Blockchain vs Database: A Critical Analysis PDF

2018 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/ 12th IEEE International Conference On Big Data Science And Engineering Blockchain versus Database: A Critical Analysis Mohammad Jabed Morshed Chowdhury∗ , Alan Col...

2018 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/ 12th IEEE International Conference On Big Data Science And Engineering Blockchain versus Database: A Critical Analysis Mohammad Jabed Morshed Chowdhury∗ , Alan Colman∗ , Muhammad Ashad Kabir† , Jun Han∗ and Paul Sarda∗ ∗ School of Software and Electrical Engineering, Swinburne University of Technology, Melbourne, Australia Email: {mjchowdhury, acolman, jhan, 4949501}@swin.edu.au † School of Computing and Mathematics Charles Sturt University, NSW, Australia Email: [email protected] Abstract—In recent times, Bitcoin has gained special attention business process management and supply chains. In the both from industry and academia. The underlying technology emerging field of the Internet of Things (IoT), blockchain that enables Bitcoin (or more generally crypto-currency) is called technology can be used in different scenarios and forms. blockchain. At the core of the blockchain technology is a data structure that keeps record of the transactions in the network. These include the management of privacy and security of IoT The special feature that distinguishes it from existing technology , as well as the development of new scenarios and business is its immutability of the stored records. To achieve immutability, opportunities. The blockchain technology is also being applied it uses consensus and cryptographic mechanisms. As the data is in higher education. Several higher education institutions stored in distributed nodes this technology is also termed as have employed the blockchain technology to design different “Distributed Ledger Technology (DLT)”. As many researchers and practitioners are joining the hype of blockchain, some of solutions and approaches for managing student records. In them are raising the question about the fundamental difference general, most of the blockchain solutions in education sector between blockchain and traditional database and its real value use the Bitcoin blockchain. or potential. In this paper, we present a critical analysis of both There is little doubt that the blockchain technology is still technologies based on a survey of the research literature where in the initial phase of Gartner’s Hype Cycle for emerging blockchain solutions are applied to various scenarios. Based on this analysis, we further develop a decision tree diagram that will technologies. Government and research organizations are help both practitioners and researchers to choose the appropriate pouring funding for blockchain related research. Recently, technology for their use cases. Using our proposed decision tree the European Commission has announced 30 billion on new we evaluate a sample of the existing works to see to what extent investments in technology initiatives including those involving the blockchain solutions have been used appropriately in the blockchain. However,there is considerable debate in the relevant problem domains. Index Terms—blockchain, database, distributed ledger tech- community about the value of blockchain over a shared nology. database. For example, Narayanan contends that private blockchains are just another name for a shared database. Others, like Greenspan, see several differences between I. I NTRODUCTION private blockchains and SQL databases, from trust building to Blockchain technology aims at creating a decentralized en- robustness. vironment where no third party is in control of the transactions While blockchain is a powerful technology but if it is and data. In general, the blockchain is a time-stamped indiscriminately applied to use cases without considering chain of blocks jointly maintained by all participating nodes. the strength and weakness of the technology, we will fail Blocks are basically containers that aggregate transactions. to realize the true potential of this technology. We have The blocks are chained together cryptographically: each block therefore conducted a scoping review to understand how is digitally signed and ‘chained’ to the previous block by different researchers are using this technology. Our findings including that block’s hash value. New blocks can only be reveal that most of the exiting literatures focus on “how” the appended to the end of the chain, thus the blockchain provides blockchain technology works and, to a lesser extent, on “what” an immutable data storage (existing transactions cannot be (potential) applications and usages that business organizations updated or deleted). For this reason, many systems built on the can leverage. For its part, the “why” question, which focuses blockchain technology achieve secured distribution of digital on the organizational motivations for adopting the blockchain assets among untrusted clients. technology, was scarcely discussed in the literature. Blockchain has been used in several domains due to the The main question we address with this paper is, whether or benefits of distributed data storage and immutable audit trails. not the proposed applications of the blockchain technology as In healthcare, several approaches have been introduced in a solution to problems, have a well-founded basis. In answer- the field of Electronic Health Records (EHR). ing the question above, we make a number of contributions, Due to the transparency of the technology, governments and 1) We have conducted a scope review to see the trend in businesses also try to apply the technology and harvest its the volume and areas of research concerning blockchain benefits in applications such as electronic cash systems, in the last 5 years. 