BrookNet

Decentralised Hacks 2020 for the Elastos Track Submission

Progress

We have demonstrated an on-chain ZK Rollup together with Onchain Randomness of VDF for Random Oracles Proof of Concept and Random DAOs. This is the first implementation of RANDAO + VDF as per the Justin Drake model. We have also implemented an Atomic Token Swap between two Tokens - Fusion Token and Fractal Token. Fusion Ledger is thus a combination of Fusion Oracles and Fractal DAOs.Lack of a secure and scalable end to end integrated frameworks in smart contract-based blockchain protocols and platforms to integrate Cryptographically Verified Ranomness powered Oracles and DAOs into Tokens, Token Swaps, and DApps. Thus our FusionLedger framework is designed for On-chain and Off-chain interaction between real work data and digital world institutions. FusionOracles will represent the real-world data and FractalDAOs represent the digital world institutions like Banks, Treasuries, Markets, etc.Our approach is a workflow from Fusion Oracles to Fractal DAOs. We are tokenizing Fusion Oracles. We are also tokenizing Fractal DAO. We have tokenized Oracles by applying VDF. Thus they are technically random oracles in the cryptographic sense. We have also tokenized DAOs by applying VDF. We can term them Random DAOs. Now we would like to demonstrate how an Auction App powered by Portis SDK can benefit from this Fractal DAO and Fusion Oracles. We also would like to convert the Fusion Rollup Contract to a Matic Child Chain demonstrating the combined scalability architecture of ZK RollUps and Matic Network.

Challenges

We initially faced issues in selecting a uniform solidity compiler version as VFDs were written in 0.5 incremental versions and Open Zeppelin contracts were written in 0.6 incremental versions. Hence we had to migrate some of the contracts from VDF. Likewise, we also faced some issues in implementing Token Swap as the Atomic Swap framework was in a legacy version of Solidity. We also faced some issues in creating an oracle contract from time-series data. We have overcome the solidity version issues by migration techniques. We have finally used the Truffle framework customized for the solidity version 0.6.2 to compile and deploy all the contracts.

Overview

This is a reference implementation of the FusionLedger framework for On-chain and Off-chain interaction between real work data and digital world institutions. FusionOracles will represent the real world data and FractalDAOs represent the digital world institutions like Banks, Treasuries, Markets, etc.

Components

• Fusion Oracles
• Fractal DAOs
• Fusion Forward Manager
• Verifiable Delay Functions
• Auction Apps
• Workflow

Workflow Approach

• Our Workflow is Fusion to Fractal
• Hence Fusion Oracles to Fractal DAO
• We are tokenising Fusion Oracles
• We are tokenising Fractal DAO
• We will tokenise Oracles by applying VDF
• We will tokenise DAOs by applyingb VDF

Tokenisation Approach

• Applying Fractal Token to Fractal DAO
• Importing Fractal Token Contract
• Importing Fractal DAO Contract
• Creating a simple contract to tokenise DAO by tokenising the campaigns and customers in the DAO
• Tokening Fractal DAO at a time, for a activities and aspirations using Fractal Token
• Applying Fusion Token to Fusion Oracle
• Importing Fusion Oracle contract
• Importing Fusion Token contract
• Tokening Fusion Oracle at a time, for a quantity and quality using Fusion Token

Token Swap

FiniteSwap Execution with Fusion Manager after tokenising FractalDAO and FusionOracles

Scalability

Applying ZK RollUps for FusionOracles and FractalDAOs and FusionManager

Inteface Design ( Roadmap )

• Auction App Listing Oracles
• Auction App choosing an Oracle at a time at random
• Auction App Listing DAOs
• Auciton App choosing a DAO at a time based at random

Dependencies

• Node.js
• Truffle.js
• React.js
• Web3.js
• NPM
• node-fetch

References

• ETHEREUM Plasma
• RANDAO
• STARKWARE Veedo VDF
• MATIC NETWORK ChildChain
• PORTIS SHAPESHIFT
• Fusion Scrpts
• Elastos ELA Sidechain

Elastos.ELA.SideChain.ETH

Elastos Sidechain implementation based on Go Ethereum.

Building the source

For prerequisites and detailed build instructions please read the Installation Instructions on the wiki.

Building geth requires both a Go (version 1.7 or later) and a C compiler. You can install them using your favourite package manager. Once the dependencies are installed, run

make geth

or, to build the full suite of utilities:

make all

Executables

The Elastos.ELA.SideChain.ETH project comes with several wrappers/executables found in the cmd directory.

