Public Lab Research note

Proofmode + Open Camera

by imvec | February 20, 2018 12:24 20 Feb 12:24 | #15786 | #15786

What we want to do

Add verifiability to the pictures and videos obtained in the course of an environmental investigation using mobile phones and the combination of two apps: Proofmode and Open Camera


Guardian Project and Witness have developed Proofmode, an Android only application to increase the verifiability of the images obtained using mobile phones. On the technical front, what the app is doing is automatically generating an OpenPGP key for this installed instance of the app itself, and using that to automatically sign all photos and videos at time of capture. A sha256 hash is also generated, and combined with a snapshot of all available device sensor data, such as GPS location, wifi and mobile networks, altitude, device language, hardware type, and more. This is also signed, and stored with the media. All of this happens with no noticeable impact on battery life or performance, every time the user takes a photo or video.

Open Camera

Open Cámera is an Android only app developed by Mark Harman that has some technical features that help us to increase the verifiability of our images. The app can make use of the Android2API, enabling a mobile phone to capture images in RAW format. The RAW/DNG format is considered nowadays the "negative" of a digital picture. The interesting thing is that RAW format pictures are not modifiable. Every modification we make to the file using a RAW developing software like Darktable, UFraw or Lightroom is registered in a .xml sidecar file. The result is always having the original shoot. Toghether with this feature you can shoot jpg+raw combined pictures, geotag, stamp... a great camera for your mobile phone, free and open source.

Combining both apps

So, using open camera to take RAW format pictures and having the Proofmode running on the background gives us RAW format pictures, signed with an OpenPGP key, with it's bits counted with a sha256 hash and all our mobile phone's sensors data added to the pictures as metadata. This is not the final solution to the question of verifiability but certainly adds some layers of it to our investigations.

Next Steps

Make a step by step guide of the Open Camera features.

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Awesome! Did this used to be called CameraV or is that a parallel project?

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Hi jeff, that's almost correct. Talking to Jackie Z from Witness, she told they're discontinuing the CameraV project and focusing on the Proofmode. Except for the encrypted storage it works the same way in relation to the pgp signing the sensors data added a pictures metadata. The advantages are that it's really lightweight and always working on the background. You take pictures with your regular camera and then, if you want, you can share them with or without the metadata and the hash in a sidecar file. Pretty awesome combining with RAW pictures ;)

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Linking back to this post by @stevie on documenting a site photographically!

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