ZoKrates

https://zokrates.github.io/
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ZoKrates is a toolbox for zkSNARKs on Ethereum that enables developers to create verifiable...
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### Full ZoKrates Workflow Example

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Demonstrates the complete ZoKrates workflow: compilation, witness computation, trusted setup, proof generation, and verification using the JavaScript bindings.

```javascript
initialize().then((zokratesProvider) => {
  const source = "def main(private field a) -> field { return a * a; }";

  // compilation
  const artifacts = zokratesProvider.compile(source);

  // computation
  const { witness, output } = zokratesProvider.computeWitness(artifacts, ["2"]);

  // run setup
  const keypair = zokratesProvider.setup(artifacts.program);

  // generate proof
  const proof = zokratesProvider.generateProof(
    artifacts.program,
    witness,
    keypair.pk
  );

  // export solidity verifier
  const verifier = zokratesProvider.exportSolidityVerifier(keypair.vk);

  // or verify off-chain
  const isVerified = zokratesProvider.verify(keypair.vk, proof);
});
```

--------------------------------

### Setup and Export Verifier

Source: https://zokrates.github.io/print.html

Performs the setup phase to generate keys and exports the verifier smart contract.

```bash
zokrates setup
zokrates export-verifier
```

--------------------------------

### View ZoKrates Subcommands

Source: https://zokrates.github.io/toolbox/cli.html

Run this command to see an overview of all available subcommands in the ZoKrates CLI. No setup is required beyond having ZoKrates installed.

```bash
zokrates
```

--------------------------------

### Perform Universal Trusted Setup for Marlin Scheme

Source: https://zokrates.github.io/print.html

Performs the universal phase of a trusted setup, specifically for the 'marlin' proving scheme. Requires specifying the size of the setup as an exponent.

```javascript
zokratesProvider.universalSetup(8);
```

--------------------------------

### Generate Trusted Setup with Universal Public Parameters (Marlin Scheme)

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Generates a trusted setup keypair using pre-computed universal public parameters from the universal setup phase for the Marlin scheme.

```javascript
const keypair = zokratesProvider.universalSetupKeypair(srs, artifacts.program);
```

--------------------------------

### Install ZoKrates JS

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Install the zokrates-js package using npm.

```bash
npm install zokrates-js
```

--------------------------------

### Perform Universal Setup Phase (Marlin Scheme)

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Performs the universal phase of a trusted setup, required for the Marlin proving scheme. Takes a size exponent and optional entropy.

```javascript
const srs = zokratesProvider.universalSetup(8);
```

--------------------------------

### Compile and Setup ZoKrates Program

Source: https://zokrates.github.io/print.html

Initializes the proving and verification keys for a ZoKrates program.

```bash
zokrates compile -i reveal_bit.zok -o reveal_bit
zokrates setup -i reveal_bit
```

--------------------------------

### ZoKrates.js Universal Setup (Marlin Scheme)

Source: https://zokrates.github.io/print.html

Perform the universal phase of a trusted setup, specifically for the Marlin proving scheme.

```APIDOC
## ZoKrates.js Universal Setup (Marlin Scheme)

### Description
Performs the universal phase of a trusted setup. This method is only available when using the `marlin` proving scheme.

### Method
`zokratesProvider.universalSetup(size: number): SetupKeypair`

### Endpoint
N/A (Client-side JavaScript library)

### Parameters
#### `size`
- **`size`** (number) - Required - The size of the trusted setup, passed as an exponent. For example, `8` for `2**8`.

### Returns
`SetupKeypair` - An object containing the proving key (`pk`) and verification key (`vk`).

### Request Example
```javascript
// This requires the scheme to be set to 'marlin' during initialization or via withOptions
const keypair = zokratesProvider.universalSetup(8); // For a setup size of 2**8
```
```

--------------------------------

### Compile and Setup Verification

Source: https://zokrates.github.io/examples/sha256example.html

Commands to compile the updated circuit and generate verification keys and smart contracts.

```bash
zokrates compile -i hashexample.zok
```

```bash
zokrates setup
zokrates export-verifier
```

```bash
zokrates compute-witness -a 0 0 0 5
```

--------------------------------

### ZoKrates Example Program

Source: https://zokrates.github.io/toolbox/abi.html

This is an example ZoKrates program that defines structs and a main function. It is used to illustrate ABI generation and argument passing.

```zokrates
struct Bar {
    field a;
}

struct Foo {
    u8 a;
    Bar b;
}

def main(Foo foo, bool[2] bar, field num) -> field {
    return 42;
}

