© 2018, IJCSE All Rights Reserved 488 International Journal of Computer Sciences and Engineering Open Access Survey Paper Vol.-6, Issue-12, 2018 E-ISSN: 2347-2693 Issues and Challenges with Blockchain: A Survey Divyakant Meva Faculty of Computer Applications, Marwadi University, Rajkot, India * Corresponding Author: divyakantmeva@gmail.com, Tel.: +91-98259-51824 Available online at: www.ijcseonline.org Accepted: 19/Dec/2018, Published: 31/Dec/2018 Abstract- Blockchain is one of the latest trends in Information Technology domain. It has changed a way of thinking for IT professional. Companies are focusing on implementation of blockchain with their services to ensure security and reliability. Still they are facing challenges and issues for development and implementation of blockchain based services. This paper discusses those issues and challenges to be considered in development and implementation. Keywords—Blockchain, Smart contracts, Issues and Challenges (key words) I. INTRODUCTION When we talk about blockchain, first thing which comes to our mind is Bitcoin. This crypto currency was first one to use concept of blockchain for implementation purpose in the year of 2009. Bitcoin brought the concept of blockchain and smart contracts in to the knowledge of every one. Stuart Haber and W. Scott Sternest started first work on a cryptographically secured chain of blocks in 1991 and continued till the mid 2000’s. It was Satoshi Nakamoto who conceptualized first blockchain in 2008 and then it as a core component of Bitcoin. A. Blockchain Blockchain is not just one concept, but combination of multiple concepts like cryptography, mathematics, networking, distributed consensus technology, algorithms etc. [1].It is trying to solve problems with distributed database synchronization with distributed consensus. The characteristics of Blockchain technology are: 1. Transparent 2. Distributed 3. Autonomy 4. Immutable 5. Anonymity 6. Open source B. Smart contract The term smart contract is a bit confusing as neither this is smart nor is a legal contract. Smart contract is a code running on top of the blockchain technology containing a set of rules with which parties under that contract will agree to interact with each other. If the defined rules meet, the agreement will automatically be enforced. The code verifies, facilitates and enforces performance of agreement or transaction. This is one of the simplest forms of decentralized automation. Smart contracts reduce transaction cost. Characteristics of smart contracts are: 1. Self executing 2. Self verifying 3. Tamper resistant After taking introduction to blockchain, the section II gives idea about working of blockchain. Section III focuses on working of smart contracts. Section IV then discusses issues related with blockchain. Section V gives idea about challenges related with blockchain. At the end, section VI concludes the discussion on issues and challenges related with blockchain. II. WORKING OF BLOCKCHAIN Here are the important concepts of working of blockchain: 1. The record: It can be any information or a deal 2. The Block: It is bundle of records 3. The chain: When all the blocks are linked together, it forms a chain The process steps: 1. Ina trade, record is created; Mr. X is selling three of his coins to Mr. Y for 2000 Rs. This record lists details including digital signature from each participating party. 2. This record will be checked on to network. The nodes – computers on network, will check the details of record or trade, to assure validity of the trade