Finishing Hermez Trusted Setup Ceremony

2 years ago   •   3 min read

By Polygon Hermez

The launch of the Hermez mainnet is around the corner!

After implementing the Poseidon fix, we’re currently finishing up the Trusted Setup Ceremony.

In this article, you’ll find the technical details of the last stage of our Multi-Party Computation Phase.

Finishing the Multi-Party Computation Phase

Following the execution of the Multi-Party Computation (MPC) first and second phases, we are ready to apply a random beacon for extra security.

While this step might not be strictly necessary, we want to strengthen the protocol’s cryptographic integrity before launching the mainnet.

During the last weeks, we have been running phase2 of the Hermez Network trusted setup ceremony. Below are further details about its development.

This phase2 was run on three circuits:

  • circuit_1912_32_256_64: Batch processor of 1912 Txs.
  • circuit_344_32_256_64: Batch processor of 344 Txs.
  • withdraw: Circuit used to withdraw funds.

The last stage of the ceremony was run by seven trusted individuals from the community:

* jordi
* kobigurk
* eduadiez
* thore1234
* josephc
* weijie
* jarradhope

After the contributions, the b2sum of the zkey files resulting from the last contributions are:

b2sum circuit_1912_32_256_64_hez3_0007.zkey

3aceeb98 42ecc5d6 ff0ce9be 184f5b2e
21182fbb e1ba642b f751d799 59d16a95
D996f0d0 4e91b0d9 7606ccdf 557bfb37
0263a05f 48d40932 d45f8b77 3a0e68e0


63fcde7c 5b5a2ee2 abaec90f a02025ad
Eb6559bd 5b318593 b4cec080 daf51996
54ae6f00 0af6cd7e 9393d3a9 0e1a5bfb
3e1d52b7 2a065d9d 65eb8e60 57dbf886


072543ae 5b51b2e7 4ea1ce56 a8afde52
B58ad938 06d595ab 8512880f bb5aa592
Bf765ec5 e2e58948 6d23bd5c d4ca9f88
7eacb995 51779402 c46f25f8 9b506184

You can see more details of the ceremony here.

Before calculating the final zkey file, we will apply a random beacon to the three circuits.

Notice that according to this, a random beacon might not be strictly necessary. Nevertheless, we consider best practice to do so.

For this, we will apply the result of the round 697500 of drand.

Here is the info of the drand chain that will be used:

"public_key":"868f005eb8e6e4ca0a47c8a77ceaa5309a47978a7c71bc5cce96366	b5d7a569937c529eeda66c7293784a9402801af31",
"hash":"8990e7a9aaed2ffed73dbd7092123d6f289930540d7651336225dc172e51	b2ce",

"groupHash":"176f93498eac9ca337150b46d21dd58673ea4e3581185f869672e59	fa4cb390a"

This number is planned to be generated on Sunday March 21st, 20:37:00 UTC.

Once the number is generated, you should be able to find it here:

or here.

To check the correctness of the software generating the number, check here.

You can also use this code to verify it:

Commit used:

The resulting random number, translated to hexadecimal, will be treated as the beaconHash used as the key generation beacon with 2^10 sha256 iterations.

Finally, the last contribution will be generated this way:

With [email protected]:


snarkjs zkey beacon circuit_1912_32_256_60_hez3_0007.zkey circuit_1912_32_256_60_hez3_final.zkey [beaconHash] 10
snarkjs zkey beacon circuit_344_32_256_60_hez3_0007.zkey circuit_344_32_256_60_hez3_final.zkey [beaconHash] 10
snarkjs zkey beacon withdraw_hez3_0007.zkey
withdraw_hez3_final.zkey [beaconHash] 10

After this, we will generate the 3 solidity verification contracts this way:

snarkjs zkey export solidityverifier circuit_1912_32_256_60_hez3_final.zkey verifier1912.sol
snarkjs zkey export solidityverifier circuit_344_32_256_60_hez3_final.zkey verifier344.sol
snarkjs zkey export solidityverifier withdraw_hez3_final.zkey verifier_withdraw.sol

In order to guarantee that this procedure is verificable later on, we published on-chain the details of this procedure here:

You can see that the timestamp of the transaction with the procedure precedes the random number generation.

What’s Next

We recently restarted the testnet after the Poseidon fix. After some more intensive testing days with the community, we will launch the Hermez Network mainnet.

These are fascinating times for everyone involved in the project, and we’d like to invite you to try it for yourself. Your feedback will be much appreciated!

You can contribute by testing the public testnet and giving your feedback on Discord. We will be sharing updates related to the mainnet launch on Twitter and Telegram.

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