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TDC SP 2019 - Trilha Blochchain - Algoritmos de...

TDC SP 2019 - Trilha Blochchain - Algoritmos de Consenso

Blockchain - Consensus Algorithms presentation by Leonardo Piedade.

Leonardo

July 16, 2019
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  1. 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. [email protected]
  2. 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
  3. 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
  4. Globalcode – Open4education 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!
  5. Globalcode – Open4education “It is a process of agreement between

    distrusting nodes on a final state of data.” Consensus
  6. Globalcode – Open4education 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/
  7. Globalcode – Open4education 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
  8. Globalcode – Open4education Fault Tolerance “The consensus algorithm should be

    able to run in the presence of faulty or malicious nodes.”
  9. Globalcode – Open4education Classical Consensus “Every participant gets one vote”

    Examples: Paxos, Practical Byzantine Fault Tolerance (PBFT)
  10. 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
  11. Globalcode – Open4education 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
  12. 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
  13. 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
  14. Globalcode – Open4education Practical Byzantine Fault Tolerance (PBFT) - 1999

    http://pmg.csail.mit.edu/papers/osdi99.pdf Examples: Corda*, Hyperledger*, Neo*, Quorum* Closed networks Leader-based Full peering
  15. 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