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Demystifying Blockchains
Henning Diedrich & Vlad Zamfir
Blockchain Workshops  London 2015
Bitcoin and the blockchain
 power
 hype
 reality
Bitcoins innovations
 blockchains
 economic consensus
Projects
 Bitcoin
 Ripple
 Stellar
 Hyperledger
 Ethereum
 Eris
 Tendermint
What is Consensus?
 Consensus protocols are used to make ONE
reliable computer out of many unreliable or
untrusted computers
What is Consensus?
 They are used in real-life applications
 processors
 databases
 flying cars
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
Traditional Consensus Protocols
tc
 Coordinate on changes to the state
 Changes are never reverted
 They just stop if too many nodes go offline
 Blockchains are consensus protocols that
come to consensus through compromise
 Fork-choice rule
What is a blockchain?
BC
Why a blockchain?
 They are available in the event of network
partitions
 Blockchains are more decentralized than
traditional consensus protocols
BC
Maintain a shared, trusted computer even though we dont
trust each other because we know that screwing it up would
cost us a lot of money. - The Joker
What is Economic Consensus?
eeconomic
 Public consensus
 Guarantees correctness
 even for private consensus
 trustless
Maintain a shared, trusted computer even though we dont
trust each other because we know that screwing it up would
cost us a lot of money. - The Joker
Why Economic Consensus?
eeconomic
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
Blockchain projects
 Bitcoin
 Ripple
 Stellar
 Hyperledger
 Ethereum
 Eris
 Tendermint
Bitcoin disintermediate banks
& currencies
Zerocash
anonymous
Bitcoin
Ripple
replace SWIFT
Stellar
bank the unbanked
Hyperledger
inter-bank clearing
Ethereum
public
smart contract
platform
public
smart contract
platform
Tendermint
Eris
private
smart contracts
platform stack
Core Design
 private
 public
 traditional consensus protocol
 decentralized blockchain
 transaction network
 virtual machine
Bitcoin disintermediate banks & currencies
public, decentralized blockchain
+ virtual machine
replace SWIFT
Ripple
private transaction network
with built-in currency conversions
bank the unbanked
Stellar
private transaction network
with built-in currency conversions
Hyperledger
inter-bank clearing
private consensus protocol
Ethereum
public
smart contract
platform
public, decentralized blockchain
+ virtual machine
Tendermint
public, decentralized blockchain
+ virtual machine
public
smart contract
platform
Eris
private
smart contracts
platform stack
private consensus
+ virtual machine
Smart Contracts
 Virtual machine ...
  with transaction capacity (token)
 Oracle input from outside world
Smart Contracts
Bitcoin Ethereum Tendermint Eris
Smart Contracts
Bitcoin VM Ethereum Virtual Machine
(EVM)
Bitcoin Ethereum Tendermint Eris
Maintain a shared,
trusted computer
even though we
dont trust each
other because we know that screwing
it up would cost us a lot of money.
What is Economic Consensus?
eeconomic
Bitcoin disintermediate banks & currencies
public, decentralized blockchain
+ virtual machine
eeconomic
BC
non-economic
e
Ripple
replace SWIFT
private transaction network
with built-in currency conversions
bank the unbanked
e
Stellar
private transaction network
with built-in currency conversions
non-economic
enon-economic
inter-bank clearing
private consensus protocol
tc
e
Hyperledger
non-economic
public
smart contract
platform
Ethereum
public, decentralized blockchain
+ virtual machine
eeconomic
BC
Tendermint
public
smart contract
platform
public, decentralized blockchain
+ virtual machine
tc
eeconomic
Eris
private
smart contracts
platform stack
private consensus
+ virtual machine
enon-economic
tc
enon-economic
Thank You!
Questions!
Credits
Roof top - 息 Can Stock Photo Inc. / solarseven
Handshake - 息 Can Stock Photo Inc. / a_papantoniou
Roman - 息 Can Stock Photo Inc. / Nejron
Chain ball - 息 Can Stock Photo Inc. / 3quarks
Joker - 息 Can Stock Photo Inc. / sad
Ring - 息 Can Stock Photo Inc. / Marisabell
Iron claw - 息 Can Stock Photo Inc. / andreykuzmin
Swordman - 息 Can Stock Photo Inc. / prometeus
Monk  息 Can Stock Photo Inc. / FotoMaximum
Colour man - 息 Can Stock Photo Inc. / alphaspirit
Hero girl - 息 Can Stock Photo Inc. / Choreograph
White boy - 息 Can Stock Photo Inc. / prometeus
Sword giver - 息 Can Stock Photo Inc. / prometeus
Blue android - 息 Can Stock Photo Inc. / leafsomen
Blue girl - 息 Can Stock Photo Inc. / FotoMaximum
Green robot - 息 Can Stock Photo Inc. / leafsomen

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