/consensys-dev-bootcamp

Projects from the 2020 ConsenSys Blockchain Developer Bootcamp

Primary LanguageJavaScript

Consensys Blockchain Developer Bootcamp 2020

ConsenSys Certified Ethereum Developer

Coding Python3 Blockchain From Scratch - blockchain.py

  • Implemented simple proof-of-work algorithm similar to HashCash
  • Deployed Python Flask to communicate with blockchain via REST API
  • Used Postman to interact with blockchain (create new transaction, mine new block, return full blockchain)
  • Introduction to consensus algorithms (checking for longest chain)

Generating Ethereum Accounts in Javascript

  • Introduction to public key cryptography and digital signatures
  • Generated a private key, derived public keys from the private key and verified associated accounts

Using Geth (Go-Ethereum)

  • Geth (Go-Ethereum) is a command line interface for running a full Ethereum node implemented in Go

  • Used Geth to mine real Ether, transfer funds between addresses, create contracts, send transactions, and explore block history

  • Learned to navigate the geth javascript console

  • Created private blockchain with proof of work consensus mechanism (test-private-blockchain)

    genesis.json

    • config: defines settings for private blockchain
    • chainId: identifies blockchain
    • alloc: allows creation of addresses and fills accounts with Ether when the blockchain is initialized (left empty to fill accounts with mined Ether)
    • difficulty: defines mining target for discovering a block hash, building on previous block's timestamp and difficulty (value fluctuates to maintain target)
    • extraData: optional 32-byte value to embed additional info
    • gasLimit: sets chain-wide limit on gas expenditure per block
    • parentHash: keccak256 hash of parent block's header
    • timestamp: output of Unix time() at block's creation (calculated difficulty), allowing verification of block order on chain
    • Created new account
    • Mined private chain
    • Sent transaction
    • Verified balance

  • Created private blockchain with proof-of-authority consensus mechanism (geth-poa)

    • Implemented native geth proof-of-authority protocol clique
    • Configured clique via puppeth for creating custom genesis blocks
    • Used bootnode to act as the router/hub between nodes
    • Launched node1 (mining node) with genesis block
    • Launched node2 and node3 to interact with blockchain
    • Sent and verified transactions between nodes

Writing Smart Contracts

Proof of Existence (proof-of-existence)

  • Implemented ganache-cli for development blockchain
  • Hands-on practice using Truffle's create, migrate, console
  • Created three versions: one proof, array of proofs, mapping of proofs
  • Deployed to Rinkeby testnet via Infura

Multi-Signature Wallet (MultiSignatureWallet.sol)

  • Multisignature wallet: an account requiring some m-of-n quorum of approved private keys to approve a transaction before executing
  • Learned how to handle complex interactions between multiple users on one contract
  • Learned to avoid loops and implement voting
  • Audited for attacks on smart contracts
  • Learned best practices for implementing modifiers, events/emit, index keywords
  • Hands-on practice using Truffle's develop to interact with contract

Exercise: SimpleBank

  • Setup banking functions with getBalance, enroll, deposit, withdraw
  • Implemented through mapping, event references

Exercise: SupplyChain

  • Imitated standard supply chain functions with ForSale, Sold, Shipped, Received
  • Implemented through mapping, struct, enum, event, modifier