I declare that this thesis has been done by me under the supervision of Md ZahidHasan, Assistant Professor, Department of CSE, Daffodil International University. Department of Computer Science and Engineering Faculty of Information Science and Technology Daffodil International University. We would like to thank our esteemed teacher and project supervisor Md ZahidHasan, Assistant Professor, Department of CSE, Daffodil International University for his endless patience, scholarly guidance, constant encouragement, constant and energetic supervision, constructive criticism, valuable advice , the reading of many inferior people. their drafting and correction at all stages made the completion of this project possible.
Finally, we would like to thank our entire course at Daffodil International University who participated in this discussion while completing the course. This thesis is on the topic "Survey on Blockchain and its Application Possibilities". Blockchain proved its potential with the introduction of Bitcoin, the modern cryptocurrency network. Blockchain technology has worked flawlessly over the years and is successfully used in both financial and non-financial world applications.
The aforementioned examples can prove that the current world is relying on a third party for the security and privacy of digital assets. It facilitates distributed consensus for any type of online transaction including digital assets, payments can be verified. When the default condition of a smart contract becomes true among the participating candidates, then the contract agreement is automatically executed, such as making payments or transactions to a specific entity according to contract information.
In addition, smart contract implementation has become simple and IoT devices are much smarter than in the last decade.
Objectives
Report Layout
LITERATURE REVIEW
- Introduction
- Related Works
- Proof of Work (PoW)
- Proof of Stake (PoS)
- Scalability
- Anonymity
- Smart Contract
- Hawk Model – Privacy Preserving Smart Contract
- Blockchain and IoT Powered by Smart Contract
- Music Industry
- Selfish Mining
- Attacks on Blockchain
- Scope of Problems
- Research Challenges
But any individual entity can participate in an open, multi-agency network and try to influence the network in its favor. If this is the case, this can be resolved by checking the next block and so on. To become a validator, each node must deposit a reward point or currency as a stake into the network.
Getting the chance to be chosen as a validator of the network is directly proportional to its staked amount. So if miner A staked 100 reward points and miner B staked 1000, miner B has 10 times more chances to be chosen as a validator by the network. So when the validator signs the block as a valid one and the new block is added in the chain, the validator gets reward points from the network associated with that transaction.
If any other node or network can detect fraud or an invalid block in the chain, the reward point and staked balance will be deducted as a penalty. Moreover, getting 51% of the market capitalization is not possible at all, as it is quite a large number. Further, to avoid fraudulent actions, the network will hold the reward point for a certain period of time as it wants to verify the actions of the validator for that period.
But in NG, the leader block creates the microblock as fast as possible according to the network bandwidth. The contract is thus distributed among all the participants when it is released in the chain. If a user somehow manages to write a non-deterministic contract, he will not be able to implement it in the network.
Smart contracts are immutable, so it is not possible to change the criteria and output clauses after a successful deployment. After a while, when they have grown a long enough chain, they reveal the entire chain to the network. There will be a strict time limit and new blocks must be announced to the network within this time frame.
The current solution to stop double usage (10 minute validation break) is not a good implementation as it affects network latency. Although a smart contract provides many options, it is possible to attack the network using this technique if it is not carefully developed.
ARCHITECTURE OF BLOCKCHAIN
Short History of Bitcoin
Blockchain Network .1 Architecture
- Blocks
- Types of Blocks
- Chain
- Digital Signature
- Transactions
- How Blockchain Works
- What is Mining?
Each block can be represented as a node and each holds a local copy of the ledger. After creating a new block, the newly created block will be added to the end of the chain. Anyone can join this network to participate in the process without any permission as it is publicly open.
Bitcoin uses cryptographic proof which is protected through a digital signature, sent to the receiver's "public key" and digitally signed using the sender's "private key". To spend money, the owner of the cryptocurrency must prove his ownership of the "private key". The entity receiving the digital currency then verifies the digital signature, which signifies ownership of the corresponding "private key", using the sender's "public key" in the corresponding transaction.
Each transaction is broadcast to every node in the Bitcoin network and then recorded in a public ledger after verification. Spender has sufficient cryptocurrency in his account by checking each transaction against the user's account or "public key" recorded in the ledger. The transactions do not come in the order in which they are generated, and therefore there is a need for a system that ensures that double consumption of the cryptocurrency does not occur.
