## 2 Related Works
### Literature Review
#### 2.2.3 Novel Contributions  
Recent advances in decentralized identity management (DIdM) using distributed ledger technologies (DLT) have significantly improved the security, scalability, and privacy of IoT systems. Key innovations include a location-based DLT identity architecture for edge devices, a semi-decentralized blockchain framework for secure device identification via smart contracts, and the integration of Self-Sovereign Identity (SSI) into the IoT with a novel TLS 1.3 handshake protocol. In addition, Hierarchical Identity-based Encryption (HIBE) has been introduced to reduce computational complexity and improve access control, while a multi-layered Identity and Access Management (IAM) framework has been proposed to ensure data integrity. Research has also focused on overcoming identity isolation and regulatory challenges through decentralized Web of Trust-based frameworks while emphasizing the need for further exploration of DLT solutions in IoT ecosystems. These contributions pave the way for more robust, scalable, and user-controlled identity systems, with practical applications and performance improvements demonstrated in real-world IoT environments. Table 1 summarizes the main contributions and limitations os the related works.  
Our research aims to address these gaps by designing a decentralized identity management framework that integrates the IOTA Identity, Streams, and Stronghold technologies. By focusing on resource-constrained IoT environments, this study builds on existing work and demonstrates the feasibility of leveraging the IOTA architecture to achieve secure, scalable, and privacy-preserving identity solutions. Through a proof-of-concept implementation, we validate the performance and practicality of this approach, contributing to the broader discourse on decentralized identity in the IoT.  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline
**Topic** & **Paper** & **Limitations** & **Contributions** \\ \hline Blockchain-based & [13] & Clear registration processes for IoT devices are difficult to establish due to the increasing number and variety of devices. Centralized IoT platforms impede peer-to-peer data exchange while ensuring device security during ownership transitions is vital for effective identity management. & A semi-decentralized Blockchain-based identity management framework for IoT ensures unique device identification, clear registration, and global identity maintenance. It uses smart contracts for secure identity creation, transfer, and verification, enhancing security and traceability. & Digital identity challenges for IoT, including scalability, security, and privacy, are explored. Blockchain-based sovereign identity solutions and IoT identity projects are surveyed, highlighting issues such as access control, privacy, and performance, along with future research directions. & The paper proposes a “Task Structure-Technological Properties-Fit’ framework for decentralized identity management (DIdM), offering a comprehensive review of key task goals, stakeholder values, and DIdM properties and highlighting the importance of aligning these factors to facilitate DIdM adoption and use. \\ \hline \end{tabular}
\end{table}
Table 1: Summary of the related works in the literature.