, algorithms are employed that require the use of a key, including the Advanced Encryption Standard or a Hash-based Message Authentication Code. Implementations may use the same key for all identifiers or use a different key for each identifier. Using a different key for each identifier provides a higher degree of security and privacy. Identifiers can alternatively be replaced with a keyword, including transforming "George Washington" to "PATIENT" or replacing it with a surrogate value, such as transforming "George Washington" to "Abraham Polk."
Assessment Objective
direct identifiers in a dataset are removed, masked, encrypted, hashed, or replaced.
System and information integrity policy
system and information integrity procedures
personally identifiable information processing policy
de-identification procedures
system configuration
documentation of de-identified datasets
tools for the removal, masking, encryption, hashing or replacement of direct identifiers
system security plan
privacy plan
privacy impact assessment
privacy risk assessment documentation
other relevant documents or records
Organizational personnel responsible for de-identifying the dataset
organizational personnel with information security and privacy responsibilities
Automated mechanisms supporting and/or implementing the removal, masking, encryption, hashing or replacement of direct identifiers