```

--------------------------------

### ZoKrates.js Trusted Setup

Source: https://zokrates.github.io/print.html

Generate a trusted setup (keypair) for a compiled ZoKrates program.

```APIDOC
## ZoKrates.js Trusted Setup

### Description
Generates a trusted setup (keypair) required for generating zero-knowledge proofs. This involves a cryptographic ceremony.

### Method
`zokratesProvider.setup(program: string, entropy?: string): SetupKeypair`

### Endpoint
N/A (Client-side JavaScript library)

### Parameters
#### `program`
- **`program`** (string) - Required - The compiled program from `CompilationArtifacts`.

#### `entropy`
- **`entropy`** (string) - Optional - User-provided randomness to influence the setup.

### Returns
`SetupKeypair` - An object containing the proving key (`pk`) and verification key (`vk`).

### Request Example
```javascript
// Assuming 'artifacts' is the result of zokratesProvider.compile()
const keypair = zokratesProvider.setup(artifacts.program);
```
```

--------------------------------

### Install ZoKrates with cURL

Source: https://zokrates.github.io/gettingstarted.html

Installs ZoKrates using a one-line command for Linux, MacOS, and FreeBSD.

```bash
curl -LSfs get.zokrat.es | sh
```

--------------------------------

### ZoKrates CLI Workflow

Source: https://zokrates.github.io/gettingstarted.html

Demonstrates the typical workflow for using the ZoKrates CLI, including compilation, setup, witness computation, proof generation, and verification.

```bash
# compile
zokrates compile -i root.zok
# perform the setup phase
zokrates setup
# execute the program
zokrates compute-witness -a 337 113569
# generate a proof of computation
zokrates generate-proof
# export a solidity verifier
zokrates export-verifier
# or verify natively
zokrates verify
```

--------------------------------

### Compile a ZoKrates program

Source: https://zokrates.github.io/toolbox/trusted_setup.html

Compile the circuit file into a format ready for setup.

```bash
zokrates compile -i program.zok -o circuit
```

--------------------------------

### Generate Trusted Setup Keypair

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Generates a trusted setup keypair (proving and verification keys) for a compiled ZoKrates program. An optional entropy can be provided for randomness.

```javascript
const keypair = zokratesProvider.setup(artifacts.program);
```

--------------------------------

### ZoKrates Example Program for Nova

Source: https://zokrates.github.io/toolbox/experimental.html

A simple ZoKrates program demonstrating addition, suitable for use with the Nova proof system. It takes a public sum and a private element, returning their sum.

```zokrates
def main(public field sum, private field element) -> field {
    return sum + element;
}
```

--------------------------------

### Trusted Setup Generation

Source: https://zokrates.github.io/print.html

Generates a trusted setup with universal public parameters for the compiled program, specifically for the marlin scheme.

```APIDOC
## POST /setup/marlin

### Description
Generates a trusted setup with universal public parameters for the compiled program. Only available for the marlin scheme.

### Parameters
#### Request Body
- **srs** (object) - Required - Universal public parameters from the universal setup phase
- **program** (object) - Required - Compiled program

### Response
#### Success Response (200)
- **SetupKeypair** (object) - The generated setup keypair
```

--------------------------------

### Generate Zokrates Setup Keys

Source: https://zokrates.github.io/examples/rng_tutorial.html

Generates the proving and verification keys required for creating and verifying zero-knowledge proofs.

```bash
zokrates setup -i reveal_bit
```

--------------------------------

### Start Truffle Console

Source: https://zokrates.github.io/examples/rng_tutorial.html

Launches the Truffle interactive JavaScript console for contract deployment and interaction.

```bash
truffle console
```

--------------------------------

### Initialize MPC ceremony

Source: https://zokrates.github.io/toolbox/trusted_setup.html

Start the phase 2 ceremony using the compiled circuit and phase 1 parameters.

```bash
$ zokrates mpc init -i circuit -o mpc.params -r ./phase1radix2m2
```

--------------------------------

### Array Declaration and Initialization Syntax

Source: https://zokrates.github.io/language/types.html

Basic examples of declaring and initializing arrays with specific values or repeated constants.

```ZoKrates
field[3] a = [1, 2, 3]; // initialize a field array with field values
bool[13] b = [false; 13]; // initialize a bool array with value false
```

--------------------------------

### Simple Nova Program Example

Source: https://zokrates.github.io/print.html

A basic ZoKrates program demonstrating Nova's functionality, which adds a private element to a public sum.

```zokrates
__
def main(public field sum, private field element) -> field {
    return sum + element;
}


```

--------------------------------

### Get Help for ZoKrates Subcommand

Source: https://zokrates.github.io/toolbox/cli.html

Use the --help flag with any ZoKrates subcommand to get detailed usage information. This is useful for understanding specific command options and parameters.

```bash
zokrates compile --help
```