Command	Description
geth	Our main Ethereum CLI client. It is the entry point into the Ethereum network (main-, test- or private net), capable of running as a full node (default), archive node (retaining all historical state) or a light node (retrieving data live). It can be used by other processes as a gateway into the Ethereum network via JSON RPC endpoints exposed on top of HTTP, WebSocket and/or IPC transports. geth --help and the CLI Wiki page for command line options.
abigen	Source code generator to convert Ethereum contract definitions into easy to use, compile-time type-safe Go packages. It operates on plain Ethereum contract ABIs with expanded functionality if the contract bytecode is also available. However it also accepts Solidity source files, making development much more streamlined. Please see our Native DApps wiki page for details.
bootnode	Stripped down version of our Ethereum client implementation that only takes part in the network node discovery protocol, but does not run any of the higher level application protocols. It can be used as a lightweight bootstrap node to aid in finding peers in private networks.
evm	Developer utility version of the EVM (Ethereum Virtual Machine) that is capable of running bytecode snippets within a configurable environment and execution mode. Its purpose is to allow isolated, fine-grained debugging of EVM opcodes (e.g. evm --code 60ff60ff --debug).
gethrpctest	Developer utility tool to support our ethereum/rpc-test test suite which validates baseline conformity to the Ethereum JSON RPC specs. Please see the test suite's readme for details.
rlpdump	Developer utility tool to convert binary RLP (Recursive Length Prefix) dumps (data encoding used by the Ethereum protocol both network as well as consensus wise) to user friendlier hierarchical representation (e.g. rlpdump --hex CE0183FFFFFFC4C304050583616263).
swarm	Swarm daemon and tools. This is the entrypoint for the Swarm network. swarm --help for command line options and subcommands. See Swarm README for more information.
puppeth	a CLI wizard that aids in creating a new Ethereum network.

Running geth

Going through all the possible command line flags is out of scope here (please consult our CLI Wiki page), but we've enumerated a few common parameter combos to get you up to speed quickly on how you can run your own Geth instance.

Full node on the main ELA Ethereum network

By far the most common scenario is people wanting to simply interact with the Ethereum network: create accounts; transfer funds; deploy and interact with contracts. For this particular use-case the user doesn't care about years-old historical data, so we can fast-sync quickly to the current state of the network. To do so:

$ geth console

This command will:

• Start geth in fast sync mode (default, can be changed with the --syncmode flag), causing it to download more data in exchange for avoiding processing the entire history of the Ethereum network, which is very CPU intensive.
• Start up Geth's built-in interactive JavaScript console, (via the trailing console subcommand) through which you can invoke all official web3 methods as well as Geth's own management APIs. This tool is optional and if you leave it out you can always attach to an already running Geth instance with geth attach.

Full node on the ELA testnet network

Transitioning towards developers, if you'd like to play around with creating Ethereum contracts, you almost certainly would like to do that without any real money involved until you get the hang of the entire system. In other words, instead of attaching to the main network, you want to join the test network with your node, which is fully equivalent to the main network, but with play-Ether only.

$ geth --testnet console

The console subcommand have the exact same meaning as above and they are equally useful on the testnet too. Please see above for their explanations if you've skipped to here.

Specifying the --testnet flag however will reconfigure your Geth instance a bit:

• Instead of using the default data directory (~/.ela_ethereum on Linux for example), Geth will nest itself one level deeper into a testnet subfolder (~/.ela_ethereum/testnet on Linux). Note, on OSX and Linux this also means that attaching to a running testnet node requires the use of a custom endpoint since geth attach will try to attach to a production node endpoint by default. E.g. geth attach <datadir>/testnet/geth.ipc. Windows users are not affected by this.
• Instead of connecting the main Ethereum network, the client will connect to the test network, which uses different P2P bootnodes, different network IDs and genesis states.

Note: Although there are some internal protective measures to prevent transactions from crossing over between the main network and test network, you should make sure to always use separate accounts for play-money and real-money. Unless you manually move accounts, Geth will by default correctly separate the two networks and will not make any accounts available between them.

How to topup ELA to ETH

• use compile ELA-Client
• create topup transaction: ./ela-cli wallet -t create --deposit eth_address(ETH address) --amount recharge_value(amount ela units) --fee recharge_fee(fee ela units)
• sign transaction: ./ela-cli wallet -t sign --file to_be_signed.txn -p yourpassword(your keystore password)
• send transaction: ./ela-cli wallet -t send --file ready_to_send.txn

How to withdraw ETH to ELA

• use node console: node
• use contract code:

