Sat 26 Aug 2023 // 08:31 UTC

https://www.theregister.com/2023/08/26/tor_tweaks_onion_routing_softw
are/

To thwart future debilitating DDoS attacks, Tor developers have been
working on a defense first proposed in April 2020. It just arrived in
Tor version 0.4.8.4 and it relies on a mechanism developed in 1992 by
Moni Naor and Cynthia Dwork as a defense against DoS and spam but
made famous for energy profligacy by Bitcoin: proof-of-work.

Essentially, clients trying to reach .onion services may be asked to
complete small proof-of-work tests. If you're connecting as a legit
user, you shouldn't notice anything. If you're trying to hammer the
project's network of nodes with lots of repeated connections, the
proof-of-work challenges may well hamper your attempts.

If we ever hope to have truly reachable global onion services, we
need to make it harder for attackers to overload the service with
introduction requests," explain Tor contributors George Kadianakis,
Mike Perry, David Goulet, and Tevador in the project outline. "This
proposal achieves this by allowing onion services to specify an
optional dynamic proof-of-work scheme that its clients need to
participate in if they want to get served."

Nomen Nescio <nobody@dizum.com> wrote:

>Sat 26 Aug 2023 // 08:31 UTC
>
>https://www.theregister.com/2023/08/26/tor_tweaks_onion_routing_software/
>
>
>To thwart future debilitating DDoS attacks, Tor developers have been
>working on a defense first proposed in April 2020. It just arrived in
>Tor version 0.4.8.4 and it relies on a mechanism developed in 1992 by
>Moni Naor and Cynthia Dwork as a defense against DoS and spam but
>made famous for energy profligacy by Bitcoin: proof-of-work.
>
>Essentially, clients trying to reach .onion services may be asked to
>complete small proof-of-work tests. If you're connecting as a legit
>user, you shouldn't notice anything. If you're trying to hammer the
>project's network of nodes with lots of repeated connections, the
>proof-of-work challenges may well hamper your attempts.
>
>If we ever hope to have truly reachable global onion services, we
>need to make it harder for attackers to overload the service with
>introduction requests," explain Tor contributors George Kadianakis,
>Mike Perry, David Goulet, and Tevador in the project outline. "This
>proposal achieves this by allowing onion services to specify an
>optional dynamic proof-of-work scheme that its clients need to
>participate in if they want to get served."

The revival of Hashcash!