KMS EVM Signer

This project provides a way to sign EVM transactions using AWS KMS (Key Management Service) with an asymmetric key. It leverages AWS KMS to secure private key management while enabling EVM-compatible signatures.

For a deeper understanding of the underlying mechanics, refer to the detailed guide.

Pre-Requisites

Before getting started, ensure you have the following:

• Node.js
• An AWS Account

Note: Ensure you are running these commands in a bash terminal with your AWS credentials configured.

Setup Environment Variables

Create a .env file at the root of the project based on the provided .env.example template.

cp .env.example .env

Replace the placeholder values in the .env file with your own configuration:

• AWS_REGION - The AWS region where your KMS key is located.
• KMS_KEY_ID - The ID of the KMS Asymmetric key used for signing (If you already have a KMS key).
• RPC_PROVIDER_URL - The URL of the Ethereum-compatible RPC provider. You can use Hardhat's default URL (http://localhost:8545) for local testing.

Install Dependencies

Run the following command to install the project dependencies:

npm install

Create Asymmetric KMS Key

If you don't already have an AWS KMS key, you can create one by running:

npm run create-key

Once the key is created, update your .env file with the KMS_KEY_ID value.

Run End-to-End Test

This test will deploy a simple smart contract, sign a transaction using KMS, and broadcast it to your RPC_PROVIDER_URL.

npm run test -- --silent --verbose

Get KMS Key Info

You can retrieve the public key and address of the KMS key by running the get-key-info script.

npm run get-key-info

Sign Your Own Transaction

You can sign a custom transaction by running the sign-transaction script. First, update the transaction object in the ./scripts/sign-transaction.mjs file with the transaction details.

npm run sign-tx