Blockchains provide a decentralized and trustless platform for computing by creating a shared global state through a Byzantine Fault Tolerant system of transaction verification. This allows for applications like cryptocurrencies and smart contracts that provide guarantees around atomicity, immutability, and permanent data storage. While early blockchains were limited in their capabilities, newer platforms like Ethereum enable multi-user accounts, object-oriented programming and interoperability to build a more general world computer. Blockchains reduce the need for trust between parties by diffusing it across the network.

1. Blockchains:
What and Why
Dr. Gavin Wood
co-founder, ethereum project
founder, ethcore limited
@gavofyork

2. Take a step back

3. Important Things to Forget
Coin
Crypto
Currency
Bit
ChainBlock
Hash
Consensus
Fork
MinerSign
ASIC
Curve

4. What is the Blockchain?

5. A Blockchain is...
A Byzantine-Fault-Tolerant decentralised
singleton fixed-function state-transition
system

7. It’s a type of Computing Machine
Slow
Code runs 5-100x slower that natively compiled
Expensive to use
Basic computation, memory and storage costs are ~1950s levels
Not always immediately decisive
(Trans-)Actions can sometimes be reorganised

8. Sounds. Awesome.

9. Actually, it is.
A Shared Singleton
One single computer among many
Cannot Break, Shut down or be Corrupted
Resistant to attack or coercion
Ubiquitous
No special or costly hardware required for access
Verifiable & Auditable
All transactions recorded, archived and replayable. Always.

10. So, Bitcoin?

11. And Ethereum?

12. Natively Multi-User
Has as many accounts as is needed
Natively Object-Oriented
Encapsulation enforced in “virtual silicon”
Accessible
Wherever there’s Javascript, there’s Ethereum

13. And Smart Contracts?

14. So, Bitcoin would be...

15. Guarantees for Smart Contracts
Atomicity
Entire operation runs or nothing does
Synchrony
No two operations can interfere with each other
Provenance
All messages (method calls) can be inspected to determine caller address

16. Guarantees
Permanence
Object’s data are permanent
Immortality
Object can never be externally deleted - can only voluntarily commit suicide
Immutability
Object’s code can never be changed

17. 1995

18. 2015

19. Mauve?
Types of Blockchain

20. Permissioned vs Permissionless
Faster
Managed upkeep
Private membership
Trusted
Legal
Slower
Public ownership
Open & transparent
Trust-free
Allegal

21. PoW vs PoS vs PoA
Slower
Wasteful
Hardware
No-finality
Trust-free
Proven
Costly
Fastest
Efficient
Software
Finality
Trust-bound
Safe
Free
Faster
Efficient
Software
Finality (Possible)
Trust-free
Unproven
Less costly

22. Why?

23. Compared to connection-poor siloes
Innovation Turbocharger

24. Walled Gardens
Interoperability Difficult
Reliability, standards, trust, security collude to make it a nightmare
Increased Barriers
For integrating multi-party, multi-domain systems
Cumbersome
Servers are expensive to set up and maintain;
Blockchain always-on, always ready

25. Not to mention Security
Auditability
All results are readily auditable from their inputs
Security
Fewer servers and databases to hack
Authenticity
All interactions are cryptographically signed:
Unauthorised Interactions are Impossible

26. A bridge across trust boundaries
Diffuses the Trust
Problem

27. Blockchain
Platform for Reduced-trust Computing
for
identity management
smart contracts
interoperable infrastructure
permissions management
auditability

28. Why Not?

29. Problems
Privacy
Everyone validates everything - everyone sees everything
Scalability
Everyone processes everything - in order
Integration & Infrastructure
Not yet baked

30. Blockchain:
What and Why
Dr. Gavin Wood
@gavofyork
Questions?