Web3 = require("web3");
// set web3 uri
web3 = new Web3("http://127.0.0.1:20636");
// set withdraw contract
contract = new web3.eth.Contract([{"constant":false,"inputs":[{"name":"_addr","type":"string"},{"name":"_amount","type":"uint256"},{"name":"_fee","type":"uint256"}],"name":"receivePayload","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"payable":true,"stateMutability":"payable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":false,"name":"_addr","type":"string"},{"indexed":false,"name":"_amount","type":"uint256"},{"indexed":false,"name":"_crosschainamount","type":"uint256"},{"indexed":true,"name":"_sender","type":"address"}],"name":"PayloadReceived","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_sender","type":"address"},{"indexed":false,"name":"_amount","type":"uint256"},{"indexed":true,"name":"_black","type":"address"}],"name":"EtherDeposited","type":"event"}]);
// set eth account address
contract.options.address = deploy_contract_address;
// set account contract keystore info
acc = web3.eth.accounts.decrypt(keystore_content, ketstore_password);   
// call receivePayload function，params：(ELA main chain address，amount(In ela up to convert wei 10000000000)，fee)
cdata  = contract.methods.receivePayload(ELA_address, withdraw_amount, fee).encodeABI();
// gas minimum is 3000000，gasPrice is any value
tx = {data: cdata, to: contract.options.address, from: acc.address, gas: "3000000", gasPrice: "20000000000"};
// send transaction amount(use receivePayload function amount)
tx.value = withdraw_amount;
acc.signTransaction(tx).then((res)=>{
   console.log("coming");
   stx = res;
   console.log(stx.rawTransaction);
   web3.eth.sendSignedTransaction(stx.rawTransaction).then(console)});

Note: ELA testnet server Deploy Contract Address: 0x491bC043672B9286fA02FA7e0d6A3E5A0384A31A ELA mainnet server Deploy Contract Address: 0xC445f9487bF570fF508eA9Ac320b59730e81e503

Configuration

As an alternative to passing the numerous flags to the geth binary, you can also pass a configuration file via:

$ geth --config /path/to/your_config.toml

To get an idea how the file should look like you can use the dumpconfig subcommand to export your existing configuration:

$ geth --your-favourite-flags dumpconfig

Note: This works only with geth v1.6.0 and above.

Docker quick start

One of the quickest ways to get Ethereum up and running on your machine is by using Docker:

docker run -d --name ethereum-node -v /Users/alice/ethereum:/root \
           -p 20636:20636 -p 20638:20638 \
           ethereum/client-go

This will start geth in fast-sync mode with a DB memory allowance of 1GB just as the above command does. It will also create a persistent volume in your home directory for saving your blockchain as well as map the default ports. There is also an alpine tag available for a slim version of the image.

Do not forget --rpcaddr 0.0.0.0, if you want to access RPC from other containers and/or hosts. By default, geth binds to the local interface and RPC endpoints is not accessible from the outside.

Programatically interfacing Geth nodes

As a developer, sooner rather than later you'll want to start interacting with Geth and the Ethereum network via your own programs and not manually through the console. To aid this, Geth has built-in support for a JSON-RPC based APIs (standard APIs and Geth specific APIs). These can be exposed via HTTP, WebSockets and IPC (unix sockets on unix based platforms, and named pipes on Windows).

The IPC interface is enabled by default and exposes all the APIs supported by Geth, whereas the HTTP and WS interfaces need to manually be enabled and only expose a subset of APIs due to security reasons. These can be turned on/off and configured as you'd expect.

HTTP based JSON-RPC API options:

• --rpc Enable the HTTP-RPC server
• --rpcaddr HTTP-RPC server listening interface (default: "localhost")
• --rpcport HTTP-RPC server listening port (default: 20636)
• --rpcapi API's offered over the HTTP-RPC interface (default: "eth,net,web3")
• --rpccorsdomain Comma separated list of domains from which to accept cross origin requests (browser enforced)
• --ws Enable the WS-RPC server
• --wsaddr WS-RPC server listening interface (default: "localhost")
• --wsport WS-RPC server listening port (default: 20635)
• --wsapi API's offered over the WS-RPC interface (default: "eth,net,web3")
• --wsorigins Origins from which to accept websockets requests
• --ipcdisable Disable the IPC-RPC server
• --ipcapi API's offered over the IPC-RPC interface (default: "admin,debug,eth,miner,net,personal,shh,txpool,web3")
• --ipcpath Filename for IPC socket/pipe within the datadir (explicit paths escape it)

You'll need to use your own programming environments' capabilities (libraries, tools, etc) to connect via HTTP, WS or IPC to a Geth node configured with the above flags and you'll need to speak JSON-RPC on all transports. You can reuse the same connection for multiple requests!

Note: Please understand the security implications of opening up an HTTP/WS based transport before doing so! Hackers on the internet are actively trying to subvert Ethereum nodes with exposed APIs! Further, all browser tabs can access locally running webservers, so malicious webpages could try to subvert locally available APIs!

