pseudonimisega

Pseudonimisega refers to the data processing technique of pseudonymisation, where identifying fields within a dataset are replaced by artificial identifiers, or pseudonyms. The mapping between pseudonyms and real identifiers is stored separately and protected by strict access controls. Pseudonymised data can still be linked to a specific person if the additional information (the key or linkage file) is available, so it is considered personal data under many privacy frameworks, including GDPR; as such, processing is subject to data protection rules, though the data bear lower privacy risk and may be used for analytics and research under appropriate safeguards.

Common methods include tokenization (replacing sensitive values with tokens stored in a secure vault), encryption (reversible protection with a separate key), and data masking or hashing with a salt. The choice depends on whether re-identification is intended or needs to be prevented entirely; truly irreversible anonymisation requires different techniques.

Pseudonymisation supports privacy-by-design and can facilitate data sharing, processing for research, quality control, and cross-border analytics while reducing exposure. However, it does not eliminate risk: attackers with external data, poor key management, or insufficient separation between the pseudonym map and the dataset can re-identify individuals. Therefore, pseudonymisation should be accompanied by strong governance, including encryption and key management, access controls, DPIAs, data minimisation, and audit trails.

See also: anonymisation, de-identification, privacy-enhancing technologies.