taco-integration

Integrating TACo into applications

{% hint style="warning" %} Note that using TACo in production requires a unique DKG initialization ritual, DKG public key and cohort of nodes running TACo software. These are available via a unique ritualID parameter. See the beta program page for instructions on how to initialize a DKG ritual. {% endhint %}

0. Pick an appropriate taco domain

Before we install taco, we need to consider which domain we would like to use:

• MAINNET (mainnet network) - production environment
• TESTNET (tapir network) - stable testnet that matches mainnet
• DEVNET (lynx network) - bleeding-edge testnet used for internal development and future features

{% hint style="info" %} tapir is the stable network recommended for developers. {% endhint %}

Once you've picked a network, install @nucypher/taco from npm.js with the appropriate tag based on the chosen network. To find the appropriate version, refer to the "Tags" column in the "Current Tags" section.

You can learn more about the current state of mainnet and test networks here:

• mainnet-taco-beta-program.md
• get-started-with-tac.md

1. Install and integrate taco

To begin, we need to install the taco , and taco-authlibraries:

yarn add @nucypher/taco @nucypher/taco-auth

For this guide, we'll need a few extra packages:

yarn add [email protected] @metamask/detect-provider

To use taco, we have to call initialize method first. This method takes care of initializing the WASM module for taco dependencies.

import { initialize } from '@nucypher/taco';

await initialize();

With this out of the way, we're ready to use taco in our app.

2. Define decryption conditions

Before we encrypt our data, we have to define the decryption conditions.

Conditions are the requirements for a data recipient to access the plaintext data – i.e. what they will need to prove later to gain decryption rights. There are multiple Condition types we can use here, including predefined conditions such as ERC721Ownership.

The ERC721Ownership condition checks the owner of a given token ID. It can be customized by using the ownerOf contract method and comparing it with the requestor's signature. For more information, see the References section.

We will now specify the condition that must be met to access the data. In this tutorial, we will require that the requester owns an ERC721 token on Ethereum mainnet with a token ID of 5954.

import { conditions } from '@nucypher/taco';

const ownsNFT = new conditions.predefined.erc721.ERC721Ownership({
  contractAddress: '0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D',
  chain: 1,
  parameters: [5954], // We need to specify a token ID here
});

We can create more complex conditions by combining them with CompoundCondition

import { conditions } from '@nucypher/taco';

const conditions = new conditions.compound.CompoundCondition({
  operator: 'and'
  operands: [
    NFTOwnership,
    // Other conditions can be added here
  ]
});

3. Encrypt the plaintext

We're ready to encrypt our plaintext and gate access to the encrypted contents with our conditions, NFTOwnership.

import { encrypt, domains } from '@nucypher/taco';
import { ethers } from "ethers";

const web3Provider = new ethers.providers.Web3Provider(window.ethereum);

const messageKit = await encrypt(
  web3Provider,
  domains.MAINNET,
  message,
  ownsNFT,
  ritualId,
  web3Provider.getSigner() 
);

The resulting messageKit contains the encrypted data and associated conditions.

4. Request decryption

Finally, we will test the conditional access control service by requesting decryption:

import { conditions, decrypt, domains } from '@nucypher/taco';
import { EIP4361AuthProvider, USER_ADDRESS_PARAM_DEFAULT } from '@nucypher/taco-auth';
import { ethers } from "ethers";

const web3Provider = new ethers.providers.Web3Provider(window.ethereum); 

const conditionContext =
  conditions.context.ConditionContext.fromMessageKit(messageKit);
  
// auth provider when condition contains ":userAddress" context variable
// the decryptor user must provide a signature to prove ownership of the wallet address
const authProvider = new EIP4361AuthProvider(
    web3Provider,
    web3Provider.getSigner(),
);
conditionContext.addAuthProvider(USER_ADDRESS_PARAM_DEFAULT, authProvider);

const decryptedMessage = await decrypt(
    web3Provider,
    domains.MAINNET,
    messageKit,
    conditionContext,
);

At decryption time, the requester will be asked to verify their address by signing a message from their wallet. If the requester's address controls the minimum number (or greater) of the specified NFT, they are eligible to receive the requisite number of decryption fragments. By assembling these fragments, they can decrypt the encrypted data and view the plaintext.

{% hint style="info" %} Note that the requester does not need to manually sign the next time they seek access to the data, as the taco client will cache their signature. Fresh plaintexts encrypted under any conditions involving the same wallet address are automatically accessible to any requester who has signed at least once, provided they still fulfill any requisite conditions, and the cached signature has not expired. {% endhint %}

Complete example

This is the complete, end-to-end example of taco integration

import { encrypt, decrypt, conditions, domains, initialize  } from '@nucypher/taco';
import { EIP4361AuthProvider, USER_ADDRESS_PARAM_DEFAULT } from '@nucypher/taco-auth';
import { ethers } from "ethers";

// The data encryptor runs this part
const doEncrypt = async (message) => {
  const web3Provider = new ethers.providers.Web3Provider(window.ethereum);
  const ownsNFT = new conditions.predefined.erc721.ERC721Ownership({
      contractAddress: '0x1e988ba4692e52Bc50b375bcC8585b95c48AaD77',
      parameters: [3591],
      chain: 1,
  });
  const messageKit = await encrypt(
      web3Provider,
      domains.MAINNET,
      message,
      ownsNFT,
      ritualId,
      web3Provider.getSigner()
  )
  return messageKit

// The data recipient runs this part
const doDecrypt = async (messageKit) => {
  const web3Provider = new ethers.providers.Web3Provider(window.ethereum);
  
  const conditionContext =
      conditions.context.ConditionContext.fromMessageKit(messageKit);

  // auth provider when condition contains ":userAddress" context variable
  const authProvider = new EIP4361AuthProvider(
      web3Provider,
      web3Provider.getSigner(),
  );
  conditionContext.addAuthProvider(USER_ADDRESS_PARAM_DEFAULT, authProvider);
    
  const decryptedMessage = await decrypt(
      web3Provider,
      domains.MAINNET,
      messageKit,
      conditionContext,
  );
  return decryptedMessage;
};

// We have to initialize TACo library first
await initialize();
  
const message = 'my secret message';
const encryptedMessage = await doEncrypt(message);
const decryptedMessage = await doDecrypt(encryptedMessage);

if (decryptedMessage === toBytes(message)) {
  console.log('Success!');
}