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04 — Trusted setup · Ceremony approach

snarkjs (powersoftau + zkey)

Phase 1 and phase 2 tooling

In one paragraph

snarkjs (powersoftau + zkey): Phase 1 and phase 2 tooling. The de facto toolchain for Circom-based Groth16 and PLONK projects, covering both the universal phase and the circuit-specific phase, on BN254 and BLS12-381. Maturity: Production-used, actively maintained. Maintained by: iden3 (Polygon ID lineage), open source. Choose it when: Circom-based Groth16 and PLONK teams, and anyone consuming .ptau artefacts from Perpetual Powers of Tau.

By MarketComp Updated v1.3 About the authors Changelog

What it is

The de facto toolchain for Circom-based Groth16 and PLONK projects, covering both the universal phase and the circuit-specific phase, on BN254 and BLS12-381. powersoftau verify validates the full chain of embedded public keys, not merely hash continuity.

Strengths and tradeoffs

Strengths
  • Widest ecosystem support and the largest body of published ceremony instructions written against it
  • Verification checks the cryptographic contribution chain, not just file hashes
  • Runs in Node and in browsers, lowering the barrier for independent contributors
  • Consumes widely mirrored .ptau artefacts directly, so phase-1 reuse is a download
Tradeoffs
  • JavaScript/WASM performance and memory limits make very large powers awkward
  • The non-interactive entropy flag is a footgun: a literal string in a CI script produces a contribution with effectively no secret
  • Correct usage is a process, not a command — nothing prevents shipping a key with zero phase-2 contributions

Choose it whenCircom-based Groth16 and PLONK teams, and anyone consuming .ptau artefacts from Perpetual Powers of Tau.

Maintained implementations

iden3 (Polygon ID lineage), open source

Maturity: Production-used, actively maintained · License: GPL-3.0 · github.com ↗

How to decide
Other ceremony approaches in §04
Avoid the setup entirely: transparent proof systemsgnark mpcsetupCoordinated phase-2 ceremony platformsSequencer-mediated large public ceremonyCoordinatorless and on-chain ceremonies

Sources cited on this page · 2

  1. snarkjs — powersoftau and zkey commands, supported curvestool
  2. ptau-deserializer — converts snarkjs phase-1 output for use with gnarktool

All 42 sources for §04 are listed on the section page →

Cite this page 
MarketComp (2026). snarkjs (powersoftau + zkey). The ZK Field Manual (Version 1.3). MarketComp. https://zkpick.com/ceremony/snarkjs/
@misc{zkfieldmanual-snarkjs-powersoftau-zkey,
  title        = {snarkjs (powersoftau + zkey) — The ZK Field Manual},
  author       = {MarketComp},
  year         = {2026},
  version      = {1.3},
  howpublished = {\url{https://zkpick.com/ceremony/snarkjs/}},
  note         = {Accessed: YYYY-MM-DD}
}