​
Prerequisites

Before getting started, ensure you have:

  • A Sequence project with an access key from Sequence Builder
  • Node.js environment
  • Required packages installed:
npm install @0xsequence/auth @0xsequence/network ethers

​
Setting Up the Provider

First, create a provider to connect to the blockchain:

Get your Sequence RPC URL from the Sequence Builder.

import { findSupportedNetwork } from "@0xsequence/network";
import type { NetworkConfig } from "@0xsequence/network";
import { ethers } from "ethers";

export const getProvider = async (chainConfig: NetworkConfig) => {
    const provider = new ethers.JsonRpcProvider(process.env.SEQUENCE_RPC_URL, chainConfig.chainId);
    return provider;
};

​
Signer Options

Sequence supports multiple signer types for secure key management.

​
1. Raw Private Key Signer

This is the most basic signer type. It uses an ethers.Wallet instance to sign transactions.

import { Session } from "@0xsequence/auth";
import { findSupportedNetwork } from "@0xsequence/network";
import { ethers } from "ethers";

export const getLocalSigner = async (chainHandle: string) => {
    const chainConfig = findSupportedNetwork(chainHandle);
    if (!chainConfig) {
        throw new Error(`Chain config not found for chain handle: ${chainHandle}`);
    }

    const provider = await getProvider(chainConfig);
    const walletEOA = new ethers.Wallet(process.env.EVM_PRIVATE_KEY ?? '', provider);
    
    const smartAccount = await Session.singleSigner({
        signer: walletEOA,
        projectAccessKey: process.env.PROJECT_ACCESS_KEY ?? ''
    });

    return smartAccount.account.getSigner(chainConfig.chainId);
};

​
2. Google Cloud KMS Signer

You can use Google Cloud KMS to securely manage your private keys.

1

First install the @0xsequence/google-kms-signer package:

npm install @0xsequence/google-kms-signer
2

You need to setup GCP KMS to get the required env variables. See a guide based on our Sidekick solution here

3

Then, create a Google Cloud KMS signer:

import { GoogleKmsSigner } from "@0xsequence/google-kms-signer";
import { findSupportedNetwork } from "@0xsequence/network";

export const getGoogleKmsSigner = async (chainHandle: string) => {
    const chainConfig = findSupportedNetwork(chainHandle);
    if (!chainConfig) {
        throw new Error(`Chain config not found for chain handle: ${chainHandle}`);
    }

    const googleKmsSigner = new GoogleKmsSigner({
        project: process.env.PROJECT ?? '',
        location: process.env.LOCATION ?? '',
        keyRing: process.env.KEY_RING ?? '',
        cryptoKey: process.env.CRYPTO_KEY ?? '',
        cryptoKeyVersion: process.env.CRYPTO_KEY_VERSION ?? ''
    });

    const smartAccount = await Session.singleSigner({
        signer: googleKmsSigner,
        projectAccessKey: process.env.PROJECT_ACCESS_KEY ?? ''
    });

    return smartAccount.account.getSigner(chainConfig.chainId);
};

​
3. AWS KMS Signer

You can use AWS KMS to securely manage your private keys.

1

First install the @0xsequence/aws-kms-signer package:

npm install @0xsequence/aws-kms-signer
2

You need to setup AWS KMS to get the required env variables. See a guide based on our Sidekick solution here

3

Then, create an AWS KMS signer:

export const getAwsKmsSigner = async (chainHandle: string) => {
    const chainConfig = findSupportedNetwork(chainHandle);
    if (!chainConfig) {
        throw new Error(`Chain config not found for chain handle: ${chainHandle}`);
    }

    const awsKmsSigner = new AwsKmsSigner(
        process.env.AWS_REGION ?? '',
        process.env.AWS_KMS_KEY_ID ?? ''
    );

    const smartAccount = await Session.singleSigner({
        signer: awsKmsSigner,
        projectAccessKey: process.env.PROJECT_ACCESS_KEY ?? ''
    });

    return smartAccount.account.getSigner(chainConfig.chainId);
};

​
Factory Pattern for Signer Selection

You can create a factory function to select the appropriate signer based on environment configuration:

export const getSigner = async (chainHandle: string) => {
    if (process.env.SIGNER_TYPE === 'google_kms') { 
        return getGoogleKmsSigner(chainHandle);
    } 
    if (process.env.SIGNER_TYPE === 'aws_kms') {
        return getAwsKmsSigner(chainHandle);
    }
    // Default to local signer
    return getLocalSigner(chainHandle);
};

If you want to learn more about the KMS Signer libraries, you can read our blog post here.

​
Sending Transactions

Once you have a signer, you can use it to send transactions.

import { getSigner } from "./signer";

async function sendTransaction(chainId: string, to: string, value: string, data: string) {
    // Get the signer for the specified chain
    const signer = await getSigner(chainId);
    
    // Send the transaction
    const tx = await signer.sendTransaction({ to, value, data });
    
    // Wait for the transaction to be mined
    const receipt = await tx.wait();
    
    if (receipt?.status === 0) {
        throw new Error('Transaction reverted');
    }
    
    return {
        txHash: receipt?.hash,
        contractAddress: receipt?.contractAddress,
        txUrl: `https://${chainId}.etherscan.io/tx/${receipt?.hash}`
    };
}

async function sendTransactionBatch(chainId: string, transactions: { to: string, value: string, data: string }[]) {
    // Get the signer for the specified chain
    const signer = await getSigner(chainId);
    
    // Send the transaction batch
    const tx = await signer.sendTransaction(transactions);
    
    // Wait for the transaction to be mined
    const receipt = await tx.wait();
    
    if (receipt?.status === 0) {
        throw new Error('Transaction reverted');
    }
    
    return {
        txHash: receipt?.hash,
        contractAddress: receipt?.contractAddress,
        txUrl: `https://${chainId}.etherscan.io/tx/${receipt?.hash}`
    };
}

With this setup, you can securely connect to multiple blockchain networks and perform transactions from your backend services using Sequence.

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