@oasisprotocol/sapphire-viem-v2

A plugin for Viem 2.x that encrypts transactions, gas estimations and calls to the Oasis Sapphire network to enable end-to-end encryption between the dApp and smart contracts. It provides three functions which can be used together or separately, see the guides below for usage instructions:

• sapphireHttpTransport - Transport that intercepts & encrypts requests.
• wrapWalletClient - Wraps a WalletClient, to provide encryption.
• createSapphireSerializer - Transaction serializer, that encrypts calldata.

Usage

Add the package to your project:

npm install @oasisprotocol/sapphire-viem-v2 viem@2.x
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For local testing the chain configuration for sapphireLocalnet is available in the @oasisprotocol/sapphire-viem-v2 package installed above. The Sapphire mainnet and testnet configurations are available in viem/chains:

import { sapphireLocalnet } from '@oasisprotocol/sapphire-viem-v2';
import { sapphire, sapphireTestnet } from 'viem/chains';
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Encryption

Use the sapphireHttpTransport() transport to automatically intercept and encrypt the calldata provided to the eth_estimateGas, eth_call and eth_sendTransaction JSON-RPC calls.

Transaction calldata will be encrypted while using the in-browser wallet provider (window.ethereum) because this uses the eth_sendTransaction JSON-RPC call to sign transactions.

[!IMPORTANT] To encrypt transactions when using a local wallet client you must not only provide the transport parameter, but must also wrap the wallet client.

This example creates local wallet that is then wrapped with wrapWalletClient which replaces the transaction serializer with one which performs Sapphire encryption:

import { createWalletClient } from 'viem'
import { english, generateMnemonic, mnemonicToAccount } from 'viem/accounts';
import { sapphireLocalnet, sapphireHttpTransport, wrapWalletClient } from '@oasisprotocol/sapphire-viem-v2';

const account = mnemonicToAccount(generateMnemonic(english));

const walletClient = await wrapWalletClient(createWalletClient({
    account,
    chain: sapphireLocalnet,
    transport: sapphireHttpTransport()
}));
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Be careful to verify that any transactions which contain sensitive information are encrypted by checking the Oasis block explorer and looking for the green lock icon.