GUIDE · REDACTION

How to permanently redact a PDF, so the text is really gone

Many leaked documents were redacted with a black rectangle drawn on top of the text. Anyone could select the text underneath and copy it. Real redaction removes what is under the box, and more.

Why a black box is not redaction

A PDF page is built in layers. Drawing a black rectangle, or highlighting text in black, adds a shape on top; the text is still in the file underneath. Anyone can select it, copy it, or extract it with a text tool. The same applies to covering text with an image or a comment.

Real redaction removes what is under the box from the file itself. It should also deal with the places text hides outside the page:

• Document properties: title, author, subject, keywords
• Annotations and comments
• Form fields and their values
• Bookmarks (the outline) and link targets
• Attachments embedded in the PDF

How to check a redaction

1. Open the redacted PDF in any viewer.
2. Press Ctrl+A (or Cmd+A) on a redacted page, copy, and paste into a text editor.
3. Search the pasted text, and the PDF itself, for a word you redacted.
4. Check the document properties for names.

If the word is there, the redaction did not work, whatever the page looks like.

Redact a PDF with Inkmark

1. Open Inkmark, drop the PDF in and switch to Redact.
2. Choose what to look for: Social Security numbers, EINs and tax IDs, card numbers, IBANs, ABA routing numbers, labelled account numbers, emails, phone numbers, labelled dates of birth or all dates, plus your own search terms and regular expressions.
3. Review the results, grouped by category. Each match is either will be redacted or kept; change any of them on the list or on the page.
4. Draw boxes by hand for anything else, including signatures, photos and scanned pages.
5. Turn on Preview redacted to see the result, then export. The review screen lists how many items will be removed on which pages before you download.

What happens on export

Each page with a redaction is rendered to a high-resolution image with the boxes burned in, so the pixels under the boxes are gone. Text outside the boxes is put back as an invisible layer, so the rest of the page stays searchable and selectable. Annotations, form fields, attachments, bookmarks, link targets and document metadata are removed. Pages without redactions are kept as they were. Your original file is not changed.

Inkmark does not run OCR. On scanned pages it cannot suggest matches, so draw the boxes yourself.

Before you send a redacted PDF

• Review every suggestion; automatic detection can miss unusual formats.
• Run the copy-and-search check above on the exported file.
• Look at images and scanned pages yourself.
• Keep the original somewhere safe and separate from the redacted copy.