The structure of technical Sections of this course is based on Drescher (2017), which is an excellent source for non-technical introduction to blockchains. The other main sources are Bashir (2018), Omote and Yano (2020), Trautman & Molesky (2019) and Zheng et al. (2016, 2018). This summary closes the technical part, going through all the previous technical Sections in a compressed format.
Chapters 1 and 2 dealt with different networks and basic terminology, along with a definition of the blockchain. We limited ourselves to a discussion on peer-to-peer and centralized networks, with a brief look also on mixing these two types. The basic vocabulary defined included ledger, algorithm, ordered and connected blocks and cryptographic and security technologies. The definition of the blockchain was given, namely stating blockchain being a software in a distributed peer-to-peer network which utilizes a ledger as a tool to safely store and transmit data between the nodes of the network. This data is stored, using different algorithms, into blocks which are ordered and connected and safeguarded using cryptography. With hindsight, we can add that blockchains can also be employed in a centralized network.
Chapters 3 and 4 dealt with ownership, cryptography, and digital signatures. The ownership was defined as a proven record of acquisition of a certain object, with enough evidence to support one’s claim. This definition was then shown in the case of blockchain, with the private key of asymmetric cryptography working as a proof of ownership. The digital signature is created for every transaction and it verifies the data, as well as makes the recipients aware of a possible fraud.
Chapters 5 and 6 discussed on the transaction data transmitted in a blockchain network. First, a simplified illustration of a transaction data type was given, while defining all the parts. Then adding new transaction data to a blockchain was discussed, with specific target of showing, how the transaction data transmitted in the network is rendered immutable. The communication between peers of the network was also addressed, as it is paramount that all the network nodes work together to keep the transaction data up to date. Here special emphasis was given for blockchains working similarly to Bitcoin.
Chapter 7 viewed the transaction history of a blockchain more closely. This Chapter dealt with the forking nature of the blockchain transactions, and how the “blocktree” can be controlled in a secure fashion. The main finding was that the blockchain transactions are not one hundred percent sure to be added to the blockchain straight away and some may be dismissed for a comparably long period of time, if they end up in a branch which is cut off from the main chain. However, this functionality guarantees that blockchain given time always has a transaction history that is accepted by consensus of the peers in the network.
Chapter 8 gave a short summary of the discussion so far, while Chapter 9 introduced the possible future developments of the blockchain. The main parts of any blockchain were identified in the latter, while the former discussed the possibility of more centralized blockchain networks being used in the future.
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