Operating a private network

Maintaining your own private network is more involved as a lot of configurations taken for granted in the official networks need to be manually set up.

Defining the private genesis state

First, you'll need to create the genesis state of your networks, which all nodes need to be aware of and agree upon. This consists of a small JSON file (e.g. call it genesis.json):

{
  "config": {
        "chainId": 0,
        "homesteadBlock": 0,
        "eip155Block": 0,
        "eip158Block": 0
    },
  "alloc"      : {},
  "coinbase"   : "0x0000000000000000000000000000000000000000",
  "difficulty" : "0x20000",
  "extraData"  : "",
  "gasLimit"   : "0x2fefd8",
  "nonce"      : "0x0000000000000042",
  "mixhash"    : "0x0000000000000000000000000000000000000000000000000000000000000000",
  "parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
  "timestamp"  : "0x00"
}

The above fields should be fine for most purposes, although we'd recommend changing the nonce to some random value so you prevent unknown remote nodes from being able to connect to you. If you'd like to pre-fund some accounts for easier testing, you can populate the alloc field with account configs:

"alloc": {
  "0x0000000000000000000000000000000000000001": {"balance": "111111111"},
  "0x0000000000000000000000000000000000000002": {"balance": "222222222"}
}

With the genesis state defined in the above JSON file, you'll need to initialize every Geth node with it prior to starting it up to ensure all blockchain parameters are correctly set:

$ geth init path/to/genesis.json

Creating the rendezvous point

With all nodes that you want to run initialized to the desired genesis state, you'll need to start a bootstrap node that others can use to find each other in your network and/or over the internet. The clean way is to configure and run a dedicated bootnode:

$ bootnode --genkey=boot.key
$ bootnode --nodekey=boot.key

With the bootnode online, it will display an enode URL that other nodes can use to connect to it and exchange peer information. Make sure to replace the displayed IP address information (most probably [::]) with your externally accessible IP to get the actual enode URL.

Note: You could also use a full fledged Geth node as a bootnode, but it's the less recommended way.

Starting up your member nodes

With the bootnode operational and externally reachable (you can try telnet <ip> <port> to ensure it's indeed reachable), start every subsequent Geth node pointed to the bootnode for peer discovery via the --bootnodes flag. It will probably also be desirable to keep the data directory of your private network separated, so do also specify a custom --datadir flag.

$ geth --datadir=path/to/custom/data/folder --bootnodes=<bootnode-enode-url-from-above>

Note: Since your network will be completely cut off from the main and test networks, you'll also need to configure a miner to process transactions and create new blocks for you.

Running a private miner

Mining on the public Ethereum network is a complex task as it's only feasible using GPUs, requiring an OpenCL or CUDA enabled ethminer instance. For information on such a setup, please consult the EtherMining subreddit and the Genoil miner repository.

In a private network setting however, a single CPU miner instance is more than enough for practical purposes as it can produce a stable stream of blocks at the correct intervals without needing heavy resources (consider running on a single thread, no need for multiple ones either). To start a Geth instance for mining, run it with all your usual flags, extended by:

$ geth <usual-flags> --mine --minerthreads=1 --etherbase=0x0000000000000000000000000000000000000000

Which will start mining blocks and transactions on a single CPU thread, crediting all proceedings to the account specified by --etherbase. You can further tune the mining by changing the default gas limit blocks converge to (--targetgaslimit) and the price transactions are accepted at (--gasprice).

Contribution

Thank you for considering to help out with the source code! We welcome contributions from anyone on the internet, and are grateful for even the smallest of fixes!

If you'd like to contribute to Elastos.ELA.SideChain.ETH, please fork, fix, commit and send a pull request for the maintainers to review and merge into the main code base. If you wish to submit more complex changes though, please check up with the core devs first on our gitter channel to ensure those changes are in line with the general philosophy of the project and/or get some early feedback which can make both your efforts much lighter as well as our review and merge procedures quick and simple.

Please make sure your contributions adhere to our coding guidelines:

• Code must adhere to the official Go formatting guidelines (i.e. uses gofmt).
• Code must be documented adhering to the official Go commentary guidelines.
• Pull requests need to be based on and opened against the master branch.
• Commit messages should be prefixed with the package(s) they modify.
  • E.g. "eth, rpc: make trace configs optional"

Please see the Developers' Guide for more details on configuring your environment, managing project dependencies and testing procedures.

License

The Elastos.ELA.SideChain.ETH library (i.e. all code outside of the cmd directory) is licensed under the GNU Lesser General Public License v3.0, also included in our repository in the COPYING.LESSER file.

The Elastos.ELA.SideChain.ETH binaries (i.e. all code inside of the cmd directory) is licensed under the GNU General Public License v3.0, also included in our repository in the COPYING file.