The Cost of Stability: Deanonymizing Onion Services Long-Lived Introduction Circuits
An intersection attack on Tor's long-lived introduction circuits located a test onion service in a median 2.2 hours.
Tor client circuits usually last about 10 minutes, but onion-service introduction circuits remain fixed for 18 to 24 hours. The paper presents an intersection attack in which an adaptive adversary observes one relay at a time and uses that longevity to locate an onion service. In nine end-to-end tests on the live Tor network against a self-operated service carrying third-party traffic, the attack reconstructed the full circuit every time, with a median time of 2.2 hours. The authors propose periodically rebuilding internal introduction circuits without changing publicly advertised information.
- Onion service introduction circuits stay fixed for 18 to 24 hours.
- An adversary watching one relay at a time can intersect those circuits.
- Nine live-network runs against the authors' own service rebuilt every circuit.
- Median reconstruction time was 2.2 hours.
- Proposed fix periodically rebuilds internal introduction circuits.
From the original article
1 min read at arxiv.orgTor is a widely used anonymity network that provides network privacy by routing client communications through a sequence of relays to their destinations. An adversary observing a single Tor relay cannot readily link clients to their destinations, as doing so requires identifying the other relays along the client circuit.
By Nicolas Constantinides · arxiv.org
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