VocdoniZ Circom circuits

This repository includes the templates that compose the zk-snark circuit that allows to prove a valid vote, including the format of the vote itself and its encryption:

• Ballot checker (ballot_checker.circom): Checks that the ballot is valid under the params provided as inputs.

  template instances: 17
  non-linear constraints: 6409
  linear constraints: 0
  public inputs: 0
  private inputs: 14
  public outputs: 5
  wires: 6384
  labels: 7298
  

• Ballot cipher (ballot_cipher.circom): Encrypts the ballot fields using ElGamal and checks if they match with the provided ones.

  template instances: 26
  non-linear constraints: 3202
  linear constraints: 0
  public inputs: 8
  private inputs: 0
  public outputs: 0
  wires: 3207
  labels: 19411
  

• Ballot proof (ballot_proof.circom): Checks the ballot and its encryption, and calculates the nullifier with the inputs provided proving that it matches with the provided one.

  template instances: 111
  non-linear constraints: 35795
  linear constraints: 0
  public inputs: 42
  private inputs: 13
  public outputs: 0
  wires: 35744
  labels: 167345
  

  For n_fields = 8.
• Ballot proof hashed inputs (MiMC7) (ballot_proof_mimc.circom): Same as ballot_proof.circom, but in this case each input is private unless the hash (MiMC7) of each input is provided. This circuit also proves that the given hash is correct.

  template instances: 113
  non-linear constraints: 52175
  linear constraints: 0
  public inputs: 1
  private inputs: 55
  public outputs: 0
  wires: 55764
  labels: 187589
  

  For n_fields = 8.
• Ballot proof hashed inputs (Poseidon) (ballot_proof_poseidon.circom): Same as ballot_proof.circom, but in this case each input is private unless the hash (Poseidon) of each input is provided. This circuit also proves that the given hash is correct.

  template instances: 343
  non-linear constraints: 37817
  linear constraints: 0
  public inputs: 1
  private inputs: 55
  public outputs: 0
  wires: 38249
  labels: 181444
  

  For n_fields = 8.

Circuit compilation for testing

Requirements:

• Go
• Rust
• Node & NPM
• Snarkjs
• Circom

To test the circuits, first they should be compiled to generate the wasm, the proving and the verification key. The circuits can be compiled using prepare-circuit.sh script and the testing circuits under test/ folder:

• Ballot checker

  sh prepare-circuit.sh test/ballot_checker_test.circom

• Ballot cipher

  sh prepare-circuit.sh test/ballot_cipher_test.circom

• Ballot proof

  sh prepare-circuit.sh test/ballot_proof_test.circom

• Ballot proof hashed inputs (MiMC7)

  sh prepare-circuit.sh test/ballot_proof_mimc_test.circom

• Ballot proof hashed inputs (Poseidon)

  sh prepare-circuit.sh test/ballot_proof_poseidon_test.circom

Circuit testubg execution

The circuits execution (proof generation and verification) can be done using golang or typescript:

Go

• Ballot checker

  go test -timeout 30s -run ^TestBallotChecker$ github.com/vocdoni/z-ircuits/test -v -count=1

• Ballot cipher

  go test -timeout 30s -run ^TestBallotCipher$ github.com/vocdoni/z-ircuits/test -v -count=1

• Ballot proof

  go test -timeout 30s -run ^TestBallotProof$ github.com/vocdoni/z-ircuits/test -v -count=1

• Ballot proof hashed inputs (MiMC7)

  go test -timeout 30s -run ^TestBallotProofMiMC$ github.com/vocdoni/z-ircuits/test -v -count=1

• Ballot proof hashed inputs (Poseidon)

  go test -timeout 30s -run ^TestBallotProofPoseidon$ github.com/vocdoni/z-ircuits/test -v -count=1

Typescript

Setup

cd test/ts
npm i
npm run build

• Ballot checker

  npm run ballot_checker

• Ballot cipher

  npm run ballot_cipher

• Ballot proof

  npm run ballot_proof

• Ballot proof hashed inputs (Poseidon)

  npm run ballot_proof_poseidon