--------------------------------

### ZoKrates ABI Specification Example

Source: https://zokrates.github.io/toolbox/abi.html

This JSON object represents the ABI specification generated for the example ZoKrates program. It details the input and output types, names, and structures.

```json
{
   "inputs":[
      {
         "name":"foo",
         "public":true,
         "type":"struct",
         "components":{
            "name":"Foo",
            "members":[
               {
                  "name":"a",
                  "type":"u8"
               },
               {
                  "name":"b",
                  "type":"struct",
                  "components":{
                     "name":"Bar",
                     "members":[
                        {
                           "name":"a",
                           "type":"field"
                        }
                     ]
                  }
               }
            ]
         }
      },
      {
         "name":"bar",
         "public":true,
         "type":"array",
         "components":{
            "size":2,
            "type":"bool"
         }
      },
      {
         "name":"num",
         "public":true,
         "type":"field"
      }
   ],
   "output": {
     "type":"field"
   }
}

```

--------------------------------

### Witness Output Example

Source: https://zokrates.github.io/examples/rng_tutorial.html

The resulting witness output after computing the hash of the provided inputs.

```text
Computing witness...

Witness:

["3592665057","2164530888","1223339564","3041196771","2006723467","2963045520","3851824201","3453903005"]
```

--------------------------------

### ZoKrates Assembly: Quadratic Constraint Example

Source: https://zokrates.github.io/language/assembly.html

Demonstrates a valid quadratic constraint 'x * (x - 1) === 0;' which ZoKrates may transform.

```zokrates
asm {
    x * (x - 1) === 0;
}
```

--------------------------------

### Constraint transformation example

Source: https://zokrates.github.io/print.html

ZoKrates may transform constraints to meet the required quadratic format.

```ZoKrates
asm {
    x * (x - 1) === 0;
}
```

```ZoKrates
asm {
    x === x * x;
}
```

--------------------------------

### Generic Functions

Source: https://zokrates.github.io/print.html

Examples of generic functions over u32 values, including explicit parameter passing.

```ZoKrates
def foo<N>() -> field[N] {
    return [42; N];
}

def main() -> field[2] {
    field[2] res = foo();
    return res;
}
```

```ZoKrates
// a function to sum the N first powers of a field element
def sum_powers<N>(field a) -> field {
    field mut res = 0;
    for u32 i in 0..N {
        res = res + a ** i;
    }
    return res;
}

def main(field a) -> field {
    // call `sum_powers` providing the explicit generic parameter `N := 5`
    return sum_powers::<5>(a);
}
```

--------------------------------

### Tuple Usage in ZoKrates

Source: https://zokrates.github.io/print.html

Provides an example of using tuples in ZoKrates to group different data types. Shows how to declare, initialize, and modify tuple elements using dot notation.

```zokrates
__
def main() -> bool {
    (field[2], bool) mut v = ([1, 2], true);
    v.0 = [42, 43];
    return v.1;
}

```

--------------------------------

### Invalid non-quadratic constraint example

Source: https://zokrates.github.io/print.html

Constraints must be quadratic; expressions like d === a*b*c are disallowed.

```ZoKrates
asm {
    d === a*b*c;
}
```

--------------------------------

### File System Resolver for ZoKrates Imports

Source: https://zokrates.github.io/toolbox/zokrates_js.html

A Node.js example of a file system resolver function that can be used with ZoKrates compilation to resolve imported modules.

```javascript
import fs from "fs";
import path from "path";

const fileSystemResolver = (from, to) => {
  const location = path.resolve(path.dirname(path.resolve(from)), to);
  const source = fs.readFileSync(location).toString();
  return { source, location };
};
```

--------------------------------

### Initialize and Prove Nova Iterations

Source: https://zokrates.github.io/print.html

Set up initial state and step inputs, then generate a proof for multiple iterations using ZoKrates Nova.

```bash
__
echo "\"0\"" > init.json
echo "[\"1\", \"7\", \"42\"]" > steps.json
zokrates nova prove

```

--------------------------------

### Importing from Parent Directories

Source: https://zokrates.github.io/print.html

Demonstrates how to import resources from parent directories using relative paths like `../`.

```zokrates
__
from "../../../mycode" import foo;

```

--------------------------------

### Access ZoKrates CLI help

Source: https://zokrates.github.io/print.html

Run the base command or use --help to view available subcommands.

```bash
zokrates
```

```bash
zokrates compile --help
```

--------------------------------

### Importing from Local Directory

Source: https://zokrates.github.io/print.html

Shows how to import a resource directly from a file in the same directory.

```zokrates
__
from "./mycode" import foo;

```

--------------------------------

### Inner Bit Loop

Source: https://zokrates.github.io/print.html

Starts the loop to iterate through the 32 bits of a word.

```ZoKrates
        for u32 bit in 0..32 {
```

--------------------------------

### Comment for Bit Conversion

Source: https://zokrates.github.io/print.html

Placeholder comment indicating the start of bit conversion logic.

```ZoKrates
    // Convert the preimage to bits
```

--------------------------------

### Initialize ZoKrates Provider with Options

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Initializes the ZoKrates provider with custom options for backend, curve, and proving scheme. Returns a `ZoKratesProvider` configured with given options.

```javascript
initialize().then((defaultProvider) => {
  let zokratesProvider = defaultProvider.withOptions({
    backend: "ark",
    curve: "bls12_381",
    scheme: "g16",
  });
  // ...
});
```