2324-9013/18/31.00 ©2018 IEEE 1348 DOI 10.1109/TrustCom/BigDataSE.2018.00186  2) We have provide a comparative analysis between the opens up the door of opportunities to build and utilize blockchain and database technologies. a system where every possible state or interaction is 3) We propose a decision tree to check whether the use verifiable by the authorised entities. case in hand should use blockchain or not. If yes, what Immutability and irreversibility of chain state: Achiev- kind of blockchain technology should be used. ing a distributed consensus with the participation of 4) Using the decision tree, we have also done a preliminary a large number of nodes ensures that the chain state assessment of the existing literature to gauge the extent becomes practically immutable and irreversible after a to which the proposed uses of blockchain are justifiably certain period of time. This also applies to smart-contracts in terms of the unique advantages that blockchain pro- and hence enabling the deployment and execution of vides. immutable computer programs. In section 2, we give an overview the properties of the Data (transaction) persistence: Data in a blockchain is blockchain technology and its various variants. Section 3 stored in a distributed fashion ensuring its persistency as presents the scoping review of the blockchain technology. We long as there are participating nodes in the P2P network. discuss three popular use cases of blockchain in section 4. Data provenance: The data storage process in any We present a comparison between blockchain and database in blockchain is facilitated by means of a mechanism called section 5. Section 6 presents and discusses a decision-making the transaction. Every transaction needs to be digitally process (in the form of decision tree / flow chart) that helps signed using public key cryptography which ensures the to determine when to use which type of blockchain. Using authenticity of the source of data. Combining this with the this decision-making process, We assess the appropriateness immutability and irreversibility of a blockchain provides of a sample of existing uses of blockchain in section 7. We a strong non-repudiation instrument for any data in the conclude the paper in Section 8. blockchain. Distributed data control: A blockchain ensures that II. B LOCKCHAIN data in the chain are stored in a distributed manner that Bitcoin , introduced in 2008, has emerged as the world’s exhibits no single point of failure. first widely used digital currency and has been used in a wide Accountability and transparency: Since the state of range of applications. Interestingly, it is underpinned by a the chain, along with every single interaction among novel mechanism called the Distributed Ledger Technology participating entities, can be verified by any authorised (DLT), also known as the blockchain technology, providing entity, it promotes accountability and transparency. its solid technical foundation. Even though the terms blockchain and DLT are used inter- III. S COPING R EVIEW changeably in the literature, there is a subtle difference be- In this study we have taken from Arksey O’Malleys tween them which is worth highlighting. A blockchain is just and Levac et. al.’s the guidelines on how to conduct an example of a particular type of ledger, and there are other a scoping review. The procedures proposed by these method- types of ledger. When a ledger (including a blockchain) is ologists maximize both systematicity and transparency which, distributed across a network, it can be regarded as a Distributed in turn, ensure a high level of rigor, reliability, and trust- Ledger. For simplicity, we will also use the terms inter- worthiness. While scoping reviews are systematic in nature, changeably. they must not be confused with traditional systematic reviews. In the last few years, blockchain has received wide-spread Indeed, whereas systematic reviews like meta-analyses attempt attention from the industry, the government and the academia to integrate prior empirical findings on a mature topic in order alike and is regarded as one of the fundamental technologies to provide answers to questions like “what works” and “what to revolutionise the landscapes of several application domains. works best,” scoping reviews attempt to provide an initial At the centre of the blockchain technology is the blockchain indication