Client

Every network connection carries a cofhe object with three methods for building a CofheClient. Use createClientWithBatteries in most tests, and the manual path when you need to change the client config. The examples on this page run inside an async describe callback that opens a connection first:

import { network } from 'hardhat';

const { viem, cofhe } = await network.create();
const publicClient = await viem.getPublicClient();
const [walletClient] = await viem.getWalletClients();

Batteries included

cofhe.createClientWithBatteries(walletClient?) returns a client that is ready to encrypt and decrypt. It:

Creates a config for the Hardhat mock environment, with supportedChains: [hardhat] and a zero mocks.encryptDelay.
Creates the client and connects it with the connection’s public client and your wallet client.
Signs a self ACP (Access Control Permission) for the wallet’s address and makes it the active ACP.

const client = await cofhe.createClientWithBatteries(walletClient);

client.connected; // true

Called with no argument, it signs with the first account of the connection:

const client = await cofhe.createClientWithBatteries();

Because the self ACP exists from the start, decryptForView and decryptForTx().withACP() work without any further setup.

Manual setup

Build the client step by step when a test needs a different config, for example a non-zero encryptDelay.

Create the config

const config = await cofhe.createConfig({ mocks: { encryptDelay: 100 } });

cofhe.createConfig wraps createCofheConfig from @cofhe/sdk/node. It sets environment: 'hardhat' and supportedChains: [hardhat], defaults mocks.encryptDelay to 0, and merges your overrides on top.

Create the client

const client = cofhe.createClient(config);

The client is not connected yet: client.connected is false.

Connect it

await client.connect(publicClient, walletClient);

connect takes viem clients directly, so the clients from @nomicfoundation/hardhat-viem pass straight in.

A manually built client also creates a self ACP when it connects, so decryptForView works without extra setup here too.

Several signers

Create one client per wallet. Each client signs its own encrypted inputs and holds its own ACP.

const [alice, bob] = await viem.getWalletClients();

const aliceClient = await cofhe.createClientWithBatteries(alice);
const bobClient = await cofhe.createClientWithBatteries(bob);

An encrypted input is bound to the account that encrypted it. Send the transaction from that same wallet, or the contract reverts with InvalidSigner, which viem reports as the selector 0x7ba5ffb5.

API summary

Method	Returns	Description
`createClientWithBatteries`	`Promise<CofheClient>`	Connected client with a self ACP. Takes an optional `WalletClient` and defaults to the first account of the connection.
`createConfig`	`Promise<CofheConfig>`	Config for the Hardhat mock environment. Takes optional overrides.
`createClient`	`CofheClient`	Unconnected client built from a config.

Using the client

Once connected, the client is the standard SDK client. See:

Introduction

Quick Start

Guides

Hardhat Plugin

Hardhat 3 Plugin

Foundry Plugin

Examples

Reference

Batteries included

Manual setup

Several signers

API summary

Using the client

​Batteries included

​Manual setup

​Several signers

​API summary

​Using the client

Batteries included

Manual setup

Several signers

API summary

Using the client