Ethereum! Why GO there?

a.k.a. hacking the blockchain

9 Mar 2018

Tags: Ethereum, Solidity, Smart Contracts, Golang, Gophercon India

Dave Appleton

Lead blockchain developer, HelloGold

https://hellogold.com

@AppletonDave

* My aims for being here

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- To share what excites me about the ethereum blockchain

- To inspire some of you to consider working on blockchain projects

- To explain why being a go developer puts you in a special place

* Todays Agenda

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- Introduction (me)

- The Blockchain in five minutes

- ethereum and smart Contracts

- The go-ethereum code base

- Native Dapp bindings for smart contracts

- What is ethereum used for today?

* Introduction (me)

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- Englishman living in Southeast Asia for 36 years

- Programming since 1968

- background in instrumentation, machine vision

- Blockchain dev since 2014

- Lead blockchain developer at HelloGold, Malaysia

- Blockchain Consultant

* The blockchain in five minutes

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* What is a blockchain ?

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- signed transactions

- Put into signed blocks

- Which are added to a chain (list) by signed links

- which is distributed all over a decentralised network

- in a manner such that all the independant nodes that operate the network agree the whole thing to be valid (consensus)

* Transactions ?

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- Anything that can change the state of something.

- A transfer of value or data

{

From : Dave

To : Alice

Value : 100

Data : "Happy Birthday Alice. Buy yourself something nice"

}

Web analogy:

.code demo_code.txt /start REST OMIT/,/end REST OMIT/

Current state = sum of all previous transactions

* Thought of the day....

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"Young man, in mathematics you don't understand things. You just get used to them."

.caption John von Neumann.

* Digital Signatures

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- a small change in the content causes a huge change in the result.

.play hashBaby.go /start main OMIT/,/end main OMIT/

If we encrypt the hash value using public key encryption

we can prove it was from me

and make it unforgeable

* Public Key encryption in 20 seconds

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- create a truly random a private key

- public key (address) derived from private key

- something encrypted by private key can be read with public key

_or_

- you can derive the signer from the encrypted data

- encrypting the hash, ensures that the hash, thus the document is unchanged

- and ensures that the signer is who they say they are.

.code demo_code.txt /start RESTx OMIT/,/end RESTx OMIT/

* signing

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* Into blocks

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* In a manner that everybody agrees (Consensus)

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- the details are not terribly relevent in our context except

- design of consensus algorithm ensures that no one node makes all the decisions

- makes it virtually impossible for anybody to modify the past records in the chain

- means that each node has an identical copy of the state of the blockchain

* Etherscan

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- have a look at https://etherscan.io

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* Etherscan

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- the Google of the blockchain

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* Wallets

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* Easy ways to access your account/balance?

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Something that *performs* *one* *or* *more* *of*

- managing keys

- creating transactions

- signing transactions

is often called a Wallet. (but it isn't)

* What makes Ethereum special ?

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* Introducing Smart Contracts

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- remember the "data" field?

- a way to give certain blocks of byte code an address...

- compilers

- byte-codes

- virtual machines....

- function routing...

- state variables...

Running on thousands of nodes

* What are smart contracts

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* And the whole thing is agreed and transparent

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* OK - so where does GO come in?

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- reference design is written in GO

- designed to allow linking into codebase

- while most people concentrate on the browser

- we have a framework to allow servers to access the blockchain

* The reference ethereum node implementation is.....

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* How popular is the go-ethereum repo?

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* What a smart contract looks like

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https://remix.ethereum.org

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* Well that was fun but what has that to do with Go?

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* With the de-facto ethereum client written in go

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- You can interact a low level (analysis of logs)

for _, log := range logs {

address := common.BytesToAddress(log.Data[12:32])

count, _ := strconv.ParseInt(common.Bytes2Hex(log.Data[32:]), 16, 64)

fmt.Println(log.BlockNumber, " : Thump(", address.Hex(), ",", count, ")")

}

- or a higher level with ABIGEN binding your contract

.code go/gopherconRead/gopherconRead.go /start OMIT/,/end OMIT/

* Viewing past events using ABIGEN

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.play go/gopherconRead/gopherconRead.go /long OMIT/,/end OMIT/

* Reading the contract's status using ABIGEN

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.play go/reader/reader.go /start OMIT/,/end OMIT/

* Sending a transaction to the contract using ABIGEN

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.play go/hitMe/hitme.go /start OMIT/,/end OMIT/

:-)

* Simulated Backend

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- Connect to a local one-step blockchain - i.e a chain with no history

- excellent for testing purposes (a lot faster)

.code go/simulateandtest/test.go /startClient OMIT/,/endClient OMIT/

- uses the same back EVM as geth

* But There's something special about ethereum

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- The "crypto" has attracted its fair share of scams / money grabs / etc

- Ethereum provides a platform for transparency in projects

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* HelloGold

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- S.E. Asian Financial Crisis

- Bank Negara report 75% cannot raise USD 200 in a Crisis

- Savings products should not only be for the wealthy

- Founded by former CFO of World Gold Council Robin Lee

* Giveth

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- Framework for Charitable fundraising and disbursal

- Transparency

- Hold projects to milestones

* Sentinel Chain

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* Summary

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- There is a niche for go programmers in the ethereum space

- You will have a toolset unmatched by the main group of programmers

- Your lives will never be the same again