Globalcode – Open4education
Speaker
Leonardo Piedade
- 15+ years programming
- 12+ years developing using Java
- BS Degree in Computer Science
- Web, Integration Systems, Backend, Distributed
Systems and Blockchain Platforms.
leoabrahao@gmail.com
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Globalcode – Open4education
The Trust Machine
“It is the first, full consensus distributed
ledger mankind has ever seen”
– Mastering Blockchain about Bitcoin
https://www.economist.com/leaders/2015/10/31/the-trust-machine
Globalcode – Open4education
Blockchain Principles
Distributed Ledger
Technology
Data, assets, records, etc...
Immutable transactions
Everybody has a copy
P2P Network
Partial or Fully Distributed
Consensus
Untrusted Nodes
Economic Model
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Network Models
Central Intermediary Competing Intermediaries No Intermediary
(aka P2P)
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“More precisely it is a decentralized
distributed system”
– Bitcoin
In The Crypto World…
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CAP Theorem
“Consistency is sacrificed in favor of
availability and partition tolerance.
But consistency is achieved over
time” – Mastering Blockchain
https://towardsdatascience.com/cap-theorem-and-distributed-database-management-systems-5c2be977950e
ONLY PICK 2 OF THE 3!
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Double Spending
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“consensus algorithms exist to
prevent double spending.”
In The Crypto World…
Globalcode – Open4education
“It is a process of agreement between
distrusting nodes on a final state of
data.”
Consensus
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The Two Generals Problem - 1975
https://www.youtube.com/watch?v=s8Wbt0b8bwY
“Proved to be
unsolved”
https://mwhittaker.github.io/blog/two_generals_and_time_machines/
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The Byzantine Generals Problem - 1982
https://people.eecs.berkeley.edu/~luca/cs174/byzantine.pdf
“It can reach consensus
as long as 2/3 are honest”
- Lamport
https://www.youtube.com/watch?v=dfsRQyYXOsQ
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Fault Tolerance
“The consensus algorithm should be
able to run in the presence of faulty or
malicious nodes.”
Globalcode – Open4education
Classical Consensus
Requires a Closed Network
https://www.imdb.com/title/tt3531824
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Classical Consensus
Requires a Closed Network
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Globalcode – Open4education
Proof of Work (PoW) - 2009
“Proof-of-work is essentially
one-CPU-one-vote”
- Bitcoin whitepaper
Examples:
Bitcoin(*), Ethereum, Dogecoin, Litecoin, Zcash,
Monero, Dash, Primecoin, Verge, Tether
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Globalcode – Open4education
Proof of Work (PoW)
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Proof of Work (PoW)
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Proof of Work (PoW)
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Attacks
“As long as a majority of CPU power is
controlled by nodes that are not
cooperating to attack the network, they'll
generate the longest chain and outpace
attackers.” – Bitcoin whitepaper
https://bitcoin.org/bitcoin.pdf
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51% Attack or Double-Spend Attack
https://medium.com/coinmonks/what-is-a-51-attack-or-double-spend-attack-aa108db63474
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51% Attack or Double-Spend Attack
https://medium.com/coinmonks/what-is-a-51-attack-or-double-spend-attack-aa108db63474
Globalcode – Open4education
Proof of Stake (PoS)
Examples:
Cardano (Ouroboros), Nxt,
Blackcoin, Peercoin
“Everyone gets to vote
proportional to their wealth”
https://www.youtube.com/watch?v=psKDXvXdr7k
Randomized Block Selection
Coin Age Selection
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Globalcode – Open4education
Delegated Proof of Stake (DPoS) – 2014
Examples:
EOS, BitShares, Steem, Lisk, Ark
Digital Democracy
Votes are proportional to the currencies
Faster alternative
Delegates vs Network Speed
https://www.youtube.com/watch?v=OVKAOwzAwHI
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“Don't do it, if you can avoid it.”
Public Networks?
Globalcode – Open4education
Go further
Proof of Activity
Proof of Authority
Proof of Burn
Proof of Capacity/Space
Proof of Deposit
Proof of Elapsed Time
Proof of Importance
Proof of Storage
Delayed Proof of Work
PAXOS
RAFT
Tangle
FBA
Casper FFG
Casper CBC
Hashgraph