Remove PrivacyBlur

It seems it is no longer secure to blur face.
It is possible to use image processing techniques to unblur or reconstruct a face, and facial recognition technology may still be able to identify a person even if their face is blurred (this is also highly depends on the blur algorithm).

References:
https://scholarworks.uark.edu/cgi/viewcontent.cgi?article=1067&context=csceuht

Instead, blacking/whiting something is a much better option for anonymity. This can easily be done via each device’s built-in annotation feature or through the app that use to share the image like Signal which remove the need for a separate application like Privacy Blur and Pocket Paint.

I’m reviving this because I noticed another reason that makes further recommendation of PrivacyBlur questionable: Updates, or the lack thereof.

PrivacyBlur is available for Google Play Store, F-Droid and Apple App Store. There’s also a Website and a GitHub Repo with the last commit being made on Feb 15 2022.

This is of course a very long time to go by without activity.
Frankly, it’s been abandoned for at least 19 months.

I said at least because the iOS version was dropped even before that:

  • v2.1.6-full from Jan 10 2022 was the last update on Play Store
  • v2.1.6-foss managed to find its way to F-Droid on Jan 18 2022
  • Meanwhile the last update in the App Store was v2.1.2 from Jun 29 2021

That was more than two years or about 28 months ago.

TLDR We all need to be very careful not to rush this, but it might be time to start rethinking this* recommendation

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Someone should look into this.

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It does appear to be unmaintained, do we have any replacement suggestions?

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it hasn’t been updated in a few years, but ObscuraCam comes to mind. similar face detection software from the guardian project, with multiple options for it including redacting (with solid color, and other options)

The only “maintained” service that comes to my mind is… Signal, since you can take a photo and blur the face or draw in the face to hide it with something like Note to Self

Another method is using the device’s built-in blur tool, but that’s very device-specific. AFAIK, Samsung and Pixels have that capability.

As far as I know this app still works though, I don’t think we should be too quick to remove seemingly unmaintained apps simply because they haven’t been updated in a while. If an OS update breaks PrivacyBlur it may still receive a patch in the future for example, we don’t really know until that happens.

Some of these tools like PrivacyBlur are single-purpose tools which can be “complete” after all. This app only does one thing, it’s not a browser or operating system.

Also, we do already have a warning about blurring text.

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True enough I guess. The only issue can be if apps depend on old API levels it creates a lot of work for developers to catch up when those are deprecated and then eventual removal from Play etc.

I guess we can wait a bit longer.

Also, we do already have a warning about blurring text.

You didn’t check the research paper? It’s not specific to text only, faces too etc.

Being unmaintained is something that was discussed later in the thread, not the initial post by OP. Also dev said it won’t be updated for now Maintaince status? · Issue #91 · MATHEMA-GmbH/privacyblur · GitHub

@dngray AI resistant blurring · Issue #69 · MATHEMA-GmbH/privacyblur · GitHub lol, this is the best way rn, unless someone builds an app that uses a secure algorithm.

You can add the warning to the knowledgebase section.

You should never use blur to redact text in images. If you want to redact text in an image, draw a box over the text. For this, we suggest apps like Pocket Paint.

Also, the target sdk of this aplication influences its security? Because PrivacyBlur targets sdk 30 according to Aurora Store.

Also, is it possible to add a little warning below the PrivacyBlur recommendation? To mention the security issues of blurring your face.

Reading through the linked paper and other resources, I don’t think concrete security issues with face blurring have actually been identified, especially with the pixelate filter (as opposed to gaussian blur) present in this app.

If we want, I’d be fine with amending the existing warning to say:

Blurring is not as secure as simply drawing an opaque box (i.e. a black box) over a portion of an image. You should especially never use blur to redact text in images. For this, we suggest apps like Pocket Paint.

…but not really to say anything about faces specifically.

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Yes, I’m definitely fine with that.

I think it’s generally good to just recommend people to black out things. This is much more secure.

With documents however you should be wary when blocking out words with black bars. I have recently seen a talk (OSINT - How AI fuels disinformation - media.ccc.de) that shows how those words could be predicted pretty accurately. Although if it’s just for personal data that’s completely fine and effective.

what about GitHub - T8RIN/ImageToolbox: 🖼️ Image Toolbox is an powerful picture editor, which can crop, apply filters, add some drawing, erase background, edit EXIF or even create PDF file ?

  • Drawing on Image/Background

Privacy Blur

I don’t know if this is a problem, but the app you linked is much more than just an app to blur faces. You can edit EXIF, erase background, apply filters, crop images, create a PDF file, comparing images, etc… The list goes on…

Nope. They already suggest Pocket Paint which does a lot of things too… ImageToolbox maybe be a better alternative for both PrivacyBlur and Pocket Paint.

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Using LLMs to Unredact Text

https://twitter.com/khoomeik/status/1765373683449893123

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Well the solution to that is a large slab of black text over the whole line, not individual broken up boxes that are exactly the same size as the characters being redacted.

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