Due to the expeditious evolution of wearable technology and wireless mobile networks, the tele-medicine and mobile medications have turned up into the Telecare Medicine Information System (TMIS). The efficient management of the patient’s Electronic Health Record (EHR) plays a vital role for the telecare of patients that include medication for the chronic patients, long-term telecare for the special patients, analysis of patients infected with certain disease etc. The sharing and distribution of EHRs with medical practitioners can enhance accuracy of the diagnosis; however, privacy and security preservation of patients’ record are the detracting issues of this system. Recently, due to the property of immutability, blockchain technology has been introduced to be as an auspicious solution for achieving EHR sharing with privacy and security preservation. This work puts forward a novel blockchain-based privacy and security preserving EHR sharing protocol for improved diagnosis and efficient treatments in TMIS. Firstly, two types of blockchains, named as private blockchain and the consortium blockchain, are constructed by formulating their consensus, data structures and mechanisms. Private blockchain is in-charge of maintaining EHRs, while consortium blockchain stores EHRs’ secure indexes. In order to attain data security, secure search, access control and privacy preservation, all the EHRs are public-key encrypted with appropriate searchable keyword. Security analysis of our protocol validates that our protocol achieves all the security goals by exempting several security attacks. For achieving efficient computational results, the user and server sides of our scheme are implemented separately. Furthermore, performance analysis of our protocol with other existing protocols reveals that our protocol is relatively better in terms of the communication and computation overhead by providing notable level of the security.

由于可穿戴技术和无线移动网络的迅速发展，远程医疗和移动药物已发展成为远程医疗信息系统（TMIS）。病人的电子健康记录（EHR）的有效管理对于病人的远程护理起着至关重要的作用，包括为慢性患者提供药物，为特殊患者提供长期的远程护理，对感染某些疾病的患者进行分析等。向医生分发电子病历可以提高诊断的准确性；但是，保护患者病历的隐私和安全性是该系统的不利因素。最近，由于不变性，引入区块链技术是一种实现隐私和安全保护实现EHR共享的吉祥解决方案。这项工作提出了一种新颖的基于区块链的隐私和安全保护EHR共享协议，以改善TMIS中的诊断和有效治疗。首先，通过制定共识，数据结构和机制，构建了两种类型的区块链，分别称为私有区块链和财团区块链。私有区块链负责维护EHR，而联盟区块链则存储EHR的安全索引。为了获得数据安全性，安全搜索，访问控制和隐私保护，所有EHR均使用适当的可搜索关键字进行了公钥加密。对协议的安全性分析通过免除几种安全攻击，验证了我们的协议已实现所有安全性目标。为了获得有效的计算结果，我们的方案的用户和服务器端分别实现。此外，对我们的协议与其他现有协议的性能分析表明，通过提供显着的安全级别，我们的协议在通信和计算开销方面相对更好。