Short Review on Block Chain

Introduction:

Blockchain technology has huge potential with a variety of applications and provides wideopportunities for various infrastructure.The technology encourage resource managementand makes communication both secure and efcient. Trust is increased when conductingnancial transactions among parties using Blockchain, as it reduces the chances of swindle and automatically produces a record of activities. Creating an automated background check of any member of the system. Due to its decentralized properties, Blockchain creates reliability and reduces the risk faced when looking to enter a business agreement with an unfamiliar party.

Today all people were using advanced technology for communication through internet. Voice call, video call, messages, pictures, are travel directly from sender to receiver over the internet. For this transaction, must maintain a trusted third party between these sender and receiver. When it comes in the case of money transaction, people have to trust a third party for complete this, in traditional system. But in the case of blockchain it will give a perfect security in transaction. A block should record every transaction, it will act like a record book. Once completed a transaction a block goes into the blockchain as a permanent database. If a block is completed a new block is added with this or a new block is generated. Every block carry a hash of the previous block.

Blockchain overview:

In principle, a blockchain should be considered as a distributed append-only timestamped data structure. Blockchains allow us to have a distributed peer-to-peer network where non-trusting members can verifiably interact with each without the need for a trusted authority (Christidis and Devetsikiotis, 2016). To achieve this one can consider blockchain as a set of interconnected mechanisms which provide specific features to the infrastructure, as illustrated in Fig. 1. At the lowest level of this infrastructure, we have the signed transactions between peers. These transactions denote an agreement between two participants, which may involve the transfer of physical or digital assets, the completion of a task, etc. At least one participant signs this transaction, and it is disseminated to its neighbours.

 

A valid transaction means, for instance, that Bob received one bitcoin from Alice. However, Alice may have tried to transfer the same bitcoin, as it is a digital asset, to Carol. Therefore, nodes must reach to an agreement on which transactions must be kept in the blockchain to guarantee that there will be no corrupt branches and divergences (Vukolić, 2015, Christidis and Devetsikiotis, 2016). This is actually the goal of the second Consensus layer. Depending on the blockchain type, different Consensus mechanisms exist (Mingxiao et al., 2017). The most well-known is the Proof-of-work (PoW). PoW requires solving a complicated computational process, like finding hashes with specific patterns, e.g. a leading number of zeroes (Antonopoulos, 2014), to ensure authentication and verifiability. Instead of splitting blocks across proportionally to the relative hash rates of miners (i.e., their mining power), Proof-of-Stake (PoS) protocols split stake blocks proportionally to the current wealth of miners (Pilkington, 2016). This way, the selection is fairer and prevents the wealthiest participant from dominating the network. Many blockchains, such as Ethereum (Dannen, 2017), are gradually shifting to PoS due to the significant decrease in power consumption and improved scalability. Other consensus approaches include Byzantine Fault Tolerance (BFT) (Castro and Liskov, 2002) and its variants (Zheng et al., 2016).

 

An additional layer, the Compute Interface, allows blockchains to offer more functionality. Practically, a blockchain stores a state which consists e.g. of all the transactions that have been made by the users, thereby allowing the calculation of each user’s balance. However, for more advanced applications we need to store complex states which are updated dynamically using distributed computing, e.g. states that shift from one to another once specific criteria are met. This requirement has given rise to SCs which use nodes of the blockchain to execute the terms of a contract.

 

Finally, the Governance layer extends the blockchain architecture to cover the human interactions taking place in the physical world. Indeed, although blockchains protocols are well defined, they are also affected by inputs from diverse groups of people who integrate new methods, improve the blockchain protocols and patch the system. While these parts are necessary for the growth of each blockchain, they constitute off-chain social processes. Therefore, blockchain governance deals with how these diverse actors come together to produce, maintain, or change the inputs that make up a blockchain.

 

PUBLIC AND PRIVATE BLOCKCHAIN:

Blockchain is mainly divided in to three types. Public,Private and consortium blockchain.This paper focusing on the comparison between public and private blockchain based on some recent property. Public and private blockchain should have many similarities as well as differences in it’s functionality.

CHALLENGES IN BLOCKCHAIN:

Blockchain has faced some challenges in industry especially during bitcoin transaction. Those problems inherent to functions of the Bitcoin blockchain are compiled below.Summaries some typical challenges below[. Scalability The amount of transactions are increasing day by day. Most of the companies were suggesting blockchain for their transaction process. All transaction have to be stored and it will be validated. The capacity of the block will very small. Some transaction must be delayed due to miner prefer high transaction fee to those transaction. So the large block size will lead to reduce the propagation speed. There fore scalability problem is quite though. There some methods to avoid the scalability problem in blockchain

• Storage Optimization of blockchain


• Redesigning blockchain

Privacy Leakage:

Users believed that blockchain gives better privacy when handling sensitive data. In blockchain users could only generate address instead of their identity. In 2013Meiklejohn and in 2016 Kosba shows that blockchain cannot guarantee the transnational privacy. Recent study shows that bitcoin transactions are linked together to an account address to reveal the identity of user. The problems were leak out the users identity Elliptic Curve Diffie- Hellman- Merkle(ECDHM) can be used to overcome this problem. It will deals with public and private key. This will exchange shared secrets between two people.It will helps to secured message transaction0n over the internet. A secured platform like smart contract and ethereum is also developed to keep secured transaction.

