Research Article Blockchain Technology: Is It a Good Candidate for Securing IoT Sensitive Medical Data? Nabil Rifi, 1,2 Nazim Agoulmine , 1 Nada Chendeb Taher , 2 and Elie Rachkidi 1 1 COSMO, IBISC Laboratory, University of Evry, Paris Saclay University, France 2 Lebanese University, Faculty of Engineering and Azm Center for Researches, Tripoli, Lebanon Correspondenceshouldbe addressedto NazimAgoulmine; nazim.agoulmine@ufrst.univ-evry.fr Received 15 August 2017; Revised 19 December 2017; Accepted 25 June 2018; Published 5 December 2018 Academic Editor: FernandoDe la Prieta Copyright ©2018NabilRifetal.TisisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense,which permits unrestricteduse,distribution, and reproductionin any medium, provided the original work is properlycited. Inthepastfewyears,thenumberofwirelessdevicesconnectedtotheInternethasincreasedtoanumberthatcouldreachbillions in the next few years. While cloud computing is being seen as the solution to process this data, security challenges could not be addressed solely with this technology. Security problems will continue to increase with such a model, especially for private and sensitivedatasuchaspersonaldataandmedicaldatacollectedwithmoreandmoresmarterconnecteddevicesconstitutingtheso called Internet of Tings. As a consequence, there is an urgent need for a fully decentralized peer-to-peer and secure technology solution to overcome these problems. Te blockchain technology is a promising just-in-time solution that brings the required propertiestothefeld.However,therearestillchallengestoaddressbeforeusingitinthecontextofIoT. Tispaperdiscussesthese challenges and proposes a secure IoT architecture for medical data based on blockchain technology. Te solution introduces a protocol for data access, smart contractsand a publisher-subscribermechanism for notifcation. A simple analytical model is also presentedtohighlighttheperformanceofthesystem.Animplementationofthesolutionasaproofofconceptisalsopresented. 1. Introduction IoT is taking over the world; it is estimated that the number of devices connected to the Internet forming the Internet of Tings will reach 50 billion by 2020 [1]. One critical application is the eHealth smart homes. In fact, this technol- ogy allows monitoring elderly or individuals with diseases and automatically sending the data to a remote server for processing by doctors. Tis data is recorded in the so-called EMR (Electronic Medical Record). Secure access to this EMR is problematic considering privacy issues, transparency, etc. Tis is why in order to develop secure and reliable solutions for eHealth smart homes, it requires unprecedented coordination and collab- oration between all pieces of the system. All devices must work together and be integrated with all other devices, and all devices must communicate and interact seamlessly with remote systems and infrastructures in a secure way. Such a solution is possible, however it can be expensive and time consuming. Tus, there is a need for new ideas and new technologies that will drive IoT security towards a more decentralized model. Having this huge amount of data, being centralized and sometimes monitored by one single provider, may create many problems. Te cloud as a computing/storing technol- ogy cannot only by itself protect the security and privacy of its users. Using a decentralized approach for IoT network security is eventually an interesting way tosolve many of the challenges IoT technology is facing today. Adopting a peer- to-peer model to handle billions of transactions between the billions of interconnected devices will decrease dramatically the costs of installation and maintenance of data centers and servers. It will also allow the distribution of storage and processing power on diferent devices and components of the network increasing the reliability of the system; e.g., the failure of one node will not cause the entire network to halt or collapse. However, in order to establish well-defned peer-to-peer communicationprotocols,awholeothersetofchallengeswill needtobeaddressed,mainlysecurityandprivacy.Somelevel Hindawi Wireless Communications and Mobile Computing Volume 2018, Article ID 9763937, 11 pages https://doi.org/10.1155/2018/9763937