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Installing the circom ecosystem

⚠ Important deprecation note

The old circom compiler written in Javascript will be frozen, but it can still be downloaded from the old circom repository.

Installing dependencies

You need several dependencies in your system to run circom and its associated tools.

  • The core tool is the circom compiler which is written in Rust. To have Rust available in your system, you can install rustup. If you’re using Linux or macOS, open a terminal and enter the following command:
curl --proto '=https' --tlsv1.2 https://sh.rustup.rs -sSf | sh
  • We also distribute a series of npm packages so Node.js and some package manager like npm or yarn should be available in your system. Recent versions of Node.js include big integer support and web assembly compilers that help run code faster, so to get a better performance, install version 10 or higher.

Installing circom

To install from our sources, clone the circom repository: 

git clone https://github.com/iden3/circom.git

Enter the circom directory and use the cargo build to compile:

cargo build --release

The installation takes around 3 minutes to be completed. When the command successfully finishes, it generates the circom binary in the directory target/release. You can install this binary as follows (Note: Make sure you're still in the circom directory when running this command) :

cargo install --path circom

The previous command will install the circom binary in the directory $HOME/.cargo/bin.

Now, you should be able to see all the options of the executable by using the help flag:

circom --help USAGE: circom [FLAGS] [OPTIONS] [--] [input] FLAGS: --r1cs Outputs the constraints in r1cs format --sym Outputs witness in sym format --wasm Compiles the circuit to wasm --json Outputs the constraints in json format --wat Compiles the circuit to wat -c, --c Compiles the circuit to C++ --O0 No simplification is applied --O1 Only applies signal to signal and signal to constant simplification. This is the default option --O2 Full constraint simplification --verbose Shows logs during compilation --inspect Does an additional check over the constraints produced --use_old_simplification_heuristics Applies the old version of the heuristics when performing linear simplification --simplification_substitution Outputs the substitution applied in the simplification phase in json format --no_asm Does not use asm files in witness generation code in C++ --no_init Removes initializations to 0 of variables ("var") in the witness generation code -h, --help Prints help information -V, --version Prints version information OPTIONS: -o, --output <output> Path to the directory where the output will be written [default: .] -p, --prime <prime> To choose the prime number to use to generate the circuit. Receives the name of the curve (bn128, bls12377, bls12381, goldilocks, grumpkin, pallas, secq256r1, vesta) [default: bn128] -l <link_libraries>... Adds directory to library search path --O2round <simplification_rounds> Maximum number of rounds of the simplification process --sanity_check <sanity_check> Selects the level of sanity checks to be included in the witness generation code generated. It receives the value 0, 1, or 2. [default: 2] ARGS: <input> Path to a circuit with a main component [default: ./circuit.circom]

Installing snarkjs

snarkjs is a npm package that contains code to generate and validate ZK proofs from the artifacts produced by circom.

You can install snarkjs with the following command:

npm install -g snarkjs