What is a blockchain? How do the existing contenders compare? Listing purpose and features of Bitcoin, Zerocash, Ripple, Stellar, Hyperledger, Ethereum, Tendermint and Eris on that basis.
Talk at the 3rd Blockchain Workshop, London 2015. By one of the pre-eminent blockchain researchers, Vlad Zamfir.
5. What is Consensus?
● Consensus protocols are used to make ONE
reliable computer out of many unreliable or
untrusted computers
6. What is Consensus?
● They are used in real-life applications
○ processors
○ databases
○ flying cars
7. Traditional Consensus Protocols
● Clients in these protocols only change their
state when a supermajority approves of the
changes, or elects a leader who proposes
the changes
tc
8. Traditional Consensus Protocols
tc
● Coordinate on changes to the state
● Changes are never reverted
● They “just stop” if too many nodes go offline
9. ● Blockchains are consensus protocols that
come to consensus through compromise
● “Fork-choice rule”
What is a blockchain?
BC
10. Why a blockchain?
● They are available in the event of network
partitions
● Blockchains are more decentralized than
traditional consensus protocols
BC
11. “Maintain a shared, trusted computer even though we don’t
trust each other because we know that screwing it up would
cost us a lot of money.” - The Joker
What is Economic Consensus?
eeconomic
12. ● Public consensus
● Guarantees correctness
○ even for private consensus
○ “trustless”
“Maintain a shared, trusted computer even though we don’t
trust each other because we know that screwing it up would
cost us a lot of money.” - The Joker
Why Economic Consensus?
eeconomic
13. How do we make faults expensive?
● Proof-of-work
○ Make changing the state expensive
● Proof-of-stake
○ Use security deposits to punish nodes who propose
competing updates to the consensus
eeconomic
34. “Maintain a shared,
trusted computer
even though we
don’t trust each
other because we know that screwing
it up would cost us a lot of money.”
What is Economic Consensus?
eeconomic