These blocks are linked together as a chain in a proper linear order, with each block containing the hash of the previous block. You can't rely on the order, because blocks in a different phase of the entire network can arrive in a different order. This is solved by introducing a mathematical puzzle: each block is accepted into the Blockchain if it contains an answer to a very special mathematical problem.
This mathematical puzzle is not trivial to solve and the complexity of the problem can be adjusted so that it takes an average of ten minutes for a node in the Bitcoin network to make a correct guess and generate a block. There is a very small probability that more than one block will be generated in the system at a given time. The first node, to solve the problem, broadcasts the block to the rest of the network.
However, the math of solving is very complex and therefore the blockchain stabilizes quickly, meaning that every node agrees on the order of the blocks some time back from the end of the chain. Due to hashing, editing even one bit of the block header will result in a different hash.
RESEARCH SCOPES & RECOMMENDATIONS
- Blockchain in Agriculture .1 Background
- Problem Scope
- Blockchain and Smart Contract Integration in Agriculture Sector
- Detect and Resolve Illegal Actions
- Distributed Database
- Supply Chain Tracking
- Secure Donation Transparency
If we can build a Blockchain network where each block represents a farmer node and the nodes will belong to a single network, then we can have a distributed ledger of ownership data for the countries in that architecture. Here, each block will contain its own information such as land ownership data, land size data, land type data, etc. Using the NG model [17], all the blocks can select a leader based on their requirements, and the newly selected leader block can do the further work.
Leader Block can calculate the costs for the scientific approach to farming and verify whether the aggregated land is ideally suited for this approach. Then the leader block calculates the total cost of the implementation and divides it into phases. This process will be a little complicated, because the land area of each block is different and the costs need to be adjusted depending on the situation of each block.
Later, the leader block will ask for money from each node block based on their cost function. Upon successful transaction, the total balance will be moved and stored in the network. It is not a good idea to give the full authority to write the contracts to the leader block.
But every block should not deploy it as well, as that would be a waste of energy. Thus, a group of blocks must again be randomly selected by the network that will validate the terms of the contracts before they are deployed. Since this is a completely random process and is performed by the Blockchain network itself, there will be no additional overhead.
We can give a more accurate example if we take the case of the current situation of rural farmers in Bangladesh. Through a Blockchain network we can keep the history of any type of product be it bananas or medicine. Since these blocks are linked through hash data, we can easily trace to know what is the origin of each product and what other processes have applied in its life cycle.
CONCLUSION & FUTURE SCOPE
A Risk-Based View of Why Banks Experiment with Bitcoin and Blockchain." Focus on Risk Technology. 8 ZibinZheng, ShaoanXie, Hongning Dai, Xiangping Chen, Huaimin Wang; An Overview of Blockchain Technology: Architecture, Consensus, and Future Trends; Conference Paper, June 2017 (Access date: 20 November 2018). 22 Christian Cachin, Simon Schubert, Marko Vukoli´c; Non-determinism in Byzantine Fault Tolerant Replication; IBM Research; https://arxiv.org/pdf pdf(Access date: 20 November 2018) .
23 How do Ethereum smart contracts work?; https://www.coindesk.com/information/ethereum-smart-contracts-work (Access date: November 20, 2018). 25 Savjee.be; Smart contracts; https://www.savjee.be/videos/simply-explained/smart-contracts/(Access date: November 20, 2018). 26 Kosba, Miller, Shi, Wen, Papamanthou; Hawk: The Blockchain Model of Cryptography and Privacy-Preserving Smart Contracts; University of Maryland and Cornell University; 2016 IEEE;.
27 O'Dair, Beaven, Neilson, Osborne, Pacifico; Music On The Blockchain- Blockchain For Creative Industries Research Cluster; Middlesex University, London. (Accessed: 20 November 2018). Pustogarov, “Deanonymization of clients in bitcoin p2p networks,” in Proceedings of the 2014 ACM SIGSAC Conference on Computer and Communications Security, NY, USA (Accessed November 20, 2018). Moser, "Anonymity of bitcoin transactions: An analysis of mixing services," in Proceedings of Munster Bitcoin Conference, Munster, Germany, 2013 (Accessed: 20 November 2018).
Anonymity for bitcoin with accountable mixes," in Proceedings of International Conference on Financial Cryptography and Data Security, Berlin, Heidelberg, 2014 (Accessed: Nov Swan M.
