I think these links might explain what’s happened. The ACT Government did the same thing a few years back.

http://blogs.adobe.com/security/2009/12/how_to_properly_redact_pdf_fil.html
http://blogs.adobe.com/security/2010/04/are_you_redacting_pdf_document.html

To redact a digital document you need to understand a few things:

1) Digital documents can consist of layers so although what you see looks like you scribbled over the top of something it could be that you scribbled on a new layer – as a result the old layer still exists intact, and although the visual representation might look like what’s underneath is hidden, to a computer it is still their plain as day.

2) With all digital documents there is METADATA http://soft-xpansion.eu/files/cc/Metadata.pdf – so if you create a document on your device, chances are details about you were automatically added into this metadata and will still be there even if you made the entire content of the document blank. You can use this tool to read it:

http://www.extractmetadata.com/

For example if you download and check this document http://fixhepc.com/images/coa/NMR-spectra-of-sofosbuvir.pdf

You will see

Result

Mimetype application/pdf
Title Reports template
Author name National Measurement Institute
Created by software Microsoft® Word 2010
Produced by software Microsoft® Word 2010
Page count 24
Format PDF 1.5
Creation date 20150925095622+10'00'
Modification date 20150925095622+10'00'
Mimetype application/pdf

If you check some of the other documents here: http://fixhepc.com/blog/item/16-testing-provisions-patient-safety.html

You will find for example this for the document: http://fixhepc.com/images/coa/NMI-NATA-Sofosbuvir-Certification.pdf

Result

Mimetype application/pdf
Title Analysis report template
Subject Steroid RMs analysed by GC-FID
Author name PSRM-NARL
Created by software Microsoft® Word 2010
Produced by software Microsoft® Word 2010
Page count 3
Format PDF 1.5
Creation date 20151007171208+11'00'
Modification date 20151007171208+11'00'
Mimetype application/pdf

Which tells us that NMI used a Template and that it was probably a document called “Steroid RMs analysed by GC-FID”.

3) Ever wonder how the “Undo” button works?

The undo button on (say) word works like this. For each change a “note” is added saying “user changed this”.

The version you see represents the original + all the changes you have made since the last “Save As”.

So if you send a Word document that has not had a “Save As” for a while the recipient will be able to use the back button to read previous versions.

“Save As” flattens the document – combining all the changes into one fresh document that has the “Undo” button disabled simply because all the changes got incorporated and the change notes were deleted.

Graphics programs that have layers have a function called “Flatten” then adds all the layers together to produce a single image, however Graphics Program, Word Doc, or PDF there will still be Metadata in there.

Please take steps to protect your privacy. Although there is nothing to be ashamed of for having contracted an infectious disease, if you don’t want to have people find out your name make sure it’s not there to be found…..