[kinofcain]

Back in the '90s some government agency released a redacted report where someone had gone in and drawn black boxes in the PDF file, but the full text was of course still in the underlying data and people were able to get at it relatively easily.

EDIT: apparently this has happened repeatedly, according to a quick google search.

No doubt some sort of knee jerk process was put in place to ensure that any digital release of redacted documents must be scans of a physically redacted source.

Sort of like an analog memory hole.