> DoJ explicitly avoids JPEG images in the PDFs probably because they appreciate that JPEGs often contain identifiable information, such as EXIF, IPTC, or XMP metadata

Maybe I'm underestimating the issue at full, but isn't this a very lightweight problem to solve? Is converting the images to lower DPI formats/versions really any easier than just stripping the metadata? Surely the DOJ and similar justice agencies have been aware of and doing this for decades at this point, right?

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DharmaPolice 2 hours ago | parent | next [-]

This is speculation but generally rules like this follow some sort of incident. e.g. Someone responds to a FOI request and accidentally discloses more information than desired due to metadata. So a blanket rule is instituted not to use a particular format.

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originalvichy 4 hours ago | parent | prev [-]

Maybe they know more than we do. It may be possible to tamper with files at a deeper level. I wonder if it is also possible to use some sort of tampered compression algorithm that could mark images much like printers do with paper.

Another guess is that perhaps the step is a part of a multi-step sanitation process, and the last step(s) perform the bitmap operation.

	▲	normalaccess 3 hours ago \| parent [-]
		I'm not sure about computer image generation but you can (relatively) easily fingerprint images generated by digital cameras due to sensor defects. I'll bet there is a similar problem with PC image generation where even without the EXIF data there is probably still too much side channel data leakage.