Blockchains:What and Why

Dr. Gavin Woodco-founder, ethereum project

founder, ethcore limited

@gavofyork

Take a step back

Important Things to Forget

Coin

Crypto

Currency

Bit

ChainBlockHash

Consensus

Fork

MinerSign

ASIC

Curve

What is the Blockchain?

A Blockchain is...

A Byzantine-Fault-Tolerant decentralised singleton fixed-function state-transition

system

It’s a type of Computing Machine

SlowCode runs 5-100x slower that natively compiled

Expensive to useBasic computation, memory and storage costs are ~1950s levels

Not always immediately decisive(Trans-)Actions can sometimes be reorganised

Sounds. Awesome.

Actually, it is.

A Shared SingletonOne single computer among many

Cannot Break, Shut down or be CorruptedResistant to attack or coercion

UbiquitousNo special or costly hardware required for access

Verifiable & AuditableAll transactions recorded, archived and replayable. Always.

So, Bitcoin?

And Ethereum?

Natively Multi-UserHas as many accounts as is needed

Natively Object-OrientedEncapsulation enforced in “virtual silicon”

AccessibleWherever there’s Javascript, there’s Ethereum

And Smart Contracts?

So, Bitcoin would be...

Guarantees for Smart Contracts

AtomicityEntire operation runs or nothing does

SynchronyNo two operations can interfere with each other

ProvenanceAll messages (method calls) can be inspected to determine caller address

Guarantees

PermanenceObject’s data are permanent

ImmortalityObject can never be externally deleted - can only voluntarily commit suicide

ImmutabilityObject’s code can never be changed

1995

2015

Mauve?

Types of Blockchain

Permissioned vs Permissionless

FasterManaged upkeep

Private membershipTrusted

Legal

SlowerPublic ownershipOpen & transparentTrust-freeAllegal

PoW vs PoS vs PoA

SlowerWastefulHardwareNo-finalityTrust-freeProvenCostly

FastestEfficient

SoftwareFinality

Trust-boundSafeFree

FasterEfficientSoftware

Finality (Possible)

Trust-freeUnprovenLess costly

Why?

Compared to connection-poor siloes

Innovation Turbocharger

Walled Gardens

Interoperability DifficultReliability, standards, trust, security collude to make it a nightmare

Increased BarriersFor integrating multi-party, multi-domain systems

CumbersomeServers are expensive to set up and maintain;

Blockchain always-on, always ready

Not to mention Security

AuditabilityAll results are readily auditable from their inputs

SecurityFewer servers and databases to hack

AuthenticityAll interactions are cryptographically signed:

Unauthorised Interactions are Impossible

A bridge across trust boundaries

Diffuses the Trust Problem

Blockchain

Platform for Reduced-trust Computingfor

identity managementsmart contracts

interoperable infrastructurepermissions management

auditability

Why Not?

Problems

PrivacyEveryone validates everything - everyone sees everything

ScalabilityEveryone processes everything - in order

Integration & InfrastructureNot yet baked

Blockchain:What and Why

Dr. Gavin Wood@gavofyork

Questions?