PX 2018: Blockchain - Midterm Presentation
Johannes Schneider, Julian Weise
Software Architecture Group
Hasso Plattner Institute
University of Potsdam, Germany
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## Blockchain
"Decentralized, chronological updated database with a network based consensus mechanism for permanent confirmation of ownership."
Prof. Dr. Andreas Mitschele
- 1991: timestamping
- proof creation date of scientific documents
- 1992: introducing merkle trees
- 2008: append-only ledger
- first working implementation in Bitcoin
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## Blockchain as data structure
- Transactions
- stores arbitrary data and their occurrence
- Blocks
- contains a strictly ordered set of transactions
- Chain of blocks
- connects several blocks using hashing algorithms
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## Attributes of blockchains
- append-only
- strictly ordered
- chronological sequence unambiguously
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## Distributed blockchain
- decentralized ledger
- replicated data on every node in the p2p-network
- network-defined consensus for data validation
- every node is enabled to independently validate transactions
- distributed trust
- there is no central authority → every node is able to determine its own truth
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## Examples
- Bitcoin
- presentation follows along Bitcoin architecture due to historical background
- other crypto currencies
- Ethereum, FileCoin, BlockStack
- other usages of blockchain technology
- data ownership / access rights, voting, naming systems
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## Blockchain hype technology!?
- hardly any usecases with the need of blockchain technology (so far)
- high consumption of energy (e.g.: proof of work in Bitcoin)
- trust based on the assumption that the major part of the network behaves honestly
- redundancy in many cases not necessary to fulfill requirements → waste of storage