- Human-meaningful: Meaningful and memorable (low-entropy) names are provided to the users.
- Secure: Any entity in the system can act maliciously, including the majority of the entities or the available computational power.
- Decentralized: There is still only one, unique and specific entity to which a name resolves.
Zooko Wilcox-O'Hearn conjectured that no single kind of name can achieve more than two. For example: DNSSec, offers a secure, human-meaningful naming scheme, but is not secure against compromise by the root; .onion addresses and bitcoin addresses, are secure and decentralized but not human-meaningful; and I2P, uses name translation services which are secure (as they run locally) and provide human-meaningful names - but fail to provide unique entities when used globally in a decentralised network without authorities.
Several systems which exhibit all three properties of Zooko's triangle have now been created, including:
- Computer scientist Nick Szabo' s "Secure Property Titles with Owner Authority" paper illustrated that all three properties can be achieved up to the limits of Byzantine fault tolerance.
- Activist Aaron Swartz described a naming system based on Bitcoin employing Bitcoin's distributed blockchain as a proof-of-work to establish consensus of domain name ownership. These systems remain vulnerable to sybil attacks, but are secure under Byzantine assumptions. Namecoin now implements the concept.
Several platforms implement refutations of Zooko's conjecture, include: Twister (which use the later Aaron Swartz system with a bitcoin-like system), Blockstack (which can run on any blockchain and currently uses Bitcoin), Namecoin (separate blockchain), and Monero OpenAlias.
- Zooko Wilcox-O'Hearn. "Names: Decentralized, Secure, Human-Meaningful: Choose Two". Archived from the original on 2001-10-20.
- Nick Szabo, Secure Property Titles, 1998
- Aaron Swartz, Squaring the Triangle: Secure, Decentralized, Human-Readable Names, Aaron Swartz, January 6, 2011
- Dan Kaminsky, Spelunking the Triangle: Exploring Aaron Swartz’s Take On Zooko’s Triangle, January 13, 2011
- Monero core team (2014-09-19). "OpenAlias". Retrieved 2015-02-03.
- Zooko Wilcox-O'Hearn, Names: Decentralized, Secure, Human-Meaningful: Choose Two – the essay highlighting this difficulty
- Marc Stiegler, An Introduction to Petname Systems – a clear introduction
- Nick Szabo, Secure Property Titles – argues that all three properties can be achieved up to the limits of Byzantine fault tolerance.
- Bob Wyman, The Persistence of Identity: Updating Zooko's Pyramid
- Paul Crowley, Squaring Zooko's Triangle
- Aaron Swartz, Squaring the Triangle using a technique from Bitcoin