--------------------------------

### Build ZoKrates from Source

Source: https://zokrates.github.io/gettingstarted.html

Builds ZoKrates from its GitHub repository. Ensure to set the ZOKRATES_STDLIB environment variable.

```bash
git clone https://github.com/ZoKrates/ZoKrates
cd ZoKrates
export ZOKRATES_STDLIB=$PWD/zokrates_stdlib/stdlib
cargo build -p zokrates_cli --release
cd target/release
```

--------------------------------

### Verify ZoKrates Proof

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Verifies a generated ZK-SNARK proof using the verification key obtained from the trusted setup.

```javascript
const isVerified = zokratesProvider.verify(keypair.vk, proof);
```

--------------------------------

### Import Bit Conversion Utility

Source: https://zokrates.github.io/examples/rng_tutorial.html

Import the utility to convert u32 values to boolean arrays.

```zok
import "utils/casts/u32_to_bits" as u32_to_bits;
```

--------------------------------

### Run ZoKrates with Docker

Source: https://zokrates.github.io/gettingstarted.html

Launches an interactive ZoKrates Docker container.

```bash
docker run -ti zokrates/zokrates /bin/bash
```

--------------------------------

### Return Multiple Values

Source: https://zokrates.github.io/examples/rng_tutorial.html

Zokrates functions can return multiple values by separating them with commas. This example returns a hash and a specific bit.

```zokrates
return (sha256(preimage[0..8], preimage[8..16]), preimageBits[bitNum]);
```

--------------------------------

### Initialize ZoKrates JS (Browser Script)

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Include the ZoKrates JS library via a script tag for browser usage and initialize it.

```html
<script src="https://unpkg.com/zokrates-js@latest/umd.min.js"></script>
<script>
  zokrates.initialize().then((zokratesProvider) => {
    /* ... */
  });
</script>
```

--------------------------------

### Generate and Verify Proofs with ZoKrates CLI

Source: https://zokrates.github.io/print.html

Commands to compute a witness, generate a proof, and verify it using the bellman backend.

```bash
zokrates compute-witness -i circuit -a 123456789 987654321 --verbose
zokrates generate-proof -i circuit -b bellman
zokrates verify -b bellman
```

--------------------------------

### Define a ZoKrates program

Source: https://zokrates.github.io/toolbox/trusted_setup.html

Create a basic circuit file named program.zok.

```zokrates
def main(private field a, private field b) -> field {
    return a * b;
}
```

--------------------------------

### Create Tampered Proof Input

Source: https://zokrates.github.io/examples/rng_tutorial.html

Creates a modified version of the proof inputs to simulate a cheating attempt. This example flips the last bit of the last input.

```javascript
cheat = [...proof.inputs]
cheat[cheat.length-1] = cheat[cheat.length-1].replace(/[01]$/, cheat[cheat.length-1][65] == '1' ? '0': '1')
```

--------------------------------

### Generate and Verify Proofs with Zokrates

Source: https://zokrates.github.io/toolbox/trusted_setup.html

Use the exported keys to generate proofs and verify them. This involves computing witness, generating the proof, and then verifying it.

```bash
# use the keys to generate proofs and verify
zokrates compute-witness -i circuit -a 123456789 987654321 --verbose
zokrates generate-proof -i circuit -b bellman
zokrates verify -b bellman
```

--------------------------------

### Large Field Element Representation in ZIR

Source: https://zokrates.github.io/print.html

ZoKrates uses an isomorphism to display large field elements in ZIR. This example shows how 'p - 1' is represented as '-1'.

```plaintext
-1
```

--------------------------------

### Initialize ZoKrates JS (Dynamic Import)

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Dynamically import the initialize function from zokrates-js.

```javascript
let { initialize } = await import("zokrates-js");
```

--------------------------------

### ZoKrates.js Initialization

Source: https://zokrates.github.io/print.html

Initialize the ZoKrates.js provider. This is the first step before using any other ZoKrates.js functionalities.

```APIDOC
## ZoKrates.js Initialization

### Description
Initializes the ZoKrates.js provider. This function returns a promise that resolves to a `ZoKratesProvider` instance.

### Method
`initialize()`

### Endpoint
N/A (Client-side JavaScript library)

### Returns
`Promise<ZoKratesProvider>` - A promise that resolves to an initialized `ZoKratesProvider`.

### Request Example
```javascript
import { initialize } from "zokrates-js";

initialize().then((zokratesProvider) => {
  // Use zokratesProvider here
});
```

### Response Example
```javascript
// The resolved value is a ZoKratesProvider instance
```
```