of the size and nature of the available literature itself. A blockchain is a ledger consisting of consecutive on an emerging topic, to identify gaps, and to propose a blocks chained together following a strict set of rules. The research agenda for future work. In this review, we have ledger is distributed and stored by the nodes of a P2P network tried to identify the research trends in blockchain and which where each block is created at a predefined interval in a application domains have received most attention from the decentralized fashion by means of a consensus algorithm. The blockchain research community. consensus algorithm guarantees several data integrity related properties (discussed below) in blockchain. A blockchain A. Volume and Trend of Research exhibits several properties which make it a suitable candidate We have surveyed three major scholarly indexing databases: for several application domains. The properties are discussed Google Scholar, Scopus and Web of Science, and one re- below. puted publishing venue (i.e., sciencedirect). We have used Distributed consensus on the chain state: One of the “blockchain” as the keyword to search these databases. We crucial properties of any blockchain is its capability to have observed a sharp rise in volume of research over the last achieve a distributed consensus on the state of the chain five years (Figure 1). If we just compare 2016 and 2017, we without being reliant on any trusted third party. This can see that there is 139% increase in Google scholar, 253% 1349  Fig. 3. Tradition SCM vs Blockchain powered SCM By analyzing generic use-cases from the domains, we have tried to find out “why” and “how” blockchain is being used in these use-cases. The identified properties/criteria are discussed Fig. 1. Year-wise number of research publication in more general terms in the next section. 1) Supply Chain Provenance: Supply Chain Management (SCM) is the management of material and information flows both in and between facilities, such as vendors, manufacturing and assembly plants and distribution centers (DC). It keeps record of different interactions between different entities until the delivery of the product to the final point of consumption. Figure 3 shows the interactions of different entities in a traditional and blockchain powered SCM. We can see that in a blockchain powered SCM, all the interactions among different parties are kept in a single blockchain ledger. Therefore, all the parties can see the transaction records related to any particular product. Walmart uses IBM’s Hyperledger (blockchain) technology to track the source of their food and total traceability of the Fig. 2. Subject area wise research publication food at their shelf. Everleger has used blockchain in diamond industry. They have used a combination of public and private blockchain to provide permissioned control and at increase in Scopus, 80% increase in Web of science, and a the same time provides clear audit trail for stakeholders. large 316% increase in sciencedirect1. Critical Analysis Multiple parties are involved in supply chain management B. Subject Areas system and there is a trust deficit among the parties. We have analyzed the “searched data” to find domains Therefore, one entity does not reveal its information to which have received the most attention from blockchain re- other party. Currently, many practitioners solve or by-pass this prob- searchers and practitioners. We have manually gone through all the 843 entries in the scopus database. We have selected the lem by introducing a trusted third party. Both Party A and Scopus database rather than Google Scholar because Scopus B trust the trusted third party and reveal their information. only indexes research publications whereas Google Scholar However, finding a suitable trusted third party is very often includes non-scholarly citations. We have found 673 hectic and in many cases impossible. Blockchain can establish trust among the transacting valid entries out of the 843 entries in Scopus. By valid entries, we mean the entries which are research publication, rather parties (see section V-A for trust building) without a than information about the publication venues or conferences trusted third party. (which is often included in the search result.2 ). Figure 2 shows 2) Inter Bank Transactions: In current banking system, we the numbers of the subject area-wise research publications. can get real-time transactions if we transact within same bank. However, it can take 2-3 business days if the transaction is IV. A PPLICATION D OMAIN A NALYSIS between two different banks. Situation gets worse if it is In this section, we will provide an analysis of three popular an international transaction. International transaction usually application domains to which blockchain has been applied. involves a third bank. The transacting banks need to have an account with this third bank, which are often referred to as 1 As of 14th of February, 2018. Nostro accounts. The problem with current setup is time and 2 All search results can be found at https://tinyurl.com/yb3pvbsa costing. 