.@ Tony Finch – blog

In Zooko's original essay he described the trade-off as "Decentralized, Secure, Human-Meaningful: Choose Two". The problem with this is that these properties are not independent: a central naming authority can rescind or re-assign a name, which is effectively an attack on the association between the name and its referent. So not decentralised implies not secure.

Paul "ciphergoth" Crowley talks about Zooko's Tetrahedron which is a four-way tradeoff between "Memorable, Decentralized, Specific, Transferable". In his essay he gives a weak meaning to "Specific", such that security requires decentralisation and specificity but is not implied by them. However it seems that the Tahoe-LAFS developers use "Specific" with the same meaning that others give to "Secure" - which leads to the same lack of independence as Zooko's version.

In Marc Stiegler's essay on petnames the trichotomy is described as "Memorable, Global, Securely Unique" which can each be chosen independently. This is the version I prefer, though I might use different terms for the concepts - perhaps "User-friendly, Transferable, Secure".