Thread by @bpreneel1

I co-authored a new open letter signed by more than 270 scientists from 33 countries warning for the risks of the modified CSAM (child sexual abuse) regulation proposed by the Belgian presidency. #chatcontrol

A🧵1/10csa-scientist-open-letter.org

Two major changes: target detection based on risk and require more than one hit to reduce false positives will not have meaningful impact on protection of fundamental rights. 2/10

So-called targeted detection will affect billions of users on widely used apps such as WhatsApp and Signal. 3/10

Detection of information in content prior to encryption cannot be reconciled with the essence of end-to-end encryption. Major risk for abuse by undemocratic regimes. 4/10

The technology will fail to achieve its claimed goals for various reasons (insecure perceptual hash functions, huge number of false positives, framing of innocent users, easy to bypass). 5/10

Chilling effect on teenagers. 6/10

There is no practical and widely deployed solution yet for privacy friendly age verification; not clear that eIDAS 2.0 will solve it given that unlinkability protection in the future digital identity wallet is optional. 7/10

Unclear why some governments keep pushing for this mass surveillance approach rather than focusing on prevention of sexual abuse of children. 8/10

Overall lack of transparency in the process and failure of decision makers to openly engage with academic community and civil society on the problem. 9/10

Likely part of the global war on encryption ("going dark" working party) with as main target terrorism, organized crime and (in some countries) political opposition and human rights advocates. But CSAM plays to emotions thus easier to sell to broader public 10/10