Blockchain Basics

Blockchain's promises

"Sharing Economy" of
Uber, Airbnb

Centralized user data,
siloed Facebook, Google

Peer to Peer
+ no middlemen

Self-sovereign
user data

Internet of
Information

Crypto enthusiasts see the new layer of trust and value as Web3.0

Internet of
Value

"Ethereum is an open-source,
 public, blockchain-based
 distributed computing
 platform featuring smart
 contract functionality"

Ethereum Blockchain

Programmable
money:
Smart Contracts

Decentralized
P2P Network

Immutable Global Ledger

Cryptographically signed updates

Consensus
without a central authority

Censorship-resistant

Public-Private Keys

Native token as currency

Ethereum - Global or Private

Private Consortium
Blockchain
(permissions, privacy, speed)

Global Public
Blockchain

BLOCKCHAIN

Timestamps

Currency

Digital Signatures

Accounts

Immutable Ledger

Blockchain Accounts

Account Address derived from private key
(independent from the network)
Accounts exist on chain only after sending / receiving a transaction

BLOCKCHAIN

Timestamps

Currency

Digital Signatures

Accounts

Immutable Ledger

Transactions cost "gas" per computation step and for storage
Prevents spam
Pays "miners" to run peer nodes

Transactions

Transaction

Transactions, Blocks & Chaining

"Writes" to blockchain require private key to sign transactions
Blocks
- contain hash of last block
- created every ~14 seconds in Ethereum

time

Miners compete to compute next block to earn Gas

BLOCKCHAIN

Timestamps

Currency

Signatures

Accounts

Ledger

Smart Contracts

Run automatically when certain conditions are met
Can send/receive funds like accounts
Have address like accounts

contract CrowdFund
 if time_is_up && balance > $10,000
   move balance to crowdfund_account
 else
   return donation to original_donor

(pseudocode)

are programs with code and state stored on the blockchain

Smart Contracts

ETHEREUM

Timestamps

Currency

Signatures

Accounts

Ledger

Smart Contracts

Registries

Maps data to an address e.g. an owner
Programmatically an array stored in a smart contract
Can define permissions, ownership, tokes etc...
Ethereum Name Service (ENS) maps something.eth => address

Registries

ETHEREUM

Timestamps

Currency

Signatures

Accounts

Ledger

Smart Contracts

Registries

Multi-party Signatures

Multiple account holders can sign
Safety for spending large amts or key recovery

Multi sig Wallets

ETHEREUM

Timestamps

Currency

Signatures

Accounts

Ledger

Smart Contracts

Registries

Multi-party Signatures

Tokens

ERC-20 Tokens
fungible (replaceable) tradable assets (a banknote, stock)

ERC-721 Non-fungible Tokens

unique tradable assets (a Van Gogh painting or CryptoKitty)
Categories of Tokens
payment tokens, investment tokens, consumer utility tokens

Tokens

ETHEREUM

Timestamps

Currency

Signatures

Accounts

Ledger

Smart Contracts

Registries

Multi-party Signatures

Tokens

Oracles

Real world data to use in smart contracts
Input must be agreed to, trustworthy, multiple sources
e.g. current price of X, location of Y

off-chain input

Ethereum Community

Discussions on Github
- Ethereum Improvement Proposals (EIPs)
- Ethereum Requests for Comment (ERCs)
https://www.ethereum.org/foundation
https://ethereum-magicians.org

COMMUNITY
CREATING
STANDARDS

Blockchain
Applications

Blockchain Applications

Industry & Finance

Money transfer, micropayment, paywalls
Decentralized exchanges, finance, stable coins
Supplychain asset tracking
Digital assets, licensing (music, images, video)
Incentivized content (media)
Shared ownership (asset tokens)

https://www.eublockchainforum.eu/noteworthy/articles

Public & Social Services

Community currencies
Digital signatures
Public registries (land registries, DNS, identity)
Decentralized governance, voting, budgeting

Subscription Model

ERC-948 Recurring Subscription

Subscription smart contract

User consents to funds withdrawn every time_period by service_address
User can remove consent at any time
Provider of service_address may remove funds every time_period if tokens are available and time_period has passed since last withdrawal

User

Provider

?

Digital Identity Today

Is proprietary / Isn't self owned

Facebook / Google
Credit cards, Bank accounts
~~Equifax~~ -> Random hackers
State IDs / Passports

You pay for your "free" online identity with privacy

You can be excluded ("You may leave if you don't like the new Terms & Conditions")

Self Sovereign Identity

Portable Decentralized identifier (DID)

You create a claim:
"My address is 1 Metropolitan Av, Brooklyn"
Others attest your claim:
"New York State verifies person registered at this address with the official NYS signature"
As a developer you would chose which attestations you consider trustworthy
In the long run Drupal might use DID data or verify claims of users

Asset tokenization
sharing + incentives

Tokenize a tractor in a crowd sale
Agree on rules of usage e.g. A tractor-token holder:
- gets 100 tuktuk-tokens per year
- can buy tractor-time by placing tuktuk-tokens on its calendar
- can trade tuktuk-tokens with other tractor token holders
- can rent out the tractor and vote how to spend funds
community incentivized to keep tractor tokens valuable and tractor in good shape

Drupal Ethereum Module

Drupal Ethereum Module
Overview

Semi-decentralized Architecture
Ethereum PHP library
Ethereum Sign-up
Ethereum User Connector - registry contract
Frontend UX challenges
Managing smart contracts & event triggers

Launch example site using Docker

https://github.com/digitaldonkey/docker-drupal-ethereum

Development goals

Framework to develop Ethereum applications with Drupal

Ready for pioneers to get started

Frontend agnostic

many wallets and signing tools

Goal is out-of-the-box modules + good use cases

Backend agnostic

work with any Ethereum client or service

Semi-decentralized

Ethereum decentralized apps (dapps) are on a hard UX road to serverless

Current Web

Ideal Decentralization

How to connect Drupal and Ethereum?

