Pseudonymization

The process of replacing directly identifying information with artificial identifiers (pseudonyms), while maintaining the ability to re-link data to the original identity using a separate key.

Why pseudonymization matters

Pseudonymization is a middle ground between full identification and anonymization. It lets you track user behavior patterns using pseudonyms while keeping the mapping to real identities separate and secure.

GDPR recommends pseudonymization as a data protection measure, but unlike anonymization, pseudonymized data is still considered personal data and subject to regulations.

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Common Mistakes

  • -Treating pseudonymized data as anonymous and applying fewer protections
  • -Storing the pseudonym mapping key alongside the pseudonymized data
  • -Not encrypting or properly securing the re-identification key

Pro Tips

  • +Use pseudonymization to enable analytics while limiting access to real identities to authorized personnel only
  • +Implement technical controls that prevent casual re-identification
  • +Review your pseudonymization approach with your DPO or legal team to ensure it meets regulatory expectations

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