References

Last updated on 2025-02-06.

Current and recent research

• Tor Project Research: contains guidelines researching Tor, tech reports and other resources.
• Anonbib - Free Haven's Selected Papers in Anonymity has recent and past research on Tor, including Onion Services.

Curated list of current recent research

Highlights from the Anonbib:

• 2020:
  • Bypassing Tor Exit Blocking with Exit Bridge Onion Services (HebTor)
• 2024:
  • A Study of Deanonymization Attacks of Onion Services (PDF).
  • Onion Services in the Wild: A Study of Deanonymization Attacks

Selected papers (still) not indexed on Tor Project Research neither in the Anonbib:

• 2018:
  • How Do Tor Users Interact with Onion Services? - sec18-onion-services.pdf:
    • USENIX Security '18 - How Do Tor Users Interact With Onion Services? - YouTube
• 2021:
  • On the state of V3 onion services | Proceedings of the ACM SIGCOMM 2021 Workshop on Free and Open Communications on the Internet:
    • V3 onion services usage | The Tor Project
• 2024:
  • HSDirSniper: A New Attack Exploiting Vulnerabilities in Tor's Hidden Service Directories | Proceedings of the ACM Web Conference 2024, disclosing an issue further mitigated on C Tor 0.4.8.14.

Historical

Historical research:

• The Once and Future Onion: includes a historic overview of Onion Services technology.
• Onion Routing: the onion-router.net site formerly hosted at the Center for High Assurance Computer Systems of the U.S. Naval Research Laboratory (NRL). It primarily covers the work done at NRL during the first decade of onion routing and reflects the onion-router.net site roughly as it existed circa 2005. As a historical site it may contain dead external links and other signs of age.
• Anonbib also goes back since 1977, listing the most relevant papers that lead to Onion Services development.

Historical highlights from the Anonbib:

• 2006:
  • Locating Hidden Servers
  • Valet Services: Improving Hidden Servers with a Personal Touch
• 2007:
  • Improving Efficiency and Simplicity of Tor circuit establishment and hidden services
• 2008:
  • Performance Measurements and Statistics of Tor Hidden Services
• 2009:
  • Performance Measurements of Tor Hidden Services in Low-Bandwidth Access Networks

Historical articles:

• 2013:
  • Hidden Services need some love | The Tor Project, covering:
    • Scaling and performance.
    • DoS protections.
    • Attacks on HSDirs.
    • Recommends the use of "Encrypted Services" instead of Exit Enclaves.
• 2014:
  • Facebook, hidden services, and https certs | The Tor Project, covering:
    • Still pre-v3 services.
    • Discussion on vanity addresses.
    • Discussion about HTTPS certificates for Onion Service websites.
    • What still needs to be done (from that time perspective).

Related

Although not focused in the Onion Service, other references might be relevant, like those covering anti-censorship:

• CensorBib: an archive of selected academic research papers on Internet censorship.