jpantunes/code

👾 Implementation of cryptoeconomics coding project

👾 Coding Project

This repository contains the coding project which accompanies the cryptoeconomics.study course. This includes implementing a payment processor blockchain, proof of work, proof of stake, and Plasma.

Much of the code here will be reviewed in online videos which karl.tech and other community members put together. Links to these tutorial videos coming soon!

Contributing

Suggestions and contributions are extremely welcome. For instance, there might be room in the curriculum to implement a simple state channel as well. There is also room for contributors to optimize the code as well as create visualizations. Check out the open issues and project board and help out! :)

Coding Project Outline

Node Implementation

• Account Model
• UTXO Model

Adding Networking

• Network Simulator with nodes sending each other “hello world”
  • Network simulator implementation: https://github.com/cryptoeconomics-study/code/blob/master/c2_NetworkDoubleSpends/networksim.js
• Nodes sending transactions
  • Send transactions until invalid tx found - https://github.com/cryptoeconomics-study/code/blob/master/c2_NetworkDoubleSpends/invalidWithHonestNodes.js
  • Intentionally double spend - https://github.com/cryptoeconomics-study/code/blob/master/c2_NetworkDoubleSpends/doubleSpend.js

Adding Proof of Work block proposal

• Nodes sending blocks
  • Instead of each node generating and sending a transaction, generate a transaction and put it in a block which point to previous blocks
  • Create blocks only one the longest known chain of blocks which the node has
  • Clients still apply all transactions, whether or not they are on the longest chain.
• Proof of work on the blocks
  • Add anti-spam protection with proof of work on each block
  • See implementation here: https://github.com/karlfloersch/lessons/blob/master/lessons/02_proofOfWork.js#L16-L26
• Fork choice
  • Only apply transactions which are contained in the longest chain
  • Lazily apply these transactions (create function getState() which applies all the transactions in the chain and returns the resulting state object.
• Minder // client separation
  • Add Miner class which collects txs & makes blocks
  • Add Client class which generates & sends transactions

Adding Proof of Stake Finality (FFG)

• Add validator class
• Add deposit transaction which locks coins
• Add withdraw transaction which unlocks coins (after some delay)
• Add vote() which votes on the current epoch, if more than ⅔ vote then the block is finalized
• Update the fork choice rule to not revert finalized blocks, and accept a ‘starting block’ blockhash.

Instead Implement as Plasma with a Central Operator

• Create rootChain.sol which accepts block hashes
• Create merkleProof.sol which validates merkle proofs
• Using https://github.com/ethereum/py-evm write tests which:
  • Deploy the merkle prover & root chain
  • Deposit test ETH to the root chain, creating a new Plasma Cash coin
  • Submit merkle proofs to the root chain contract which transfer the coin
  • Exit the coin with a different account than the one that deposited
• Add exit challenges

Stretch Goals!

• Network message propagation visualization
  • Using https://github.com/feross/p2p-graph as a base, create a visualization which shows which nodes are receiving messages and which nodes are sending messages. These messages are sent and received in steps, so you can change the color of the little dots corresponding to each state. Get creative :)

Example of current network visualization: