# Zokrates

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Zokrates is a toolbox for zkSNARKs on Ethereum.

_This is a proof-of-concept implementation. It has not been tested for production._

# Motivation

Ethereum runs computations on all nodes of the network, resulting in high costs, limits in complexity, and low privacy.
SNARKs have been enabling to only verify computations on-chain for a fraction of the cost of running them, but are hard to grasp and work with.

Zokrates bridges this gap. It helps you create offchain programs and link them to the Ethereum blockchain, expanding the possibilities for your Dapp.

# Installation

Using Docker is currently the recommended way to get started with Zokrates.

```bash
docker run -ti kyroy/zokrates /bin/bash
```
Or build yourself with the following commands.
```bash
git clone https://github.com/JacobEberhardt/ZoKrates
cd ZoKrates
docker build -t zokrates .
docker run -ti zokrates /bin/bash
cd ZoKrates/target/release
```


# Example

To execute the program, perform the setup for the program, generate a proof
```
def add(a, b, c):
  return a + b + c
```
with `add(1, 2, 3)`, call
```
./zokrates compile -i 'add.code_path'
./zokrates compute-witness -a 1 2 3
./zokrates setup
./zokrates generate-proof
./zokrates export-verifier
```

# API reference

Zokrates provides a command line interface.
You can see an overview of the available subcommands by running

```
./zokrates
```

#### `compile`
```
./zokrates compile -i /path/to/add.code
```

Compile a `.code` file.

Creates a compiled `.code` file at `./out.code`.

#### `compute-witness`
```
./zokrates compute-witness -a 1 2
```

Computes a witness for the compiled program found at `./out.code` and arguments to the program.
A witness is a valid assignment of the variables, which include the results of the computation.

Creates a witness file at `./witness`

#### `setup`
```
./zokrates setup
```

Generates a trusted setup for the compiled program found at `./out.code`.

Creates a proving key and a verifying key at `./proving.key` and `./verifying.key`.

#### `export-verifier`
```
./zokrates export-verifier
```

Using the verifying key at `./verifying.key`, generates a Solidity contract enabling to verify proofs for computations of the compiled program at `./out.code`.

Creates a verifier contract at `./verifier.sol`

#### `generate-proof`
```
./zokrates generate-proof
```

Using the proving key at `./proving.key`, generates a proof for a computation of the compiled program `./out.code` resulting in `./witness`.

Returns the proof, for example:
```
A = 0x45582d7906c967b1fd1cac0aad3efefa526e4cd888b8ecb5907b46c2eb1f781, 0x8158089a63a6aafa4afc3bbfd5ebf392e5ef61d0c5faf2e2445c9112450f29c
A_p = 0x5e4fe0bfa79a571b8918138ee5d7b3d0ad394c9bb8f7d2e1549f7e3c3bab7e9, 0x1708b5ba3d138e433406c792f679ae6902fc9f7c6131305a9a5f826dbe2d71fb
B = [0x34f5c5b7518597452e55a69bf9171a63837a98a1c1c1870b610b2cfe79c4573, 0x18e56afd179d67960db838a8fdb128eb78d5dd2c1ffcd564f9d0dada928ed71f], [0xf160ea8d2dc33b564a45c0998309b4bf5a050cc8f6288793b7401b37d1eb1a2, 0x23ade8ba2c64300b5ff90e18641516407054a21179829252fd87f1bd61a3be34]
B_p = 0xc88b87d45f90da42b9c455da16dad76996ef5b1e859a4f0db7dcef4f7e3b2fd, 0x20ed7c62dd8c6c47506e6db1d4837daa42ae80b931227153054539dcbf6f3778
C = 0x2c230cbffbcb6211d2cf8f434df291a413721e3bef5ada4030d532d14b6ea504, 0x21421565f75429d0922c8cf00b68e4da23c61670e787ce6a5de14a5a86ebdcb0
C_p = 0xce11fe724ce1ce183c15c4f5405d9607d6c769422aa9f62f4868478324a2f5, 0x1e585b35ed22ef32fd70ef960818f1514d1dd94b3517c127e782de24173c69f9
H = 0x2306e74a1a7e318d2d3c40cbea708b0e0b91cd1548c9db6261fc2bd815740978, 0xde538e4e99b0e20e84cdbbd3bc08c37bca0af21edd67faf52bc4027a9b00f7c
K = 0x1868436121f271e9fbf78a8f75bb4077e2d4f208891793fd5b468afc3b05c0e4, 0x1021c3ecb15c3fd7340d4eb5bf446e1ad457020e4f8b7cc82f8af64507a35fbe
```

Passed to the verifier contract, this proof can be checked.

# Testing

Run normal tests with
```
cargo test
```
and run long and expensive tests with
```
cargo test -- --ignored
```