The Smartcontract Signer is the application that signs messages for Ethereum compatible blockchains.

The signed message will generate a signature of the data, that could be verified in smartcontracts using ecrecover function.

The Unique feature of Smartcontract Signer!

This application keeps privatekeys as the encrypted files. While hiding the privatekeys, the application exposes only one port to interact with outer world.

Thus, it's recommended to set up Smartcontract Signer in an isolated server that has no access to the internet.

While application is not connected to the rest of the world, its recommended to connect to the local network, where Smartcontract Signer exposes only one port.

This way, other applications that interact with the clients could send a data to sign to the Smartcontract Signer through the open port.

Production usage

You don't have to clone the source code in order to use it in production environment.

The built docker images of Smartcontract Signer and RabbitMQ are enough to run this application.

This repository comes with prod branch. This branch contains docker-compose.yml in the docker-prod folder with the links to Smartcontract Signer and RabbitMQ images. You can use it for the production.

So, here are the instructions on how to use it.

1. Clone and checkout the prod branch in your computer.
2. In the root directory, create .env file based on .example.env.
3. In the root directory, create private folder where you will keep the encrypted wallet files.
4. Open the terminal, and go to the smartcontract-signer/docker-prod folder. 4.1. Here, we first need to run the RabbitMQ by typing the following code:

docker-compose up -d mq

4.2 Check that state of the mq service is Up:

doker-compose ps

If it is up, then run the Smartcontract Signer:

docker-compose up -d signer
docker-compose ps 

If both signer and mq services are running successfully, then we can prepare the services to sign messages.

5. Once the containers are running, we need to run the Server which opens the HTTP channel to receive the data to sign. Also, we need to run Signer that will generate a signature with the private keys for the message received from the Server. To do it, enter into the signer container:

docker exec -it signer bash

5.1 Inside the container run the following: node src/cli.js server-start This will start a server.

5.2 Then to start a signer, we need to run the following command: node src/cli.js signer-start This will start a signer.

6. In order to able the Signer, we first need to add encrypted wallet by running

node src/cli.js wallet-create

7. Then we need to load encrypted wallet into the Signer

node src/cli.js signer-add

8. Finally open the browser, and send the POST parameter to the Signer.

with the following JSON body:

{
    "address": "0xC6EF8A96F20d50E347eD9a1C84142D02b1EFedc0",
    "params": [
        {
            "type": "UINT256",
            "value": 3
        }
    ]
}

The address is the wallet address that will sign the message. The params is the array of data to sign. The parameters will be concatenated in the given order.

The Smartcontract Signer supports the following parameter types are:

• UINT8
• UINT256
• ADDRESS
• DECIMAL_18
• DECIMAL_6

Usage

Cli is the main gateway of the applicaion.

• src/gateway.js - enables the RabbitMQ gateway and the Server. it will be the application that creates child processes.

Cli commands:

• cli.js gate-kill shuts down both server and encrypted parameters.
• cli.js server-start enables to receive messages from outside to sign by privatekeys. It is running as the detached child process.
• cli.js server-stop stops the server, preventing to sign messages. Sends the Message to the server to shut it down.
• cli.js signer-start imports the encrypted wallets from /private folder, and enables them to the server. It is running as the detached child process.
• cli.js signer-stop prevents from signing any message.
• cli.js signer-add decrypted wallet is added to the signer.
• cli.js signer-remove erases from signer's list in the signer.
• cli.js wallet-list shows list of loaded encrypted wallets. --all argument lists all wallet names in the /private folder. --unload shows the list of wallets that are not loaded.
• cli.js wallet-create adds the encrypted wallet into the /private folder.
• cli.js wallet-delete removes the encrypted wallet from the /private directory.