Using local AI with confidential business documents
A controlled document workflow from approved folder to local index, answer, review, backup and deletion.
The security boundary is the whole document path—not merely the place where the language model runs.
- 01Map source files, extracted text, embeddings, prompts, outputs, logs and backups.
- 02A network share is not automatically an approved ingestion boundary.
- 03Restore and deletion tests matter as much as encryption claims.
Follow every copy the workflow creates.
Document AI commonly extracts text, divides it into chunks, creates embeddings, stores an index and records conversation history. Even when the original PDF stays in one folder, these derived representations may contain confidential information and need the same governance attention.
The data map should include temporary files, OCR output, browser downloads, application logs, backup archives and any diagnostics attached to a support request. ‘The model is local’ answers only one line of that map.
Use an approved staging folder.
Pointing an indexer at an entire file server is convenient and usually excessive. Start with a named folder whose owner, access group, document classes and retention period are known. Copy or synchronise only material required for the defined workload.
New documents should enter through a repeatable check: file type, malware scan, duplicate handling, OCR quality, access classification and index status. Failed extraction should be visible rather than silently producing incomplete answers.
- —Separate staging, indexed and rejected states.
- —Record file version and last indexed time.
- —Preserve a source link or stable identifier for every answer citation.
Treat generated text as a draft with provenance.
A useful interface separates retrieved evidence from generated interpretation. Users should be able to open the supporting passage, see which file version was indexed and identify when the answer relies on general model knowledge instead.
Before generated material leaves the organisation, a named person should verify facts, numbers, recipients, commitments and confidentiality. The review step should be part of the workflow, not an assumption in training material.
Back up, restore and delete the whole workspace.
An encrypted export is useful only if another authorised machine can restore it and the recovery key is available under a documented procedure. Test restoration before relying on the archive.
Deletion must cover source copies, extracted text, embeddings, conversations, caches and backups according to the organisation’s retention policy. Where immediate backup deletion is impractical, record the expiry path and ensure deleted data does not return during restore.
Sources and method
Primary and technical sources consulted for this article. Access dates are recorded because model documentation and policy guidance change.
- 01IT-Grundschutz CompendiumGerman Federal Office for Information Security (BSI) · accessed 2026-08-09
- 02General Data Protection RegulationEUR-Lex · accessed 2026-08-09
- 03OWASP Top 10 for Large Language Model ApplicationsOWASP Foundation · accessed 2026-08-09
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