How to verify that a PDF redaction is clean
Short answer: To check that a redaction is clean, go through six areas one by one: page text, hidden text layers, scan pixels, internal file data, metadata and attachments, and earlier versions. EnjoyPDF runs these checks automatically after saving, and you can repeat them yourself with the methods on this page.
PDF Text Replacer automatic checks
After saving with secure redaction, the software reopens the output file and checks it item by item against the removed content:
| Check | How |
|---|---|
| Page text and hidden text layers | Extract all text and search for the removed content |
| Scan image pixels | Recognize the processed areas again |
| Strings and streams in file objects | Search the internal file data in several encodings |
| Document info and XMP metadata | Check that they are empty |
| Annotations, forms, attachments, scripts, bookmarks | Check whether any exist |
| EXIF / XMP / comments embedded in images | Check the JPEG segments |
| JBIG2 shared symbol dictionaries | Warn when present |
| Earlier versions | Check that the file has only one version |
The removed content is used for comparison only in memory and is not written to the report. Results go into the residue check section of the operation record (manifest.json), which you can view with the operation record checker.
Check it yourself
- Copy and paste: select all and copy in two different PDF viewers, paste into Notepad and search.
- Search: search the viewer for part of the removed content, such as the last six digits of an ID number.
- Properties: look at the title, author, subject and keywords in the file properties.
- Attachments and comments: confirm that the viewer’s attachments panel and comments panel are empty.
- Zoom in on images: zoom scans to 400% and look for leftover strokes around the covered areas.
When a check fails
The save banner marks the failed items. Common causes are text over a complex background in that area, or an image shared by several pages in the file. You can enlarge the redaction area and process the file again, or contact us and attach the operation record (it does not contain the original text).
FAQ
What does a JBIG2 notice from the automatic check mean?
JBIG2 is a black-and-white image compression method that can share a glyph dictionary across pages. When it appears, EnjoyPDF only gives a warning and does not count it as a failure. We recommend spot-checking that file by hand.
If all automatic checks pass, do I still need to look manually?
A spot check is recommended. The automatic checks confirm the original text cannot be recovered from the file, but whether everything that should be removed was found depends on the types and keywords you selected.