--------------------------------

### Compute Witness and Generate Proof

Source: https://zokrates.github.io/examples/rng_tutorial.html

Computes the witness file with program parameters and then generates the zero-knowledge proof using the witness and proving key.

```bash
zokrates compute-witness --verbose -i reveal_bit -a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 510
zokrates generate-proof -i reveal_bit
```

--------------------------------

### Constant Definitions

Source: https://zokrates.github.io/print.html

Shows how to define global constants and reference them within functions.

```ZoKrates
const field PRIME = 31;

def main() -> field {
    return PRIME;
}
```

```ZoKrates
const field ONE = 1;
const field TWO = ONE + ONE;

def main() -> field {
    return TWO;
}
```

--------------------------------

### Compile a ZoKrates program

Source: https://zokrates.github.io/print.html

Define a main function and compile it into a circuit file.

```ZoKrates
def main(private field a, private field b) -> field {
    return a * b;
}
```

```bash
zokrates compile -i program.zok -o circuit
```

--------------------------------

### Array Initialization and Manipulation

Source: https://zokrates.github.io/language/types.html

Shows various ways to initialize, modify, and slice arrays in ZoKrates.

```ZoKrates
def main() -> field {
    field[3] mut a = [1, 2, 3]; // initialize a field array with field values
    a[2] = 4;               // set a member to a value
    field[4] b = [42; 4];   // initialize an array of 4 values all equal to 42
    field[4] c = [...a, 4]; // initialize an array copying values from `a`, followed by 4
    field[2] d = a[1..3];   // initialize an array copying a slice from `a`
    bool[3] e = [true, true || false, true]; // initialize a boolean array
    u32 SIZE = 3;
    field[SIZE] f = [1, 2, 3]; // initialize a field array with a size that's a compile-time constant
    return a[0] + b[1] + c[2];
}
```

--------------------------------

### Initialize and contribute to MPC ceremony

Source: https://zokrates.github.io/print.html

Commands for initializing a phase 2 ceremony and contributing to the parameters.

```bash
$ zokrates mpc init -i circuit -o mpc.params -r ./phase1radix2m2

Initializing MPC...
Parameters written to `mpc.params`
```

```bash
$ zokrates mpc contribute -i mpc.params -o alice.params -e "alice 1"

Contributing to `mpc.params`...
The BLAKE2b hash of your contribution is:

        4ebf1359 416fbc42 31af6476 9173cb33 
        32b8c2f9 475d143a 25634a5c e461eb67
```

--------------------------------

### Array Initialization and Usage in ZoKrates

Source: https://zokrates.github.io/print.html

Shows various ways to declare and initialize static arrays in ZoKrates, including arrays of fields, booleans, and arrays with compile-time constant sizes. Demonstrates element assignment, initialization with repeated values, and array composition using the spread operator.

```zokrates
__
def main() -> field {
    field[3] mut a = [1, 2, 3]; // initialize a field array with field values
    a[2] = 4;               // set a member to a value
    field[4] b = [42; 4];   // initialize an array of 4 values all equal to 42
    field[4] c = [...a, 4]; // initialize an array copying values from `a`, followed by 4
    field[2] d = a[1..3];   // initialize an array copying a slice from `a`
    bool[3] e = [true, true || false, true]; // initialize a boolean array
    u32 SIZE = 3;
    field[SIZE] f = [1, 2, 3]; // initialize a field array with a size that's a compile-time constant
    return a[0] + b[1] + c[2];
}

```

--------------------------------

### Generate Proof with ZoKrates

Source: https://zokrates.github.io/examples/sha256example.html

Run this command to construct the zkSNARK proof. Inputs declared as private in the program will not appear in the proof.

```bash
zokrates generate-proof
```

--------------------------------

### Verify Nova Proof

Source: https://zokrates.github.io/print.html

Verify the compressed Nova proof.

```bash
__
zokrates nova verify

```

--------------------------------

### Initialize ZoKrates Provider

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Initializes the ZoKrates provider. Returns an initialized `ZoKratesProvider` as a promise.

```javascript
initialize().then((zokratesProvider) => {
  // call api functions here
});
```

--------------------------------

### Continue Nova Proof with More Steps

Source: https://zokrates.github.io/print.html

Extend an existing Nova proof by adding more computation steps with new intermediate inputs.

```bash
__
zokrates nova prove --continue

```

--------------------------------

### Compile and Run Reveal Bit Program

Source: https://zokrates.github.io/examples/rng_tutorial.html

Commands to compile the reveal bit circuit and compute a witness with a specific bit index.

```bash
zokrates compile -i reveal_bit.zok -o reveal_bit
zokrates compute-witness --verbose -i reveal_bit -a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 510
```

--------------------------------

### Verify Proof with Web3

Source: https://zokrates.github.io/toolbox/verification.html

Use web3.js to interact with a verifier smart contract and check a proof. Ensure the verifier contract address and ABI are correctly set.

```javascript
const accounts = await web3.eth.getAccounts();
const address = '0x456...'; // verifier contract address

let verifier = new web3.eth.Contract(abi, address, {
    from: accounts[0], // default from address
    gasPrice: '20000000000000'; // default gas price in wei
});

let result = await verifier.methods
    .verifyTx(proof.proof, proof.inputs)
    .call({ from: accounts[0] });

