Circom Example

Prerequisites

1. Update submodules.

   git submodule update --init

2. Install prerequisite for Tachyon by following the instructions.

3. Install snarkjs.

   npm install -g snarkjs@latest

4. Prepare .bazelrc.user.

   • On Linux

     echo "build --config linux" > .bazelrc.user
     echo "build --@kroma_network_tachyon//:has_openmp" >> .bazelrc.user
     echo "build -c opt" >> .bazelrc.user

   • On Macos ARM64(After M1)

     echo "build --config macos_arm64" > .bazelrc.user
     echo "build -c opt" >> .bazelrc.user

   • On Macos x86(Before M1)

     echo "build --config macos_x86_64" > .bazelrc.user
     echo "build -c opt" >> .bazelrc.user

5. Sync the rust dependencies.

   CARGO_BAZEL_REPIN=1 bazel sync --only=crate_index

Circuit Descriptions

• adder.circom: It checks the addition of the two 32-bit unsigned integers. This circuit depends on circomlib library.
• multiplier_2_main.circom: It checks the multiplication of the two prime fields. This circuit is the first use case that uses circom_library.
• multiplier_3.circom: It checks the multiplication of the three prime fields. This circuit depends on multiplier_2.circom.
• sha256_512.circom: It checks the sha256 hash of the two 256-bit bytes. This circuit depends on circomlib library.

How to run

bazel run //src/{circuit_dir}:prover_main

{circuit_dir} should be one of these: adder, multiplier_2, multiplier_3 or sha256_512.

How to compile circom

This task is automatically called when running //src/{circuit_dir}:prover_main, but you can also compile a circuit manually like this example below.

bazel build //circuits/multiplier_2:compile_multiplier_2_main

As a result, these 3 files are generated.

• bazel-bin/circuits/multiplier_2/multiplier_2_main.r1cs
• bazel-bin/circuits/multiplier_2/multiplier_2_main_cpp/multiplier_2_main.cpp
• bazel-bin/circuits/multiplier_2/multiplier_2_main_cpp/multiplier_2_main.dat