Hacker News Reader

As an example, take a photo with a relatively new digital camera and open the JPG up with an EXIF reader. In all likelihood, you'll see GPS coordinates, the exact time you took the picture, along with the unique identifier of your camera.

See http://en.wikipedia.org/wiki/Exchangeable_image_file_format#....

View on HN

Even if you scrub the EXIF data (which you absolutely should do of course) remember that it's likely possible to identify if you took a particular photograph with a particular device.

That isn't a danger that you'll be identified from the photo, but it prevents plausible denial at a later date.

https://www.schneier.com/blog/archives/2006/04/digital_camer...

This can be easily overcome by adding random noise.

Random noise only means you need more samples; it can't block a consistent pattern.

You can add a consistent random pattern.

You need a method that can't be distinguished from the native pattern. How much trust do you want to put in your algorithm being invulnerable to future analysis?

blur and threshold.

That's surely not what kijin was referring to; that can easily be stripped out. Rather there's the problem of being able to determine location purely from the picture itself -- a picture contains a lot more information than just the particular thing you intend to point out in it.

Reply on news.ycombinator.com