1350  Due the relatively higher costs of business in inter banking will provide the details of this comparison using different system, bankers are interested to see if blockchain technology criteria described in. We have provided more in-depth can simplify and reduce the cost for inter bank payments. (compared to ) analysis by considering different types Some central banks such as the Monetary Authority of Singa- of consensus mechanisms (in V-D), and attack vectors (e.g., pore (MAS) and the Bank of Canada are working on solutions DDos (in V-C), 51% attack (in V-E)). to use distributed ledger technology for interbank payments A. Trust Building ,. Ripple , which is a crypto-currency, has been proposed to provide global settlement network based on One of the most important features of blockchain technol- blockchain. It has most impacted the traditional banking sector. ogy is immutability. The immutability is achieved by decen- In fact this is the first kind of crypto-currency that bridges the tralized consensus mechanism. Each participating node takes gap between the virtual currency market and the traditional part in a consensus mechanism to check whether any particular banking sector. transaction is valid or not. Every node in the system has the Critical Analysis same level of access (e.g., in terms of public blockchain) and capability. This provides a solid foundation for building Blockchain has potential to be used for fast inter-bank trust, because it democratize the whole system. In a traditional payment transactions. database, we have to rely on a single central authority which Performance is a vital in banking system. Blockchain in controls who can do what in the system. This kind of system its current form could not be able to handle the volume is good when the party who controls the system is trusted and of transaction in current banking system. behaves honestly. However, a consortium could be built to create and manage the crypto within that particular network. By this B. Confidentiality and Privacy way the consortium can fix the price of that crypto for There is a misconception about blockchain is that data in that network. blockchain is kept encrypted. However, this is not true. The 3) Health Care: In current health-care system, different data is digitally signed by the the transacting parties but not providers keep record of their patients and they often cannot or by default encrypted. In fact, it is an open ledger system, do not share their data with other providers. Health data is very where anybody can join and verify any transaction in the private and the patients often have to blindly trust the health network. However, the privacy or confidentially of the partici- care provider. In addition, accessing and sharing health record pating parties are kept by using public key cryptography. The usually takes lot of admin time for the doctors and the patients. transactions reveal the transacting parties and the data in the The vision of blockchain in health care system is to reduce the transaction (e.g., amount of coin in case of crypto-currency). administrator time for the doctors so that they can spend more Recently, researchers are proposing strong anonymization us- time with their patients and sharing of data. Researchers from ing cryptographic means such as Zero Knowledge protocol MIT has proposed a blockchain based health record system. called MedRec which restores patients’ control over their C. Robustness/Fault Tolerance medical data. It links patient’s medical records from different doctor’s database and allow the patient to share with any care Blockchain is a decentralized system and uses distributed provider. computing mechanism to provide robustness and fault tol- Critical Analysis erance. Data in the blockchain is stored distributedly. Each participating nodes stores a copy of the blockchain. There- Health-care is fundamentally very complex and sensitive fore, it can all types of cyber attacker that is relevant for sector. Adaptation of technology is always very slow due single point of failure. Attacks like Denial of Service (DoS) to legislative requirements. and Distributed Denial of Service (DDoS) are infeasible in However, interoperability and collaboration are very im- blockchain network. If any particular node goes down or got portant in this sector for service delivery and innovation. compromised then other nodes can still continue the job. Blockchain can be used to enable interoperability and collaboration without compromising the security of the D. Performance health care providers. Blockchain, specially bitcoin is notoriously slow. It takes Applying blockchain in health sector without rigorous 10 minutes to confirm a transaction in the network. This time research and usability test could be catastrophic. For ex- could go up to 60 minutes if there is any soft fork happens ample, doctor’s access may get delayed due to scalability in the network. Traditional system database systems can be issue of blockchain in a critical moment, which may designed to handle thousands of transactions per second. For cause bad consequences. example Visa and Mastercard networks can handle 50,000 transactions per second. If the system administrator finds a V. C OMPARISON BETWEEN B LOCKCHAIN AND DATABASE performance bottle neck, he can replace or re-engineer the T ECHNOLOGY system to allow high volume of transaction. Table I has summarized the comparison between database However, in terms of performance there are research going and two versions of blockchain. In the following section, we on to improve the efficiency of the consensus mechanism. 