How can I keep a file from revealing my personal details?

Updated:July 2016

Metadata is literally "information about the information." Most computer files contain some information about how they were made, when, where and who by. Know what your file’s data can reveal about you, and how to stop it.

When we talk about a ‘file’ it could be a text document, image, video, spreadsheet, piece of audio, a folder, software, or anything on your computer. Every time you create, download or edit something, the file can record important personal information within itself. This is called metadata. Sometimes it's useful: it helps keep a record of what's been happening with the file. For that same reason, it can also be potentially risky.

GET STARTED:

  1. How Metadata works
  2. Start with the simplest solution
  3. Control your work environment
  4. Software and phone apps

 


How metadata works

Your files can store information such as your name or initials, the name of your company or organisation, personalised information about your computer. It can also hold details about networks or other computers where it's been copied from, the names of other editors, and editing history. Images and video contain a lot of data about the kinds of cameras were used, time, date, and sometimes the location that the image or video was created.

How can I keep a file from revealing my personal details?

Removing a confidential file's metadata protects your privacy as well as identifying details about your source.
Try it yourself: Take an image you're not worried about and upload it to exifdata.com and see what it tells you.

Controlling metadata isn't just for a freelancer's protection. Often a journalist receives sensitive documents from a source, and may want to share the source material with editors and others to verify the material, or back up their work. Removing the meta data can help protect a confidential informant's identity, and give you plausible deniability if you need it.
 


The simple solution: Use hard copies

One obvious and simple solution is to print documents or images and share them by hand. Alternately, if you need to send them electronically, you may want to print the pages and then use a scanner on another machine (that's not yours) to put them back in digital format, but without the meta data of the original. These will still contain some information, but won't have the history of the original files.

This won't work many kinds of files  in our age of multimedia. If you can, show video or audio files in person, but don't leave a copy behind. If you can't do that, then you may need to take some further steps, described below.
 


Control your work environment

If you're dealing with particularly sensitive information, you may not want to use the computer you usually use for creating, editing and handling them. Your computer often contains personal information about you, and this can inform the metadata of files.

Use a different machine not associated with you. Even when doing this, you still may want to check the file's properties to see what's been recorded. For some basic information, this is as easy as right-clicking on the file and selecting to "view properties." For other files you can run software that will look up a lot of telling details.
 


Meta inspecting and editing software

There are many ways to check, edit or limit the information stored within a file’s metadata. There are programs that can do some of this for you, but it’s an area where your operating system and the kinds of files you're working with can limit your options. ExifTool,for example, is an extremely powerful option that works on all PC platforms. The downside is that it requires a decent amount of comfort using your computer’s terminal. Other software is a bit more user friendly, but you'll need to pick the one that's best suited for the kind of file you're dealing with.

SOME OF THE OPTIONS:

  • Multiple file types (Linux): MAT (Metadata Anonymization Toolkit) is an incredibly simple program for Linux computers that covers a lot of popular file formats, and even some less used ones. It's not much of a meta inspector, but has a very basic interface to remove a file's history. MAT is free, open source and supported by the Tor project.
  • Microsoft Office documents (Windows): Use Document Inspector to destroy metadata relating to different comments, revisions, edits and annotations, as well as document properties and personal information, when using Microsoft Word.
  • PDF files (Linux): PDFMod  is a useful programme for Linux that allows users to alter or delete metadata stored within PDFs.
  • Image files (Chrome, Firefox): Exif Viewer is browser-based program that gives you information about what information is in an image file, and there are version for both Firefox and Chrome. There's also a version for iPhone.
  • Smartphone camera (Android): Use ObscuraCam when taking mobile phone images or video. ObscuraCam removes all personal data from the file. This program also provides the ability to obscure the faces of people within the image.

Image credit: Screen grab by Craig Nagy.

Created: July 2013

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