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

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 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

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

But What is Block ckch chain? • Bitcoin • Cryptocurrency • Public ledger • Mining • Proof-of-Work • Energy consumption

With Bitcoin, there are 10 types of countries in the world, … Bitcoin uses * more * energy than Denmark does 1 Those that consume less electricity than Bitcoin Mining Those that consume more electricity than Bitcoin Mining 1 https://news.abs-cbn.com/business/11/06/18/mining-bitcoin-uses-more-energy-than-denmark-study

Wh Why do does Mi Mini ning ng (Pr Proof-of of-Wo Work) ) co consume tha that much ch en ener ergy gy?

Wh Why is is min inin ing ev ever needed needed? To Create / Find new Bitcoins!

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

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

Th There is is mor more to to mining th than an cr creating Bi Bitcoi oins… Ledger collaboratively managed by the open public Issue: How to agree on the state of the ledger among the members of the P2P network

A da data st structure re / d / data r representation on po point … … Change presentation Call this a Block Chain (Chain of Blocks)

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

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

Th There is is mor more to to mining th than an cr creating Bi Bitcoi oins… When it is time to add new transactions: Leaving the network Who will be eligible to add the next block? • How to agree on the new state of the Blockchain? • Forging identities Joining the network

Th There is is mor more to to mining th than an cr creating Bi Bitcoi oins… Leaving the Issue: How to elect the next block network “miner” in an open uncontrolled environment with NO TRUST It is not about finding “bitGold”, it is between the members? all about “consensus”! Forging identities Joining the network

Mi Mining ( (Po PoW) ) - Con Consensus wi with NO TR TRUST Collect broadcasted transactions Add winner’s Race to solve No L transactions I won? a puzzle to the ledger Yes J Prove Found solution to the network

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

Wha What is is a a Blo lockchain ain A ledger of timestamped transactions, securely chained in a time-based ordered 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.

Pos ossible Us Uses es of of Bl Bloc ockchain Adapted from: https://teks.co.in/site/blog/blockchain-beyond-financial-services-13-applications-use-cases/

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-Trust 1 • 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

Th Thank yo you fo for yo your tr trust t J lbahri@kth.se