ykankaya / example-eth-wallet-in-dotnet

An example wallet for Ethereum, accompanying this Medium article: https://medium.com/@jkirsteins/writing-an-ethereum-wallet-for-fun-e82a05322ae2

Demo Ethereum Wallet

This is a barebones Ethereum wallet, which supports:

• generating a new secp256k1 private key
• saving and loading its state from JSON
• synchronizing with Infura's Rinkeby node
• sending transactions

Values denominated in wei are represented using the BigInteger type.

Values denominated in ether (used in interaction with the user) are represented using the decimal type.

This wallet was written to accompany this Medium article: Writing an Ethereum Wallet for Fun.

Dependencies

The main dependency is the Nethereum library, which handles key generation, and Ethereum JSON RPC function calls.

Structure

The Wallet is a partial class split across 3 files:

• Wallet.SerializableProperties.cs contains the properties that will be saved to/loaded from JSON
• Wallet.LoadingAndSaving.cs contains code that pertains to wallet generation, loading, and saving
• Wallet.EthereumInteraction.cs contains code that interacts with the Infura Rinkeby node using the Nethereum library

The Wallet - upon creation - will query the Infura Rinkeby node for the latest known block, and store it as the last known block.

Afterwards, it can be synchronized - every synchronization action will load blocks between the last known block of the wallet (stored in the JSON file) and the last known block as reported by the Infura's Rinkeby node. For every block it will download every transaction, and look if from/to values correspond to our wallet's address. If they do, the found transactions will be stored in the JSON file.

The application is structured as a CLI application, which presents a menu with the available options:

• listing known transactions (found by the synchronization action, and stored in the local JSON file)
• sending a transaction
• performing a new synchronization action

The file Program.cs mainly deals with the UI, and is pretty boring.

ConsoleEx is a class which contains convenience methods for prompting values from the user using the command-line (e.g. helpers for querying for decimals, BigIntegers, optional BigIntegers and Ethereum addresses)

Extensions

There are a couple of extensions:

• StringExtensions.cs contains code for verifying that a string is a hex string representing a valid 20-byte value. This is used for verifying that the user entered a valid Ethereum address, when sending a transaction.
• DecimalExtensions.cs and BigIntegerExtensions.cs contain code for converting between wei and ether denominated values (BigIntegers and decimals respectively).