Semi-decentralization

Client side signing using Transaction-signers

Server just pulls data from blockchain

Architecture challenges

Transaction Signers
Javascript API

Drupal

Ethereum PHP
library

Ethereum Clients or Services

Ethereum

Push Transaction
Independently

Infura.io API

Etherscan API

Ethereum Nodes

Other providers

Ethereum-PHP Library

Abstracts the Ethereum JSON RPC API
strict Datatypes, Cryptographic functions
SmartContract Objects
Contract Event decoding
Testing against smart contracts

Ethereum Nodes

https://github.com/digitaldonkey/ethereum-php

API documentation: http://ethereum-php.org

Mapping Ethereum to Drupal

Infrastructure modules

Accounts
Map Accounts/Addresses to Drupal Accounts
➡ "Ethereum Identity for a known user group"
Experiment on connecting identity
Ethereum Signup / Ethereum User Register

Smart Contracts

Manage deploy as Drupal Admin

Provide ABI to process data in Drupal & frontend

Let Blockchain Events trigger PHP actions

Ethereum Smart Contract Entity

Servers (Ethereum Nodes)

Manage and Connect to Ethereum-nodes
Manage Networks IDs
Server Status Page

Ethereum main module

Transactions Signing

Provide contract ABI in frontend and Web3js

Let Drupal know about Blockchain actions

Provide default UI and web3Ready() in front end
Transaction Signers (web3)

Two Signup modules?

Ethereum Signup

Challenge/response authentication
No blockchain interaction - no gas
Just private-public keys
Uses external auth module

Ethereum User Connector

Smart contract with User Registry
Can be changed to a paywall
Example module for contract interaction

Ethereum Signup

Text

Text + Private Key => Signature
Text + Signature Text => Ethereum Address

Ethereum User Register

Signing Transactions

Signing on Frontend
- Literally the key in the user's hand
- UX challenges
- lost keys are lost forever
Signing on PHP backend
- Hosting private keys turns your server into a honey pot
- multi-sig contracts can help secure

Popular Tools

private key UX is hard

Browser Extensions

Hardware Wallets

Mobile Wallets & Signers

Desktop Wallets

Cloud Wallets

"Web of wallets"

by Bobby Dresser (uPort)

Web3 browser wars?

The Front-end challenge

How to help users not lose their key?
Deal with Identity proxy contracts
Integrate multiple wallets
⇢ allow users to chose, increase browser support
Is the user/wallet on the right network?
Unlocked account required?
How to onboard new users, which have no wallet?

⇢ Experiment with UX interactions
⇢ Develop standards for Dapp interaction

Transaction signer module

Loading TX-signers config based to allow:
- experimentation on different approaches
- define different security levels based on use case
Abstract and unify Ethereum UX
Provide a minimal API for Frontend development
Currently one TX signer "Mascara"

Manage Contracts in Drupal
Provide Contract ABI for frontend and Backend
Handle Contract Events
Import from Truffle

Smart contract Module

Listening to Blockchain state change in PHP

web3.eth.subscribe() and web3.eth.filter() are not consistently implemented/accessible
Process all Blocks with cronjob and process relevant Events
GraphQL solution (query language as API) https://github.com/ConsenSys/ethql
Currently: Frontend transaction-hash-ajax solution

Smart contract EventProcessor

Smart contract Event
processor flowchart

What?

Emit an Event in you Solidity contract code e.g in RegisterDrupal->newUser()
Add a "on"-EventHandler in your module src/Plugin/SmartContract

ethereum_user_connector/src/Plugin/SmartContract/RegisterDrupal.php
Trigger a web3 action like this.contract.methods.newUser(...)
Submit transaction hash to Drupal.behaviors.txHash.submit(TxHash, callback)
Handle response feedback in javascript callback()

  class RegisterDrupal extends SmartContract {
    public static function onAccountCreated(EmittedEvent $event) {
      $hash = $event->getData()['hash'];
      $event->setResponse($controller>verifyUserByHash($hash));
    }
  }

  emit AccountCreated(msg.sender, hash);

Architecture summary

Lots of Thanks to early
contributors & testers

so far 27 pull requests merged

(Commits/PRs stats refer to the various involved projects and may not be up to date)

Questions & Thank You

Tweet about #DrupalEthereum
Run an example https://github.com/digitaldonkey/docker-drupal-ethereum
BOF: Wednesday 11:30-12:15 2.08 platinum
Join discussion, contribute and ★ repos on Github
https://github.com/digitaldonkey/ethereum

thorsten.krug@consensys.net
@digitaldonkey09

The development of Drupal Ethereum Module
Has been sponsored by ConsenSys
@ConsenSys

https://consensys.net

https://slides.com/digitaldonkey/drupaleurope