ethereum

From there to here, and onwards yonder

Dr. Gavin Woodco-founder and lead developer, ethereum project

Overview

DecentralisationConsensusBlockchain

BitcoinDirectionEthereum

Hacking Society

The problem

Agreement necessary for collaboration.

Internet is great for comms but...

Too easy to lie.

The old solution

1. Identify authority2. Allow authority to impose “truth”

3. Blindly trust authority

How things are :-(

Someone,

somewhere

How things are :-(

Someone,

somewhere

Centralisation & Central Authorities

Single point of controlSingle point of failure

Single bottleneck

The limitation

Authority may be:incompetent (Sony &c. vs. thieves)

compromised (Google/Facebook &c. vs. NSA)biased (Visa/Mastercard/Paypal vs. Wikileaks)

corruptunavailable

unknown

Can’t we do better?

Technology!

The new solution

Avoid relying on authority.Use consensus of peers.

How things should be :-)

How things should be :-)

Basic Premise

“The truth is more common than any one lie”

Liars can try but, ultimately, they’ll be ignored by all others.

Which makes...

A decentralised solution for any sort of chronicling.

Chronicling: Time-series of archivable data

Block chain?

Digital messages (transactions) bundled into:

...Blocks.

Blocks linked in a chain to form chronicle.

The “Block Chain”

The “Genesis” block0

1

2

Proof-of-WorkTimestamp

Proof-of-WorkTimestamp

PoW: A Buttress of waste

“Why your chain and not mine?”

Longest chain is “best”shorter chains are ignored

Non-trivial to make long chains as energy must be wasted (proof-of-work) in order to create blocks.

Chain to State

It’s one thing to have a single chronicle,it’s another to know what it means

What is the language?

Transaction Semantics

...or the meaning of a transaction.

And thus the accumulated meaning of the chronicle.

Bitcoin

Transaction: the transfer of some value so it can only be transferred onwards by using

(signing with) some secret.

Chronicle: The total value accessible by each secret key.

i.e. the account balances

Why form consensus?

Alice starts with $100

At the same time:Alice transfers $100 to Bob

Alice transfers $100 to Charlie

What happens?

The “double-spend” solution

A chronicle that everyone agrees on forces a single order. This is required.

$100 goes to either Bob or Charlie, but never both.

Second transfer ignored as no funds left.

Everyone agrees upon the recipient

The Alts

Attributes altered such as:

Proof-of-Stake: virtual “proof-of-work”Supply: increase, reduce, fixed, random, select

Best: GHOST rather than lengthSpeed: Lower block-time

Where are we going?

Language

StructuredBoolean

Rules

Triv

ial

Am

men

dabl

eG

ener

al

Numeric Discrete

(Less Relevant) (More Relevant)

CRYPTO-CURRENCY

APP-COINS

CRYPTO-FINANCECRYPTO-LAW

ethereum

Formally...

Collective of Non-Localised Singleton Programmable Data-Structures

no authority, no centre, no server

Simile

Internet is to communicationas

Ethereum is to agreements

Another Simile

Ethereum is to Bitcoinas

a smart-phone is to a calculator

Bitcoin & Crypto-currencies

Used blockchain to implement basic clearing house contract without a central server

Ethereum & Crypto-law

Uses blockchain to implement arbitrary social contracts without a central server

Ethereum: State

Like Bitcoin, accounts with balances.Unlike Bitcoin, accounts can be contracts:

code to execute;storage for structured data

Ethereum: Transactions

Like in Bitcoin, transfer funds.

AlsoTransactions have data attached.

If destination omitted, creates a contract.If destination is contract, code gets executed.

Extensible semantics

Bitcoin: single accepted semantic for all data.(ownership of funds)

Ethereum: semantic dependent on contract.

Hacking Society

What does a contract look like?

Code Execution: Virtual Machine

Arbitrary size stackPUSH, POP, SWAP, DUP

Arbitrary temp memory (2256 bytes addressable)

MLOAD, MSTORE

Code stored in virtual ROMCODESIZE, CODECOPY

Virtual Machine

Arithmetic/Logic & CryptoADD, EXP, EQ, AND, LT, BYTE, SHA3 &c

Flow controlJUMP, JUMPI, PC

VM: Environment

Can read message input dataCALLDATALOAD, CALLDATASIZE, CALLDATACOPY

Can halt & give message output dataRETURN, STOP, SUICIDE

VM: Environment

Arbitrary storage (2256 words addressable)ISOLATED FROM OTHER ACCOUNTS

SLOAD, SSTORE

Can create & send messages.CREATE, CALL

VM: Environment

Can query blockchain informationTIMESTAMP, PREVHASH, NUMBER, COINBASE, &c.

Other informationADDRESS, BALANCE, ORIGIN, CALLER

VM

Storage, memory & processing costs ETH

(actually, costs GAS butGAS ⇔ ETH)

LLL: Basics

expression := ( <op-code> [<operand> ...] )<operand> is just expression

0 -> PUSH 0

(mload 0x20) -> PUSH 0x20 MLOAD

LLL: Advanced

variables: (set ‘name <expression>)

(mload x) / (mstore y z): @x / [y] z

(sload x) / (store y z): @@x / [[y]] z

(calldataload x): $x

Simple Currency

[[ (caller) ]] 0x1000000000000(returnlll (when (= (calldatasize) 64) { (set ‘a @@(caller)) (when (>= @a $32) { [[(caller)]] (- @a $32) [[$0]] (+ @@ $0 $32) })}))

LLL: More

variadic arithmetic/logic

macros: (def ‘sqr (x) (* x x)) (sqr 4): (* 4 4)

LLL: Name Registration

(def ‘registrar 0x50441127ea5b9dfd835a9aba4e1dc9c1257b58ca)[0] 'register[32] 'Exchange(call (- (gas) 21) registrar 0 0 64 0 0)

Virtual currencies (Bitcoin)Digital proxy currencies (CFD, ‘Goldcoin’)

Financial instruments (Derivatives, Futures)Insurance & gaming

Registrars (ICANN, Namecoin, land)Reputation systems (Facebook, eBay)

Possible uses?

And eventually...

Trust systems (Verisign)Deeds & ownership

Document revision controlVoting systems

DAOsYour imagination!

The Project

100% Free SoftwareInclusive development, open source code.Official C++, Go, Python implementations.

Unofficial Java & Javascript

Development lead by

Ethereum ÐΞV team:

Jeff WilckeGavin Wood

Vitalik Buterin

& many contributors...

Specifications & Implementations:

White paper (Buterin)Yellow paper (Wood)

C++ (Wood)Go (Wilcke)

Python (Buterin et al)Javascript (Becze)

Java (Mandeleil, Savers)

Crowd Sale

Recently received over 30,000 BTC from sale of the future “crypto-fuel”.

Development underway atgithub.com/ethereum

(Great C++ coders walk this way!)

And Web 3.0?

The decentralised Web

- or -

The Web without any web servers

ethereumFrom there to here, and onwards yonder

Questions?