```

--------------------------------

### Initialize ZoKrates JS (ES Module)

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Import the initialize function from the zokrates-js library when using ES modules.

```javascript
import { initialize } from "zokrates-js";
```

--------------------------------

### Check Solidity Version

Source: https://zokrates.github.io/examples/rng_tutorial.html

Searches for the Solidity version pragma directive within the 'verifier.sol' file.

```bash
grep solidity contracts/verifier.sol
```

--------------------------------

### Compile and Inspect ZoKrates Program

Source: https://zokrates.github.io/examples/rng_tutorial.html

Commands to compile the ZoKrates source file and generate a textual representation of the circuit.

```bash
zokrates compile -i get_hash.zok -o get_hash && zokrates inspect -i get_hash
```

--------------------------------

### ZoKrates Nova Prove Command

Source: https://zokrates.github.io/toolbox/experimental.html

Generate a Nova proof for a compiled ZoKrates program. Initial state and step inputs are provided via JSON files. The proof is saved to proof.json.

```bash
echo "\"0\"" > init.json
echo "[\"1\", \"7\", \"42\"]" > steps.json
zokrates nova prove
```

--------------------------------

### ZoKrates Nova Continue Prove Command

Source: https://zokrates.github.io/toolbox/experimental.html

Extend an existing Nova proof by running additional steps. This is useful for iterative computations where the state can be carried over.

```bash
zokrates nova prove --continue
```

--------------------------------

### Initialize Bit Array

Source: https://zokrates.github.io/print.html

Initializes a mutable array of 512 boolean values to false.

```ZoKrates
    bool[512] mut preimageBits = [false; 512];
    for u32 i in 0..16 {
```

--------------------------------

### Verify MPC Ceremony Contributions

Source: https://zokrates.github.io/toolbox/trusted_setup.html

Run this command to verify contributions to the MPC ceremony. Ensure you have the final parameters and circuit files.

```bash
$ zokrates mpc verify -i final.params -c circuit -r ./phase1radix2m2
```

--------------------------------

### ZoKratesProvider Configuration

Source: https://zokrates.github.io/print.html

Configure the ZoKratesProvider with specific backend, curve, and proving scheme options.

```APIDOC
## ZoKratesProvider Configuration

### Description
Configures the `ZoKratesProvider` with custom options for the backend, elliptic curve, and proving scheme. This method returns a new `ZoKratesProvider` instance with the specified configuration.

### Method
`zokratesProvider.withOptions(options: ZoKratesOptions): ZoKratesProvider`

### Endpoint
N/A (Client-side JavaScript library)

### Parameters
#### Options
- **`backend`** (string) - Optional - Backend to use. Options: `ark` | `bellman`. Default: `ark`.
- **`curve`** (string) - Optional - Elliptic curve to use. Options: `bn128` | `bls12_381` | `bls12_377` | `bw6_761`. Default: `bn128`.
- **`scheme`** (string) - Optional - Proving scheme to use. Options: `g16` | `gm17` | `marlin`. Default: `g16`.

### Request Example
```javascript
initialize().then((defaultProvider) => {
  let zokratesProvider = defaultProvider.withOptions({
    backend: "ark",
    curve: "bls12_381",
    scheme: "g16",
  });
  // Use the configured zokratesProvider
});
```

### Returns
`ZoKratesProvider` - A new `ZoKratesProvider` instance configured with the provided options.
```

--------------------------------

### Define and Use Nested Structs

Source: https://zokrates.github.io/language/types.html

Demonstrates defining generic structs and initializing them within a main function.

```ZoKrates
struct Bar<N> {
    field[N] c;
    bool d;
}

struct Foo<P> {
    Bar<P> a;
    bool b;
}

def main() -> Foo<2> {
    Foo<2>[2] mut f = [Foo { a: Bar { c: [0, 0], d: false }, b: true}, Foo { a: Bar {c: [0, 0], d: false}, b: true }];
    f[0].a.c = [42, 43];
    return f[0];
}
```

--------------------------------

### Define Type Aliases

Source: https://zokrates.github.io/language/types.html

Shows how to create type aliases for existing types and generic types.

```ZoKrates
type MyField = field;

type Rectangle<L, W> = bool[L][W];

type Square<S> = Rectangle<S, S>;

def main() {
    MyField f = 42;
    Rectangle<2, 2> r = [[true; 2]; 2];
    Square<2> s = r;
    return;
}
```

--------------------------------

### ZoKrates Nova Compile Command

Source: https://zokrates.github.io/toolbox/experimental.html

Compile a ZoKrates program for the Nova proof system using the Pallas curve. Ensure the program signature matches the required format for Nova.

```bash
zokrates compile -i sum.zok --curve pallas
```

