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Pseudonymization vs anonymization

Checked against the providers’ export features in October 2026.

Before sharing an AI conversation with a colleague, a client or another AI, you may want to hide personal data. Two words get mixed up here, and the difference matters.

The difference

Pseudonymization replaces identifiers with other values — for example “Lucía Martín” becomes [PERSON_001] — while someone with the additional information (the key) could reverse it. Under the GDPR (Article 4(5)), pseudonymized data is still personal data.

Anonymization means a person can no longer be identified by any means reasonably likely to be used (GDPR Recital 26). Anonymous information is outside the GDPR — but true anonymization is hard, and no automatic tool can guarantee it.

Why aliases are not enough on their own

  • Context identifies people: “my landlady in the building next to the bakery” needs no name.
  • Rare details (job titles, places, dates, amounts) can be combined to single someone out.
  • Detectors miss things: unusual formats, nicknames, addresses and names without a cue.
  • The key reverses everything: whoever has the alias key can restore the original values.

How AI Vault helps

  • Consistent aliases: the same person or e-mail gets the same alias across the whole package, so the text still makes sense; different values get different aliases.
  • Irreversible removal for what should never be shared, such as API keys and passwords.
  • Exclusion of whole messages or sections you do not want to include.
  • A privacy list of names and terms (people, clients, codenames) that are always detected.
  • An exact preview you must confirm, and an alias key that is never inside the package.

Checklist before you share

  1. Share only the branch, messages and sections the recipient needs.
  2. Add the names of the people and companies involved to your privacy list.
  3. Review every finding; check low-confidence ones and false positives.
  4. Read the full preview for indirect identifiers (places, dates, unique details).
  5. Remove secrets; never share them pseudonymized.
  6. Keep the alias key private, or do not download it at all.

Not legal advice

This page explains general concepts. Whether a specific sharing is lawful depends on your situation; ask your data protection officer or a lawyer when in doubt.

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