LibreOffice PII Anonymization: Writer, Calc, and Impress
Research Source
LibreOffice serves millions of users worldwide, particularly in government, education, and organizations that prefer open-source software. These users process documents containing PII but have no extension or add-in for PII detection and anonymization. Microsoft Office users have the anonym.legal Office Add-in; LibreOffice users have had no equivalent.
Executive Summary
LibreOffice serves millions of government, education, and open-source users who process PII-containing documents. Until now, there has been no PII anonymization extension for LibreOffice.
anonym.legal LibreOffice Extension v1.0.0 provides PII detection and anonymization for Writer (documents), Calc (spreadsheets), and Impress (presentations). Format-preserving processing maintains 7 font properties and 4 paragraph properties.
The Problem: The Open-Source Office PII Gap
Government agencies across Europe mandate LibreOffice for document processing. Educational institutions use it for cost reasons. Open-source advocates use it on principle. All of these users process sensitive documents — citizen records, student data, personnel files, legal contracts. Microsoft Office users can install the anonym.legal Add-in for in-document PII processing. LibreOffice users had no equivalent — they had to copy text to external tools, losing formatting and document structure.
Irreducible truth: Office suite market share does not determine PII processing needs. LibreOffice users have the same PII protection requirements as Microsoft Office users. Platform availability should match user need, not market share.
The Solution: How anonym.legal Addresses This
Writer, Calc, and Impress Support
The extension works across all three LibreOffice applications. Writer processes document text with full paragraph structure. Calc processes cell content with cell-based detection. Impress extracts text from text boxes, shapes, and speaker notes.
Format Preservation
7 font properties preserved: bold (CharWeight), italic (CharPosture), underline (CharUnderline), strikethrough (CharStrikeout), font name (CharFontName), font size (CharHeight), font color (CharColor). 4 paragraph properties preserved: alignment (ParaAdjust), first-line indent, left margin, right margin.
Chunked Processing
Documents are processed in 8,000-character chunks with 400-character overlap to prevent entity splitting across chunk boundaries. Preview dialog shows up to 50 detected entities before processing begins.
Zero-Knowledge Auth
Same Argon2id (64MB, 3 iterations) + XChaCha20-Poly1305 ZK authentication used across all anonym.legal platforms. Preset syncing every 5 minutes. 55-minute session tokens with 7-day credential persistence.
Compliance Mapping
This feature addresses GDPR Article 25 (data protection by design — PII processing available in the office suite users actually use), and government open-source mandates that require LibreOffice compatibility for all document processing tools.
anonym.legal's GDPR, HIPAA, PCI-DSS, ISO 27001 compliance coverage, combined with Hetzner Germany, ISO 27001 hosting, provides documented technical measures organizations can reference in their compliance documentation.
Product Specifications
| Specification | Value |
|---|---|
| Entity Types | 320+ |
| Detection | 3-layer hybrid: Presidio + NLP + Stance classification |
| Test Coverage | 100% (419/419 tests) |
| Languages | 48 |
| Anonymization Methods | Replace, Redact, Mask, Hash (SHA-256/512), Encrypt (AES-256-GCM) |
| Platforms | Web App, Desktop, Office Add-in, Chrome Extension, MCP Server, REST API |
| Pricing | Free €0, Basic €3, Pro €15, Business €29 |
| Hosting | Hetzner Germany, ISO 27001 |
| Compliance | GDPR, HIPAA, PCI-DSS, ISO 27001 |