# An Accelerated Method for Protecting Data Privacy in Financial Scenarios Based on Linear Operation
## 2 Related Work  
Nowadays, blockchain technology is being used within the field of financial security. Blockchain is a P2P (peer-to-peer) distributed database and is a web-based concept. It consists of a series of blocks containing transactions, timestamped and verified by the network community and protected by a PKI (Public Key Infrastructure). An element of the blockchain cannot be modified after it has been added to the blockchain. Moreover, it retains a permanent account of earlier actions [23]. Furthermore, blockchain is expected to initiate an industrial and commercial revolution, while contributing to global economic reform. First, blockchain uses cryptography to create a secure code in digital form. Users can then confirm purchases without having to provide any personal data. Since blockchain records are immutable, transactions are automatically completed and decentralised [24]. The blockchain is a secure database and decentralised transaction system driven by decentralised nodes [25]. In other words, blockchain is a game-changing technology that has attracted the attention of businesses and governments worldwide. Essentially, the term \"distributed ledger technology\" refers to the collection of transactions and data that are sequentially tracked and registered on a network of distributed ledgers [26]. A blockchain is also divided into an ever-expanding list of records, called blocks, linked together using cryptography [27]. Blockchains are used as transaction ledgers in cryptocurrency systems such as Bitcoin and Ether, where the blockchain records the current state and previous transactions. Blockchains can additionally be defined as collections of blocks that store data in a hash function and include a link to the previous block and timestamp [28]. A blockchain is a distributed database that only allows new data to be appended to existing data [29]. Based on this feature, blockchain technology plays an important role in the financial sector. The first generation of blockchain technologies acted as currencies, such as Bitcoin. In addition to Bitcoin, the most prominent cryptocurrency, about 600 other cryptocurrencies have been established and are used as exchange tokens in Bitcoin-based applications. Ether, Monero, and Ripple are the other most popular ones [30]. The second generation of blockchain technology is not only about cryptocurrency transactions but also about bonds, smart contracts, futures, loans, and mortgages. The integration of smart contracts with the blockchain is the most critical feature of this phase. When certain criteria are met, smart contracts are parts of code buried within them that react in a specific way [30]. Furthermore, blockchain can solve the problem of e-commerce reputation schemes that use the registration of a large number of fake customers to gain a high reputation; the reputation information is not reversible because it is stored on the blockchain and all reputation changes are easily detectable. For security enhancements, blockchain can solve the problem of a single point of failure of an important central node. And since it can reduce the impact of attacks on public and private key distribution devices, Blockchain can help build more reliable public-private key infrastructures [31]. Blockchain technology can also be used for privacy protection in the financial sector, where a data storage system built on blockchain can guarantee the anonymity of users while ensuring their ownership of data [32]. In addition, cloud computing is being widely used in enterprises. For large enterprises and governments, much of the appeal of the cloud lies in better control and reduction of data centre costs. In particular, cloud computing allows the reclassification of IT expenses from capital expenditure to cash-based 'operational expenditure' [33]. Another business benefit of cloud computing is reduced demand for skilled labor in places where there is a shortage of high technology (e.g., South East Asia) [34]. Moreover, it lowers the barrier to entry into computing [35; 36; 37].