Harm reduction for cryptographic backdoors

We keep hearing from law enforcement and politicians that end-to-end encryption creates safe spaces for child abusers and other terrible people, and counterarguments from information security people that it would be unacceptable to weaken the security of these systems. The debate has kept repeating over the last 30 years.

My latest blog post is a short paper that I presented today at the 14th Workshop on Hot Topics in Privacy Enhancing Technologies (HotPETs 2021). It’s a proposal for a potential compromise: a way of adding a backdoor to end-to-end encrypted communication systems without opening the door to mass surveillance.

You can find it here: https://martin.kleppmann.com/2021/07/16/cryptographic-backdoors-hotpets.html

I expect this is going to be controversial! Constructive responses welcome as always.

— Martin