A redacted PDF is a file someone has drawn black boxes on and sent out. Nobody checks what is under the boxes, because there is no everyday tool for it.
Often the text is still there. On 8 January 2019, Paul Manafort’s lawyers filed a brief with black boxes over several paragraphs. Reporters selected the boxed text, pasted it into a text editor, and read it. On 29 January 2021 the European Commission published its redacted AstraZeneca vaccine contract; the page text was blacked out, but the PDF’s bookmarks still held the first line of every clause, price included.
Those are the famous cases. The ordinary ones don’t make the news: a claim file emailed to the other side, a tender with a competitor’s rate still in the text, a staff file sent to a regulator with the whited-out salary still there for search to find.
Why it happens
A PDF page is a list of drawing instructions, run in order. “Draw this text. Now draw a black rectangle here.” The rectangle is drawn last, so it is what you see. The text instruction before it is still in the file.
So a redaction can fail in several ways, and every one of them looks right on screen:
- The redaction was marked in the viewer but never applied.
- A filled rectangle was drawn over the text.
- An image was pasted over the text.
- A white box was drawn and new text typed on top. Both texts are in the file.
- Pen strokes were scribbled over the text.
- The text was removed from the page but not from the document’s metadata.
A person checking by eye checks the picture. All six pass that check.
peter@docs2info.com
