Editing Distributed hash table (section)

== Security ==

Because of the decentralization, fault tolerance, and scalability of DHTs, they are inherently more resilient against a hostile attacker than a centralized system.{{Vague|date=June 2016}}

Open systems for [[distributed data storage]] that are robust against massive hostile attackers are feasible.<ref>
Baruch Awerbuch, Christian Scheideler.
"Towards a scalable and robust DHT".
2006.
{{doi|10.1145/1148109.1148163}}
</ref>

A DHT system that is carefully designed to have [[Byzantine fault tolerance]] can defend against a security weakness, known as the [[Sybil attack]], which affects most current DHT designs.<ref>Maxwell Young; Aniket Kate; Ian Goldberg; Martin Karsten.
[http://www.cypherpunks.ca/~iang/pubs/robustMessagePassing.pdf "Practical Robust Communication in DHTs Tolerating a Byzantine Adversary"] {{Webarchive|url=https://web.archive.org/web/20160722030852/http://www.cypherpunks.ca/~iang/pubs/robustMessagePassing.pdf |date=2016-07-22 }}.</ref><ref>
Natalya Fedotova; Giordano Orzetti; Luca Veltri; Alessandro Zaccagnini.
"Byzantine agreement for reputation management in DHT-based peer-to-peer networks".
{{doi|10.1109/ICTEL.2008.4652638}}
</ref> Whanau is a DHT designed to be resistant to Sybil attacks.<ref>Whanau: A Sybil-proof Distributed Hash Table
https://pdos.csail.mit.edu/papers/whanau-nsdi10.pdf {{Webarchive|url=https://web.archive.org/web/20220125025128/https://pdos.csail.mit.edu/papers/whanau-nsdi10.pdf |date=2022-01-25 }}</ref>

Petar Maymounkov, one of the original authors of [[Kademlia]], has proposed a way to circumvent the weakness to the Sybil attack by incorporating social trust relationships into the system design.<ref>{{Cite book |last=Lesniewski-Laas |first=Chris |chapter=A Sybil-proof one-hop DHT |date=2008-04-01 |title=Proceedings of the 1st Workshop on Social Network Systems |chapter-url=https://dl.acm.org/doi/10.1145/1435497.1435501 |series=SocialNets '08 |location=New York, NY, USA |publisher=Association for Computing Machinery |pages=19–24 |doi=10.1145/1435497.1435501 |isbn=978-1-60558-124-8}}</ref> The new system, codenamed Tonika or also known by its domain name as 5ttt, is based on an algorithm design known as "electric routing" and co-authored with the mathematician Jonathan Kelner.<ref>{{Cite journal |last1=Kelner |first1=Jonathan |last2=Maymounkov |first2=Petar |date=2011-07-22 |title=Electric routing and concurrent flow cutting |url=https://linkinghub.elsevier.com/retrieve/pii/S0304397510003476 |journal=Theoretical Computer Science |series=Algorithms and Computation |volume=412 |issue=32 |pages=4123–4135 |doi=10.1016/j.tcs.2010.06.013 |issn=0304-3975|hdl=1721.1/71604 |hdl-access=free }}</ref> Maymounkov has now undertaken a comprehensive implementation effort of this new system. However, research into effective defences against Sybil attacks is generally considered an open question, and wide variety of potential defences are proposed every year in top security research conferences.{{Citation needed|date=May 2020}}