--------------------------------

### Compile and Inspect ZoKrates Program

Source: https://zokrates.github.io/print.html

Compile a ZoKrates program and inspect its intermediate representation.

```bash
__
zokrates compile -i get_hash.zok -o get_hash && zokrates inspect -i get_hash

```

--------------------------------

### Initialize a Struct Variable

Source: https://zokrates.github.io/language/types.html

Demonstrates declaring and initializing a struct variable in a single statement.

```ZoKrates
struct Point {
    field x;
    field y;
}

def main() -> Point {
    Point p = Point { x: 1, y: 0 };
    return p;
}
```

--------------------------------

### Compile Solidity Contract with Truffle

Source: https://zokrates.github.io/examples/rng_tutorial.html

Compiles the smart contracts in the Truffle project, including the exported 'verifier.sol'.

```bash
truffle compile
```

--------------------------------

### Proof Formatting

Source: https://zokrates.github.io/print.html

Formats the proof into an array of field elements compatible with the generated Solidity contract.

```APIDOC
## POST /proof/format

### Description
Formats the proof into an array of field elements that are compatible as input to the generated solidity contract.

### Parameters
#### Request Body
- **proof** (object) - Required - Generated proof

### Response
#### Success Response (200)
- **elements** (array) - Array of field elements
```

--------------------------------

### Compile ZoKrates Program

Source: https://zokrates.github.io/print.html

Compiles the specified ZoKrates file into an arithmetic circuit.

```bash
zokrates compile -i hashexample.zok
```

--------------------------------

### Import SHA256 Library

Source: https://zokrates.github.io/examples/rng_tutorial.html

Import the SHA256 function from the ZoKrates standard library.

```zok
import "hashes/sha256/512bit" as sha256;
```

--------------------------------

### Compile and Compute Witness

Source: https://zokrates.github.io/examples/sha256example.html

Commands to compile the circuit and generate a witness for specific input values.

```bash
zokrates compile -i hashexample.zok
```

```bash
zokrates compute-witness -a 0 0 0 5 --verbose
```

--------------------------------

### Relative path imports

Source: https://zokrates.github.io/language/imports.html

Import resources using relative paths within the file system.

```ZoKrates
from "./mycode" import foo;
```

```ZoKrates
from "../../../mycode" import foo;
```

--------------------------------

### Compute Witness for Hash Program

Source: https://zokrates.github.io/examples/rng_tutorial.html

Execute the compiled circuit with specific input arguments to generate a witness.

```bash
zokrates compute-witness --verbose -i get_hash -a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
```

--------------------------------

### Tuple Usage

Source: https://zokrates.github.io/language/types.html

Demonstrates defining and accessing elements within a tuple.

```ZoKrates
def main() -> bool {
    (field[2], bool) mut v = ([1, 2], true);
    v.0 = [42, 43];
    return v.1;
}
```

--------------------------------

### Verify Zokrates Proof

Source: https://zokrates.github.io/examples/rng_tutorial.html

Verifies the generated zero-knowledge proof. This command assumes 'proof.json' is in the current directory.

```bash
zokrates verify
```

--------------------------------

### Unsigned Integer Arithmetic and Inference

Source: https://zokrates.github.io/language/types.html

Demonstrates how decimal literals are inferred based on context and how unsigned integer arithmetic handles overflows.

```ZoKrates
def main() {
    // `255` is inferred to `255f`, and the addition happens between field elements
    assert(255 + 1f == 256);

    // `255` is inferred to `255u8`, and the addition happens between u8
    // This causes an overflow
    assert(255 + 1u8 == 0);

    return;
}
```

--------------------------------

### Define Main Function Signature

Source: https://zokrates.github.io/examples/rng_tutorial.html

The entry point for the ZoKrates program accepting 16 unsigned 32-bit integers.

```zok
def main(u32[16] hashMe) -> u32[8] {
```

--------------------------------

### Alice's Contribution to MPC Ceremony

Source: https://zokrates.github.io/print.html

Alice initiates the MPC ceremony by providing her contribution, which includes entropy. This step generates the initial `alice.params` file.

```bash
__
$ zokrates mpc contribute -o alice.params -e "alice 1"
```

--------------------------------

### ZoKrates Program Execution Arguments

Source: https://zokrates.github.io/toolbox/abi.html

This JSON array shows how to format arguments for executing a ZoKrates program based on its ABI specification. Note the specific formatting for field elements, unsigned integers, and structs.

```json
[
   {
      "a":"0x2a",
      "b":{
         "a":"42"
      }
   },
   [
      true,
      false
   ],
   "42"
]

```

--------------------------------

### ZoKrates Array Slicing

Source: https://zokrates.github.io/print.html

Demonstrates array slicing in ZoKrates, where a subset of an existing array is copied to create a new array.

```zokrates
__
field[3] a = [1, 2, 3];
field[2] b = a[1..3];   // initialize an array copying a slice from `a`

