[somezero]

The paper is simple and readable enough for me to not have to comment. Anyway, The abstract itself says:

> This paper shows that, without a logically centralized authority, Sybil attacks are always possible except under extreme and unrealistic assumptions of resource parity and coordination among entities.

And the proof is a few pages later in a few Lemmas. Note that this paper is where Sybil attacks actually come from, and you can see almost all DHT security papers (eg. Castro’s secure routing paper [1]) assume a CA.

[1] section 3.2 of https://www.cs.rice.edu/~dwallach/pub/osdi2002.pdf