Block ckch chain in the Limelight Leila Bahri Researcher - - PowerPoint PPT Presentation

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Block ckch chain in the Limelight Leila Bahri Researcher - - PowerPoint PPT Presentation

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Block ckch chain in the Limelight Leila Bahri Researcher lbahri@kth.se Oct. 15, 2019, Castor Days Stockholm Bl Blockchain, , an early-st stage te technology that at enables the de decentralized, , se secure storage and tr tran

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Block ckch chain in the Limelight

Leila Bahri

Researcher lbahri@kth.se

  • Oct. 15, 2019, Castor Days

Stockholm

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“Bl Blockchain, , an early-st stage te technology that at enables the de decentralized, , se secure storage and tr tran ansfer er of in informatio tion, has as th the e po potential to to be a po powerful ul tool fo for tr trac ackin ing an and tr tran ansac actio tions th that t can an mi minimi mize friction, , red educe e co corruption, , in increas ease e tr trust an and em empower er user ers.” .”

World Economic Forum

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“H “How can we ensu sure that ev everyone – fr from th the most t ma marginalized ed memb member ers o

  • f

soc society to to the most st powerful – bene benefits from bl block ckcha chain’ n’s tr tran ansformativ tive potential tial?” ?”

Wo World Economic Forum

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But What is Block ckch chain?

  • Bitcoin
  • Cryptocurrency
  • Public ledger
  • Mining
  • Proof-of-Work
  • Energy consumption
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With Bitcoin, there are 10 types of countries in the world, …

Those that consume less electricity than Bitcoin Mining Those that consume more electricity than Bitcoin Mining

Bitcoin uses *more* energy than Denmark does1

1 https://news.abs-cbn.com/business/11/06/18/mining-bitcoin-uses-more-energy-than-denmark-study

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Wh Why do does Mi Mini ning ng (Pr Proof-of

  • f-Wo

Work) ) co consume tha that much ch en ener ergy gy?

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Wh Why is is min inin ing ev ever needed needed?

To Create / Find new Bitcoins!

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Wh Why is is min inin ing ev ever needed needed?

To Create / Find new Bitcoins!

There is more to mining than creating Bitcoins à Reaching consensus

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Th There is is mor more to to mining th than an cr creating Bi Bitcoi

  • ins…
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Th There is is mor more to to mining th than an cr creating Bi Bitcoi

  • ins…

Ledger collaboratively managed by the open public

Issue: How to agree on the state of the ledger among the members of the P2P network

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Call this a Block Chain (Chain of Blocks)

Change presentation

A da data st structure re / d / data r representation

  • n po

point … …

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Th There is is mor more to to mining th than an cr creating Bi Bitcoi

  • ins…

When it is time to add new transactions:

  • Who will be eligible to add the next transaction (or

block)?

  • How to agree on the new state of the

ledger/Blockchain?

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Th There is is mor more to to mining th than an cr creating Bi Bitcoi

  • ins…

When it is time to add new transactions:

  • Who will be eligible to add the next block?
  • How to agree on the new state of the Blockchain?

Joining the network

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Th There is is mor more to to mining th than an cr creating Bi Bitcoi

  • ins…

Joining the network Forging identities Leaving the network

When it is time to add new transactions:

  • Who will be eligible to add the next block?
  • How to agree on the new state of the Blockchain?
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Th There is is mor more to to mining th than an cr creating Bi Bitcoi

  • ins…

Joining the network Forging identities Leaving the network

Issue: How to elect the next block “miner” in an open uncontrolled environment with NO TRUST between the members? It is not about finding “bitGold”, it is all about “consensus”!

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Mi Mining ( (Po PoW) ) - Con Consensus wi with NO TR TRUST

Collect broadcasted transactions Race to solve a puzzle Prove Found solution to the network Add winner’s transactions to the ledger I won?

Yes J No L

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Mi Mining ( (Po PoW) ) - Con Consensus wi with NO TR TRUST

Roots:

  • Playing little tricks with Cryptographic Hash Functions

Advantages:

  • One CPU one vote à Cannot forge virtual peers
  • Secure provable consensus mechanism
  • Simple and easy for verification

Disadvantage

  • Burns TOO MUCH energy
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Wha What is is a a Blo lockchain ain

A ledger of timestamped transactions, securely chained in a time-based

  • rdered manner (from old to new), that is created and maintained by a

peer-to-peer system using a consensus mechanism that provides security guarantees against identity forging.

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Pos

  • ssible

Us Uses es of

  • f

Bl Bloc

  • ckchain

Adapted from: https://teks.co.in/site/blog/blockchain-beyond-financial-services-13-applications-use-cases/

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An Any alt alter ernativ tives es to Po PoW?

  • Proof-of-Something (for real decentralized systems)
  • Proof-of-Stake
  • Proof-of-Activity
  • Proof-of-Useful-Work
  • Proof-of-Trust1
  • Permissioned Blockchain with traditional consensus algorithms
  • Decentralization is put at stake (?)

1 “Trust Mends Blockchain – Living uo to Expectation”, L. Bahri & Sarunas Girdzijauskas. Published at ICDCS’2019

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Th Thank yo you fo for yo your tr trust t J

lbahri@kth.se