```

--------------------------------

### Call Generic Function with Explicit Parameters

Source: https://zokrates.github.io/language/functions.html

Demonstrates calling a generic function, `sum_powers`, by explicitly providing the generic parameter `N` using the `::<N>` syntax.

```zokrates
// a function to sum the N first powers of a field element
def sum_powers<N>(field a) -> field {
    field mut res = 0;
    for u32 i in 0..N {
        res = res + a ** i;
    }
    return res;
}

def main(field a) -> field {
    // call `sum_powers` providing the explicit generic parameter `N := 5`
    return sum_powers::<5>(a);
}
```

--------------------------------

### Initialize Preimage Bits Array

Source: https://zokrates.github.io/examples/rng_tutorial.html

Initializes a boolean array of 512 elements to false. Zokrates requires variables to be initialized upon declaration.

```zokrates
bool[512] mut preimageBits = [false; 512];
```

--------------------------------

### Format Proof for Solidity

Source: https://zokrates.github.io/toolbox/zokrates_js.html

Formats a generated proof into an array of field elements compatible with the generated Solidity contract.

```APIDOC
## POST /format-proof

### Description
Formats the proof into an array of field elements that are compatible as input to the generated solidity contract.

### Parameters
#### Request Body
- **proof** (object) - Required - Generated proof

### Response
#### Success Response (200)
- **result** (array) - Returns an array of field elements.
```

--------------------------------

### Verify a Zokrates proof using a smart contract

Source: https://zokrates.github.io/examples/rng_tutorial.html

Use this snippet to verify a proof against a deployed verifier contract. Ensure the proof parameters match the expected structure of the contract's verifyTx function.

```javascript
await contract.verifyTx(proof.proof.a, proof.proof.b, proof.proof.c, cheat)
```

--------------------------------

### Field Element Arithmetic in ZoKrates

Source: https://zokrates.github.io/language/types.html

Demonstrates arithmetic with field elements, specifically showing that 0 - 1 equals p - 1 in a finite field, where p is the large prime modulus. This highlights the modular arithmetic behavior.

```zokrates
def main() {
    field pMinusOne = 21888242871839275222246405745257275088548364400416034343698204186575808495616;
    assert(0 - 1 == pMinusOne);
    return;
}
```

--------------------------------

### Use generic parameters

Source: https://zokrates.github.io/language/control_flow.html

Generic parameters must be compile-time constants and can be inferred or provided explicitly.

```ZoKrates
def foo<N, P>() -> field[P] {
    return [42; P];
}

def main() -> field[2] {
    // `P` is inferred from the declaration of `res`, while `N` is provided explicitly
    field[2] res = foo::<3, _>();
    return res;
}
```

--------------------------------

### Multi-dimensional Array Declaration in ZoKrates

Source: https://zokrates.github.io/print.html

Demonstrates the syntax for declaring and accessing elements in multi-dimensional arrays (arrays of arrays) in ZoKrates. Shows how to initialize nested arrays and retrieve specific elements.

```zokrates
__
def main() -> field {
    // Array of two elements of array of 3 elements
    field[2][3] a = [[1, 2, 3],[4, 5, 6]];

    field[3] b = a[0]; // should be [1, 2, 3]

    // allowed access [0..2][0..3]
    return a[1][2];
}

```

--------------------------------

### Compute Witness

Source: https://zokrates.github.io/print.html

Generates a witness file using the provided arguments for the program inputs.

```bash
zokrates compute-witness -a 0 0 0 5 --verbose
```

```bash
zokrates compute-witness -a 0 0 0 5
```

--------------------------------

### Import multiple symbols

Source: https://zokrates.github.io/language/imports.html

Import multiple symbols from the same module by separating them with commas.

```ZoKrates
from "./path/to/my/module" import MySymbol, MyOtherSymbol;
```

--------------------------------

### Compile Zokrates Program

Source: https://zokrates.github.io/examples/rng_tutorial.html

Compiles the Zokrates program 'reveal_bit.zok' and outputs the compiled artifact to 'reveal_bit'.

```bash
zokrates compile -i reveal_bit.zok -o reveal_bit
```

--------------------------------

### Importing Symbols by Module and Name

Source: https://zokrates.github.io/print.html

Shows the preferred method for importing symbols from other ZoKrates modules using the `from ... import ...` syntax. This allows specific symbols to be brought into the current scope.

```zokrates
__
from "./path/to/my/module" import MySymbol;

// `MySymbol` is now in scope.

```

--------------------------------

### Import a single symbol

Source: https://zokrates.github.io/language/imports.html

Use the from keyword to import a specific symbol from a module path.

```ZoKrates
from "./path/to/my/module" import MySymbol;

// `MySymbol` is now in scope.
```
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