# DynamiChain: Development of Medical Blockchain Ecosystem Based on Dynamic Consent System
## 1 Introduction  
As part of the fourth industrial revolution in recent years, the advancement in blockchain technology has brought back the original theorem regarding smart contracts. Such algorithms based on computer protocols were designed to automatically facilitate, verify, and enforce the negotiation and implementation of digital contracts within an authority distributed architecture [1, 2, 3]. Smart contracts are being applied to a wide range of fields, mainly from the digital economy to healthcare, and the Internet of Things (IoT) [4]. To date, there is still a trend to use mainstream blockchain platforms, such as Bitcoin and Ethereum, when developing such platforms [5, 6].  
However, smart contract-related core technology is still in its infancy, and major technical challenges regarding security breach and privacy issues still exist. For example, blockchain cannot guarantee transactional privacy, since the values of all transactions and balances for each public key are publicly visible [7, 8]. Moreover, a user's Bitcoin transactions can be linked to reveal user's information [9]. Similarly, each client can be uniquely identified by a set of nodes it connects [10]. \"DAO Attack\" that occurred in June 2016 [11, 12, 13] might be one of the most well-known blockchain targeted attacks. Itwas a severe incident that resulted in a loss amounting to more than $50 million Ether (approximately worth more than 8.5 billion dollars at that time) being transferred to an unauthorized account. This type of security breach is particularly sensitive in the medical industry, where personal health or medical information is being transferred within the network. In addition, contemporary blockchain-converged solutions do not consider restricted medical data regulations that are still obstacles in many countries worldwide.  
In addition, current medical systems lack evidence-based data sharing policy, making it difficult for data providers to control their data based on their desired settings or policies. Some of the core values that blockchain technology aims to achieve, which are distributed authority, and consensus-based security, could play a vital role in providing these data providers with the rights they have over their own health data. This implies a crucial need for a system or solution that is suitable for the healthcare sector.  
This paper, therefore, proposes the development of a medical blockchain ecosystem based on a dynamic consent system. The proposed solution not only solves security issues by using blockchain technology, but also tackles the problem of privacy piracy by adopting a dynamic consent algorithm original to this research. Our developed system was applied in a practical healthcare business application scenario focusing on actual physical examination of big data being used for health services. Moreover, a medical blockchain-related studies were reviewed to prove the novelty of the system in terms of dynamic applicability and expandability. The proposed solution is envisioned to provide a successful example for future blockchain applied medical systems to be extended to other disease areas or medical databases.  
The rest of this paper is organized as follows. Section 2 gives a brief review of the state-of-the-art approaches for blockchain technology. Section 3 provides comprehensive details of the whole DynamiChain. Section 4 describes the specific implementation of DynamiChain. Section 5 highlights the novelty of DynamiChain, and finally, the Section 6 concludes the discussion with the extension of DynamiChain in the future.