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![Ethereum-style constraints
from = msg.sender
fromvalue = contract.storage[from]
to = msg.data[0]
value = msg.data[1]
if fromvalue >= value:
contract.storage[from] -= value
contract.storage[to] += value
return(1)
else:
return(0)](https://image.slidesharecdn.com/understandingprivateblockchains-160616123633/85/Understanding-private-blockchains-11-320.jpg)
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Understanding private blockchains
This document discusses private blockchains and how they differ from public blockchains. It explains that private blockchains are permissioned shared databases that use blockchain technology like cryptography and consensus algorithms to provide trust between entities that have limited trust. While they don't have the same properties as public blockchains like immutability and anonymity, private blockchains can enable use cases like financial settlement, provenance tracking, and interorganizational record keeping where a centralized database is not ideal due to lack of trust or need for disintermediation. The document addresses criticisms of private blockchains and blockchain technology in general. It also introduces the MultiChain platform for deploying private blockchains.
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Understanding private blockchains
- 1. Understanding private blockchains Dr GideonGreenspan, Founder and CEO
- 2. A brief historyof blockchains 2009 Bitcoin 2011—2013 Altcoins 2015— Many private blockchains http://corporate.comcast.com/comcast-voices/comcast-sponsors-internet-measurement-hackathon
- 3. Public blockchains inenterprises? • Low capacity • Poor governance • Unknown costs • Anonymous miners • Cryptocurrencies • Writable by all • Visible to all • One bloated ledger
- 4. Blockchains for enterprises • Private shared database • Byzantine fault tolerance • Control of capacity + cost • Designated “miners” • No cryptocurrency • Collective admin • Blockchain as tool not ideology
- 5. Tomato 1 This isjust a shared database!
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- 8. Peer-to-peer shared databases Node Node Node NodeTransaction Block Blockchain Consensuscreated by validator nodes
- 9. Peer-to-peer DB requirements • Atomic transactions – Self-contained “packets” • Peer-to-peer ⇒ origin unknown – Transactions digitally signed – All data tagged by public key/s • Shared write ⇒ transaction constraints – Bitcoin vs Ethereum style • Consensus mechanism
- 10. Signed by Bob Signedby Alice Alice £10 Bob $15 Alice $15 Bob £10 Bitcoin-style constraints Metadata: b469dc12a0746…
- 11. Ethereum-style constraints from =msg.sender fromvalue = contract.storage[from] to = msg.data[0] value = msg.data[1] if fromvalue >= value: contract.storage[from] -= value contract.storage[to] += value return(1) else: return(0)
- 12. A new typeof shared database
- 13. Tomato 2 This isnot immutable!
- 14. “Mining” in privatechains • All blocks signed by miner • Only permitted miners ü No impersonation attacks • Mining diversity constraint ü Proof of work not required
- 15. On immutability • Publicblockchains – Secured by hashing power – Mutable by 51% of hashrate – Threat: someone rich (e.g. a government) • Private blockchains – Secured by distributed consensus – Mutable by ≥51% of validators – Threat: validator collusion
- 16. Tomato 3 This isnot a blockchain!
- 17. Public vs privateblockchains Different Same Permissions model Peer-to-peer architecture Transaction censorship Byzantine fault tolerance Native cryptocurrency Public key cryptography “The blockchain” Transaction constraints Proof-of-work consensus Consensus chain of blocks
- 18. Public vs privateblockchains Different Same Permissions model Peer-to-peer architecture Transaction censorship Byzantine fault tolerance Native cryptocurrency Public key cryptography “The blockchain” Transaction constraints Proof-of-work consensus Consensus chain of blocks
- 19. Philosophical Investigations “the meaning ofa word is its use in the language” — LW
- 20. Tomato 4 This has nouses!
- 21. What are blockchainsfor? • Old problem: – Shared database (or ledger) – Multiple writers – Limited trust • Old solution: – Centralized database at intermediary • New possibility: – Use a (private) blockchain
- 22. Blockchains vs centralizedDBs Advantages Disadvantages Disintermediation Confidentiality Robustness Performance
- 23. Post-trade settlement? • Interbankblockchain • Issue any asset on chain • Rapid settlement • Delivery versus payment • No need for reconciliation • Regulatory transparency
- 24. Post-trade settlement? • Interbankblockchain • Issue any asset on chain • Rapid settlement • Delivery versus payment • No need for reconciliation • Regulatory transparency Confidentiality
- 25. Strong blockchain usecases • Lightweight financial systems • Provenance tracking • Interorganizational record keeping – Multiparty data aggregation
- 26. Lightweight finance • Anyasset can be tokenized on blockchain – Tokens issued by trusted entity/s – Token confers right of redemption • Disintermediates centralized control – More secure and cheaper • Confidentiality limits applications – Small financial trading circles – Gift cards, loyalty points
- 27. Provenance tracking • Digitalcertificate of authenticity – Physical transfer ⇒ token transfer – Verifiable chain of custody • Disintermediates risk of fraud – Collusion cannot corrupt • Confidentiality via multiple addresses – Fewer transactions between competitors – Regulation can still be a concern
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- 29. Interorganizational records • Collectivelyrecord and notarize – Communications or transactions – Digital signatures + immutability • Infrastructure solution for large groups • Disintermediates external party – Cheaper and simpler • Confidentiality easily addressed – Encryption or hashing
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- 32. New? Bitcoin transactionmodel http://qiita.com/yanagisawa-kentaro/items/503dfce3762e3b1237c9
- 33. New? Compact stateproofs https://blog.ethereum.org/2015/11/15/merkling-in-ethereum/
- 34. New: Awareness +Productization
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- 38. Tomato 7 This isall vaporware!
- 39. MultiChain blockchain platform • Off-the-shelf private blockchains ü Easy to configure and deploy • Permission management ü Private and tightly controlled • Native asset support ü Tracked at network level • Extendable via metadata ü Up to 8MB arbitrary data per transaction
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- 41. Questions? Visit www.multichain.com for: MultiChaindownload Getting started guide Developer docs and forum Popular private blockchain blog