PDF manipulation is often invisible to humans: incremental updates, object rewrites, and image re-saves can all change meaning while keeping the document “looking” identical.
Signals we extract
- Incremental update chains (multiple revisions)
- XRef repairs and rebuild artefacts
- Image re-encoding ladders (e.g., copy-paste flattening)
- Metadata plausibility (timestamps, producers, tools)
When evidence is weak or conflicting, CanonProof may return INDETERMINATE — with an explanation of what limited confidence.