simple_mul

Multiplication Circuits

Preset

1. compile the circom code

   circom mul.circom --r1cs --wasm --sym

2. We are reuseing a phase 1 power of tau file and directly start phase 2.

   wget https://hermezptau.blob.core.windows.net/ptau/powersOfTau28_hez_final_12.ptau
   snarkjs powersoftau prepare phase2 powersOfTau28_hez_final_12.ptau pot12_final.ptau -v
   snarkjs groth16 setup mul.r1cs pot12_final.ptau mul_0000.zkey
   snarkjs zkey contribute mul_0000.zkey mul_0001.zkey --name="1st Contributor Name" -v
   snarkjs zkey export verificationkey mul_0001.zkey verification_key.json

Show the ciruit is faulty

1. Generate witness (now the mul.json has value {"x":"1", "y":"5"}.

   node mul_js/generate_witness.js mul_js/mul.wasm mul.json witness.wtns

2. Generate and verify proof.

   snarkjs groth16 prove mul_0001.zkey witness.wtns proof.json public.json
   snarkjs groth16 verify verification_key.json public.json proof.json

3. To demonstrate the circuit is faulty, change mul.json to {"x":"2", "y":"5"}.

   rm witness.wtns proof.json public.json
   node mul_js/generate_witness.js mul_js/mul.wasm mul.json witness.wtns
   snarkjs groth16 prove mul_0001.zkey witness.wtns proof.json public.json
   snarkjs groth16 verify verification_key.json public.json proof.json