December 16, 2005
Redacting PDFs

Redaction, by definition, means removing information from documents. In the old days of paper, xacto knives were used to cut text from the paper and it was then photocopied with a black sheet of paper behind it.

As numerous folks have found out, covering up information in an electronic file is not the same as deleting it.

<SNIP>

There have been numerous cases recently where improper redaction led to accidental disclosures:

* A PDF distributed by the US government contained covered over text that was fully accessible. In this case, the user authored a document in Microsoft Word and used Word's Tables and Borders toolbar to set the background color to black. Thus, black text on a black background which was not visually readable, but does not eliminate the data. When the user converted the document to PDF, a simple search of the document revealed the text. Note here that Acrobat worked as advertised properly preserving every element of the document.