# DNS-IdM: A Blockchain Identity Management System to Secure Personal Data Sharing in a Network
## 1 Introduction  
Digital identity is a digital establishment of the particulars obtainable about an entity, and the identity management system ensures that only the valid users are authorized to gain access to that information. Due to the growing usage, the ability to authenticate digital identity has become more significant for the development of technologies, services, and standards [1]. In the era of social engineering, phishing, and spoofing, the identity term gets more complex, and the answer to the question \"Who are you?\" takes a whole other turn [2]. Identity management is a method of recognizing, validating, and authorizing participants to grant access to confidential data. In a number of schemas, service providers, called the relying party (RP), delegate the responsibility of issuing identities, manage credential to an identity provider (IdP), and rely on it to authenticate the access to certain web services [3]. This leverages the user's experience by offering a single identifier valid through different web services. Moreover, some centralized schemas have a single authoritative IdP that is used by several organizations [4]. The RP establishes, beforehand, a relationship with the IdP, and an example of that being Microsoft passport [5]. The main issue arises when the centralized identity management system deprives users of the rightful ownership of their identity data online. Subsequently, with the lack of control, a third party can abuse the trust grantedby users, which raises some privacy and security flags. Similar to other centralized nature systems, the condensed single-point failure becomes a honeypot for malicious attacks. On the other hand, decentralized approaches leverage several IdPs. Those systems agree on a shared protocol between IdPs and RPs that helps dictate the exchange of identities and authorities, like OpenID [6], Security Assertion Markup Language (SAML) [7], and Microsoft's CardSpace [8]. The thing that led to the concept of social sign-on (0 Auth) was rapidly adopted by Google Friend Connect, Twitter, and Facebook. Such services increase the simplicity of access and personal information on social websites, but degrade security and privacy. Single sign-on (SSO) solutions enable HTTP and JavaScript redirection in order to exchange credentials with different layers of communication; however, it is vulnerable to attacks such as malicious identity provider attack, malicious Relying Parties (RP) / Service Providers (SP), and the replay attack. Systems need to improve the level of security, information control flow, simplify authentication, and assertion of credential processes. The decentralized approach is a crucial turning point in identity management to address some issues, such as multiple password sign-ins, efficient management of identities, and delegating the authentication layer. The blockchain is a decentralized, distributed, immutable database infrastructure [9], which revolutionized the idea of cryptocurrency. The wide penetration achievement showed interesting results, but the same technology can be deployed by improving different applications such as healthcare [10], IoT security [11; 12], and asset management [13; 14]. The blockchain can be deployed by reinventing new applications that have never been implemented before [15]. An example of that is the self-sovereign identity management systems. Self-sovereign identity is to accomplish full ownership of identity and tackle those security flags. The need for self-sovereign identity was strengthened by the EU GDPR (2018) [16], which has stressed the user's rights of increased transparency with regulations, privacy by design systems, data portability, and security. With the growing need for security and privacy, the blockchain offers a perfect solution for delivering secure identity services [17]. The distributed ledger technology has given a new perspective on identity management systems, and new approaches transpire, aiming to enhance decentralization, user control, and transparency [18].