Simple Storage Solidity

Learning exercise project to deploy and interact with a smartcontract using ethers.js.

• Simple Storage Solidity
• Smartcontract
• Requirements
• Compiling
• Blockchain
• Deploy (and interact)
• Security improvement
  • Set enviromental variables at execution time
  • Encrypt the key
• Typescript

Smartcontract

The smartcontract that is used is a simple implementation of a contract where you can change the value of a number saved on the blockchain. You can also save the number associated to a person.

Requirements

To use the following repository you need to have installed this packages:

• git
  • You'll know you did it right if you can run git --version and you see a response like git version x.x.x
• Nodejs
  • You'll know you've installed nodejs right if you can run:
    • node --version and get an ouput like: vx.x.x
• Yarn instead of npm
  • You'll know you've installed yarn right if you can run:
    • yarn --version and get an output like: x.x.x
    • You might need to install it with npm
• ganache
  • You can alternatively use ganache-cli or hardhat

Compiling

To compile the solidity code solc is used

yarn add solc

if you are using in your contract a solidity version older than the latest you can type

yarn add [email protected]

Finally, to compile the solidity code run the following command

yarn solcjs --bin --abi --include-path node_modules/ --base-path <base-path> -o <output path> <solidity-file-name>

it is easier to add this line in the package.json file.

{
    "scripts": {
        "compile": "<compile-command>"
    }
}

Blockchain

This repo can work with any EVM compatible blockchain. To connect to a blockchain you need an RPC_URL.

For developement purpouses we'll use a local enviroment as ganache.

Deploy (and interact)

To deploy the contract is enough to run the command

node deploy.js

Make sure to have set the RPC_URL and the PRIVATE_KEY in the .env file.

IMPORTANT -> remember never to push the .env file to github or never make it public. Add a .gitignore file!

Security improvement

If you are worried you might leak in some way your .env

Set enviromental variables at execution time

you can run the script as this without the need of any file

RPC_URL=<rpc url> PRIVATE_KEY=<private key> node deploy.js

Encrypt the key

If you don't wont to insert your enviromental variables every time but you still don't want to show the private key to everyone who has access to your project the solution would be to encrypt the key.

The steps to follow are:

• Insert the PRIVATE_KEY and a PASSWORD in .env or at execution time
• Run the encrypt script

node encryptKey.js

• The output will be saved in .encryptedKey.json
• Delete PRIVATE_KEY and PASSWORD from .env
• Now you can run the deploy script as this

PASSWORD=<your password> node deploy-encrypted.js

after the execution is suggest to run

history -c

to delete the terminal history so it is not possible to find out what the password used is.

Typescript

There is a typescript compatible version of the code on the typescript branch

It works exatly the same, you should execute commands replacing node with ts-node

ts-node <file name>