Comparisons
Redaction vs pseudonymization: which should you use before AI?
Use pseudonymization when the AI's work has to come back to the client: consistent stand-ins keep the document readable and a locally kept key restores the names. Use permanent redaction when the document is going to a court, a counterparty or the public and must never be reversed. Generalization suits facts the task needs only roughly. Manual find-and-replace works for short, simple text but misses variants.
Last reviewed · 5 sources
What each method does
Permanent redaction deletes the text and usually leaves a black box. Pseudonymization swaps each identifier for a stand-in and keeps a key; the EDPB says the result is still "information on an identifiable natural person" and the ICO says "pseudonymous data is still personal data". Generalization replaces a precise value with a range: an age band, a region, a salary band. NIST SP 800-188 treats all three as de-identification techniques.
| Method | AI can follow who is who | Details can be restored | Best use |
|---|---|---|---|
| Pseudonymization with a local key | Yes | Yes, by the key holder | Drafting and analysis that returns to the client |
| Permanent redaction | No | No | Filing, publishing, disclosure to others |
| Generalization | Partly | No | Facts the task needs only roughly |
| Manual find-and-replace | Yes, if done consistently | Only by hand | Short, simple text |
Who should choose which
Choose permanent redaction for anything leaving your control for good: court filings, disclosure packages, public records. PiBye is not built for that; a redaction tool that burns the text out of a PDF is.
Choose pseudonymization for AI drafting, summarizing and analysis you will reuse for the client, where a document full of black boxes would give the AI nothing to reason about.
Combine them: pseudonymize for the AI work, then redact permanently if the final document is going to be published.
The ranking
Ranked by these criteria, in this order:
- Keeps the document useful to the AI
- Lets you restore the client's details afterwards
- Protects the key from the AI provider
- Effort per document
1. Best for AI work that comes back to the client
Pseudonymization with a local key (PiBye)
Consistent stand-ins, human review of every replacement, and restoration into the returned document on the Mac.
2. Best for facts the task needs only roughly
Generalization
Age bands and regions instead of dates and addresses; not reversible, and needs judgment per fact.
3. Best for a short, simple text
Manual find-and-replace
Free, but misses spelling variants, scans and hidden data, and restoring is manual.
4. Best for filing and publication
Permanent redaction (Acrobat Pro, PDF Expert)
Irreversible by design, which is right for disclosure and wrong for AI drafting.
Where PiBye fits
How PiBye handles this
PiBye pseudonymizes on your Mac, keeps the key there, and restores the real details into the returned document, including PDFs, Word files and scans. For documents that must be permanently redacted, use a redaction tool instead.
1.0.1 · macOS 14.8.5 or later · Apple Silicon · 1.1 GB
Frequently asked questions
Is pseudonymized data anonymous?
No. Whoever holds the key can reverse it, and European and UK regulators treat it as personal data.
Can I pseudonymize and then redact?
Yes. Use stand-ins for the AI work, and permanently redact the final document if it will be filed or published.
Sources
- Guidelines 01/2025 on Pseudonymisation (version for public consultation), European Data Protection Board, January 16, 2025. Checked 25 September 2026.
- How do we ensure anonymisation is effective?, Information Commissioner's Office (UK). Checked 25 September 2026.
- NIST SP 800-188: De-Identifying Government Datasets, National Institute of Standards and Technology, September 2023. Checked 25 September 2026.
- How to redact a PDF, PDF Expert (Readdle). Checked 17 September 2026.
- Adobe Acrobat plans and pricing, Adobe. Checked 17 September 2026.