# DNS-IdM: A Blockchain Identity Management System to Secure Personal Data Sharing in a Network
## 1 Introduction
The blockchain provides a way out of the security and privacy holes that have been there since the dawn of the Internet, away from a central authority [19]. In the current age of digitization services like healthcare, social, and financial service, to name a few, all rely on user identities [20; 21]. The management of user identities has grown far beyond validating a unique combination of user name and password. Digital services rely on identity attributes, which define an individual user in the real world, for instance education, profession, social status, and medical history, among others. This reliance has opened up further challenges of identity attribute verification as various distinct benefactors bestow these attributes: education by the education department, profession by professional bodies, and healthcare by health and social care services, etc. The proposed DNS-identity management (IdM) offers a domain name system-like experience for identity management. Through DNS-IdM, an individual can make use of real-world attributes of his/her identify to create a digital identity that can be seamlessly utilized by service providers to validate the user and offer their services based on verified attributes. The use of the blockchain as a secure and trusted network to provision identities (with associated attributes) and exploitation of smart contracts to securely acquire identity attributes from respective benefactors sets apart DNS-IdM, not only from conventional identity management systems, but also from the latest developments in blockchain-based identity services. Conventional identity management systems mainly rely on third parties to verify the claims about the identity attributes, which once verified, remain valid even if revoked or updated by the benefactors; whereas, blockchain-based identity services either solely rely on users to define their identity attributes or enable users to control the disclosure of the attributes based on their acceptability. DNS-IdM enables users to manage their identities, whereas for service providers, it enables them to make use of existingidentity attributes and, if the required attributes do not exist, directly request them from benefactors through smart contracts. The entire process of identity management (i.e., attribute persistence, request, and verification) is seamlessly executed by the combination of a permissioned and permissionless blockchain coupled with smart contracts. In the intrinsic properties of the blockchain, tamper-resistant, permanence, and traceability make the DNS-IdM secure and trustworthy. The major contributions of this paper are as follows:  
* An analysis of three decentralized identity management systems revealing their weaknesses. * A novel decentralized IdM architecture, with attribute associated validators, which overcomes the existing drawbacks and maximizes security. * An evaluation to show that the DNS-IdM design is highly scalable, enhancing validators to be added to the network considering the new attributes introduced. * Minimum disclosure by the RP smart contracts, which can be edited and customized to the best interest of the user before being added to the network. The rest of this paper is organized as follows. Section 2 presents the background discussing the digital identity concept and the Ethereum-based IdM framework in depth. Section 3 analyses the three most advanced identity management systems by revealing their major limitations. Section 4 proposes the new architecture model that needs to be deployed on the Ethereum framework. Section 5 includes three experiments to demonstrate the security benefits of DNS-IdM. In Section 6, we summarize the use-case of DNS-IdM. Section 7 presents a comparison evaluation by focusing on security and scalability issues. Finally, the concluding Section 8 discusses the overall outcome of the work.