MITM Attack:

MITM  means Man in The Middle Attack. This is known as third party interaction. Here a user came in the middle, who may have a forged public key. By using this key, he can easily decrypt the sensitive data. In blockchain public key is distributed across the participating nodes. Each block should be connected with a link to previous and following blocks. Because of this, the public key is immutable it should not attack by any forged keys.

DDoS Attack:

Distributed Denial of Service attack (DDoS) is an attack  which is target to attack one particular system Such as c computer, website, server or other network resources. Therefore, the incoming messages or connection to the target system may slow down, or even crash or shut down. Especially in blockchain DDoS attack create some significant business risk. Practically it is impossible to prevent this type of attack.

 

SECURITY FEATURES OF BLOCKCHAIN

• Use ledger. Ledger should record each and every transaction in a blockchain. This ledger is immutable. Existing data cannot be edited or deleted. In blockchain technology these ledger is decentralized application. So, no one can access the transaction or even any sensitive data from this ledger . People can only read the information from a ledger.


• Another type of security feature is the chain of block. In blockchain each block should contain a hash value. These blocks are connected by its previous hash. Suppose an attacker came to correct the data, then its hash will be changed. It will affect the overall chain. So, it will increase the protection of sensitive data or information.


• Blockchain technology is a decentralized application. Mainly it will support peer to peer communication. So, in a network node is considered as computers. These thousands of nodes should have the copy of distributed ledger. This should be authenticating the transaction. If any of the node does not agree a transaction, then it cannot be proceeding. So, it will be cancelled. This will protect from a fraud transaction.

 

APPLICATIONS OF BLOCKCHAIN TECHNOLOGY:

Blockchain for health care industry In today’s life patient doesnt like to reveal there treatment details to outsider. In this case patient can use this technology to keep secure all information from others. This blockchain can be used as a website, or mobile app. Each and every user in a blockchain has two keys. Public key and private key. By using this only who can make a transaction. For example there two person Alice and Bob. Alice want to send some secure data to bob. So that Alice sign a digital signature by using here private key. That means private key is always act like as a password. Then shew will hash the data by using here public key and generate an address. Then bob validate the digital signature. If it is validated they will make a transaction. So by using these type of security methods, potions information can be protected from others.

Electronic medical records. Patients can handle electronic medical records by using the blockchain technology. Most of the health cares institution should not allow patient to access their medical data. Patients are becoming disappointed about the privacy of their medical records. This all can be avoided by blockchain. In handling electronic medical records, blockchain should deal with different frame work for managing the authentication, confidentiality, and accountability. It is mainly used when handling the sensitive data. Online electronic records in blockchain will operated as decentralized application. In centralized environment all application should be done at one location. But in decentralized environment application should be done in different location. Electronic medical records should affect some challenges and limitations. This system will face some important challenges during the implementation of personally controlled system. That is this personally controlled records would replace provider or hospital records. Some segment of the personally controlled records would be downloaded in to the institutional record to tribute the existing data This challenges can be avoided by blockchain. Because blockchain leads a key exchange based transaction between two parties. Their personal identity does not revel to any others. Because 5 1234567890‘’“” RAEREST IOP Publishing IOP Conf. Series: Materials Science and Engineering 396 (2018) 012030 doi:10.1088/1757-899X/396/1/012030 they are only providing their key identity. Each and every user in a blockchain should have one public key and one private key.

Blockchain to protect personal data Today there is recent increase in reported incident of security problem in users personal data. Because of this there is a third party control over the data, who will collect all personal information. Blockchain can eliminate this third party and can transfer directly between two parties. The amount of data recently increasing in our world. Facebook, is the largest online socialnetwork, collected 300 petabytes of personal data. Personal data or sensitive data should not be secure in the hand of third parties. They are tried to attack and misuse. Blockchain helps users that not required to trust any third party. Blockchain recognizes the users as the owners of their personal data. Blockchain should have its own rules and regulation. It is known as smart contract. Before starting a transaction the gateway keeper should create some rules and will written as a contract. It will make a peer to peer communication. Bitcoin has demonstrated in financial space that is trusted and computing is possible in decentralized network. Blockchain is mainly proposed to handle the bitcoin, it is a digital currency.

Bitcoin In 2008 bitcoin is invented as a new way to send value over the internet. Vitalik Buterin,is a programmer, introduced bitcoin in 2011.  Bitcoin is a digital currency, created and held electronically. It is operated as a decentralized application. That directly control the transfer of digital currency. Value of bitcoin increasing in recent year. Bitcoin sets out to solve the distributed tracking and validation of transactions is one ot its main problem. It will keep the full history of transaction. Blockchain is mainly developed to transact this digital currency. If the user wants the recent history, then who can filtering it. Before making a transaction the rules and regulations of this will be written as a contract form known as smart contract. Transaction is only possible between two persons, before making it sender side should enter a digital sign. The transaction is validated by this digital sign. If this sign is validated transaction is proceed, that means botcoin should transacted.

 

CONCLUSION:

Blockchain is an amazing topic in recent year, it will support different applications. Blockchain will give Better security during transaction of any value. This technology is mainly proposed to handling bitcoin transaction.Smart contract, Ethereum and distributed ledger are some applications of blockchain, This will also give more security. Best suited and mostly used application of blockchain bitcoin. Blockchain gives faster and cheaper transaction than any other application. It will provide a better security especially to sensitive data. Blockchain applications often see additional benefits in its transparency and immutability.