1351  TABLE I C OMPARISON OF D IFFERENT A PPROACHES WITH O UR P ROPOSED A PPROACH Issue BlockChain Central Database Advantage Trust Building Can operate without any trusted party Need a central trusted party Blockchain Confidentiality of Data (by default)All nodes have visibility of the data It restricts access to authorized person Database Robustness/Fault Tolerance Data is distributed among nodes data is stored in central database Blockchain Performance Takes time to reach consensus (e.g., 10 mins for Bitcoin) Immediate execution/update Database Redundancy (by default)Each participating node has the latest copy Only the central party has copy Blockchain Security (by default) Use cryptographic measures uses traditional access control Blockchain Consensus algorithm like Ethash and X13 can come Start to an consensus within 10 to 20 seconds. Yes No Aretheremultiple E. Security parties? The security of blockchain comes, in part, from its adapt- No Isthereanytrust deficitamongparties? ability. The more users the system has the more users can be required to achieve consensus. In Blockchain protocol, a block Yes will be accepted if 51% of the mining nodes agree. Therefore, Yes Isthereanytrusted thirdparty? if 51% of the mining nodes are controlled by the malicious users then an “invalid transaction” can be accepted as “valid No transactions”. If there are enough people in the network, it No Shouldtherecordof transactionsbe seems impossible but it can happen. immutable? In terms of traditional database, the state of the database is Yes maintained by a central system. Access to the data is restricted Isscalabilitya critical requirement? by the access control mechanism set by that system. This No system is vulnerable, if the system administrator of the system is compromised. Useblockchain VI. W HEN SHOULD WE USE BLOCKCHAIN ? No Yes Ispublicverifiability From the above discussion, it should be clear that important? blockchain is not a general purpose technology but should Usepublic be applied judiciously to reap its benefits. Figure 4 provides Useprivate blockchain blockchain a simple decision flow control diagram that can be used by the business analyst or system architect to decide whether No Yes No Yes Isdatadurability Isdatadurability blockchain should be used or not. important? important? In general, blockchain technology is useful in those use- cases where there are more than one administrative authority UseOffͲchain UseOnͲchain UseOffͲchain UseOnͲchain UseDatabase storage and there is a trust deficit among those parties. A typical storage storage storage example could be a supply chain management system, where multiple parties collaborate together to deliver goods. Another Fig. 4. Decision Tree to determine the use of blockchain example could be a consortium of independent companies working on a government project, where there is a trust deficit between the parties. VII. A SSESSMENT OF E XITING U SE OF B LOCKCHAIN Currently, if there is a trust deficit among the collaborative We have analyzed a sample of 100 papers among the parties, they usually select a trusted third party which both 800+ papers surveyed from Scopus using our decision tree parties trust. For example, both buyer and seller trust bank model (see figure 4). We have found that the majority of the to transact money among themselves. However, sometimes 100 papers are theoretical papers related to core blockchain finding a trusted third party is challenging or risk prone. technology. We have identified 34 papers which are related to If all the criteria above match then we can say that use cases or their implementations. In our analysis, we have blockchain is a beneficial technology for that use-case. How- found that among these 34 papers, 25 papers have used the ever, now we have to decide whether we should use public blockchain appropriately (e.g., used the unique properties of blockchain or private blockchain. If the stored value in the blockchain), whereas the used cases in the other 9 papers blockchain needs to be publicly verifiable then we should use could have used traditional databases to achieve the same public blockchain, whereas if the data is only for specific functionality. parties then a private blockchain is a better choice because We have found that 9 papers out of 25 papers(which used consensus mechanisms can be simplified. the unique properties of blockchain) are related to supply chain 1352 management system and power grid. Blockchain has emerged Samaniego M, Deters R. Blockchain as a Service for IoT. 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