plonk


tl; dr


  • introduced in 2019, plonk stands for "permutations over lagrange-bases for ecumenical noninteractive arguments of knowledge", brining enhancements to the usability of zkps by giving a universal fully-succinct zk-SNARK with significantly improved prover run time compared to fully-succinct sonic.
  • while plonk still requires a trusted setup procedure similar to snarks, but it's universal and updateable trusted setup, meaning:
    • instead of there being one separate trusted setup for every program to be proved, there is one single trusted setup for the whole scheme.
    • there is a way for multiple parties to participate in the trsuted setup such that it's secure as long as any one of them is honest, and this multi-party procedure is fully sequential (polynomial commitment, in this case, kate).
  • there are two types of constraints:
    • gate constraints (equations between wires attached to the same gate, e.g., a1 * b1 = c1).
    • copy constraints (claims about equality of different wires anywhere in the circuit, e.g., ao = a1)
  • polynomial commitments is a short object that represents a polynomial, allowing evaluations verification without needing all the data in the polynomial.
    • if someone gives you a commitment representing c they can give you a proof that can convince you, for some specific z, what the value of P(z).
    • a commitment to a degree-d polynomial is made by multiplying each of the first d+1 points in the proving key by the corresponding coefficient in the polynomial, and adding the results together, providing an evaluation of that polynomial at s without knowing s.



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