In early January 2019, a high profile case of “Redaction Fail” made the headlines when it was revealed that the redacted material could still be read if copied and pasted into a word processor. My initial reaction was of concern, because my first thought was that the redaction feature in Adobe Acrobat had a serious drawback. However, this was soon put to rest once I viewed the actual document in question, and realised that Acrobat’s redaction feature had not been used, but another low-tech method was used instead.
Low-tech method 1: Highlight
In Microsoft Word, it’s easy to change the highlighter colour to black to act as a redaction. Similarly, Adobe InDesign has a similar feature where an underline can be created that is the same colour as the text and adjusting the height of the line to the top of the ascender to the bottom of the descender.
Looks great on screen, and looks great on a PDF.
Be assured though that this is NOT REDACTED. I know this because I can reveal what was written in several ways:
- By highlighting the text and copying into any text editor;
- By using an accessibility feature that will allow the line (or page) to be read back
- In Acrobat Professional, using the Edit feature to change the colour of the type
- Editing the PDF with the Enfocus Pitstop plug-in in a similar fashion to the last method, or even remove the redaction itself or view the type under the redaction using the wireframe view.
- By highlighting the text, opening the tags panel and selecting Find Tag from Selection
- By highlighting the text, opening the content panel and looking up the content by its page location
- Via the print production tools in Acrobat Professional, go to the output preview and in the Show portion of the dialog box, select Text from the dropdown
(The above method can be circumvented if the redaction character style has a type fill of [None] and the underline coloured [Black]).
To be fair, no security settings had been applied to this test file. If I apply password security so that copying, pasting and accessibility is off, the last three methods can still be employed to see this text, albeit with many options greyed out:
Low-tech method 2: Redact Font
Fonts (such as the redacted font by David Walsh) give the type a redacted look without the need to create a highlighter-style effect.
Again, rest assured that this document is NOT REDACTED.
Park the fact that the copy has now reflowed after the style has been applied, many of the previous methods can still be employed to read this text.
Yes, there is also the drastic action of employing this technique, adding security AND converting all text to outlines using a method described over at InDesignSecrets, but doing so will make a PDF that is:
- Unsearchable and unprintable;
- Has no accessibility features;
- Involves manipulating the original artwork, rather than a file that has to have redactions applied.
If you need to redact the file, use Adobe Acrobat’s Redact feature, and make sure to read the instructions to be sure that is being used properly.
The instructions on the Adobe Acrobat help site for using this feature are quite useful.
A related redaction warning
If photographs also need to be redacted, note that if unredacted versions of the images exist online, chances are that Google’s Image search or Tineye may be able to find the unredacted originals.
Take the following image that was used on this site two articles ago. I’ve done a basic redaction our faces and run the redacted image through exifpurge to remove any metadata.
If I drag and drop this image into Google’s image search, it is able to find the unredacted versions of this photo that are currently online:
While this example was a light-hearted example, much more serious examples can be found via ABC Australia’s Media Watch programme.