Tor Launches Proof-of-Work Defense for Onion Services

"We are officially introducing a proof-of-work (PoW) defense for onion services designed to prioritize verified network traffic as a deterrent against denial of service (DoS) attacks with the release of Tor 0.4.8."

Tor Launches Proof-of-Work Defense for Onion Services
  • "Tor's PoW defense is a dynamic and reactive mechanism, remaining dormant under normal use conditions to ensure a seamless user experience, but when an onion service is under stress, the mechanism will prompt incoming client connections to perform a number of successively more complex operations. The onion service will then prioritize these connections based on the effort level demonstrated by the client."
"We believe that the introduction of a proof-of-work mechanism will disincentivize attackers by making large-scale attacks costly and impractical while giving priority to legitimate traffic."
  • Onion Services are encouraged to update to version 0.4.8.

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