# Addressing ZSM Security Issues with Blockchain Technology
## 2 Related Work
### Examining Blockchain as a Mean for the Security Enhancement in NGNs  
Authors in [27], present a combination of AI technology and DLTs in order to increase the security and trust in multi-operator mobile/cellular networks. The authors highlight the ability of AI to offer characteristics such as self-adaptation and self-reaction to next-generation networks which are susceptible to changes regarding the network conditions. This research is part of the 5 GZORRO project, and its goal is to present a conceptual architecture of a solution that uses AI and DLTs. Another work of the same project [28] proposes the use of Smart Contracts (SCs) coupled with Cloud-Native operational Data Lakes to provide a zero-touch solution for the automated service assurance of multi-domain network slices. The SLAs which define the proper performance of the services are applied in the form of Smart Contracts (SCs) deployed in a blockchain network to increase the transparency of the process and to facilitate the integrity of the agreement. This research presents an architecture for a Smart Contract-based service assurance mechanism for network slices in a multi-domain environment that is SLA-driven. Additionally, this work aims to present a definition of AI-driven SLA breach detection and mitigation mechanisms implemented as modular Cloud-native services. [PERSON] et al. [29], describe the concept of Zero Touch Networks (ZTNs) and how AI can be used to automate the service management of modern networks. However, beyond the advantages of AI-driven ZTNs, security and trust are considered open issues by the authors when AI is used. According to the authors, it has been proven that ML techniques are vulnerable to several attacks targeting both the training phase and the test phase. Since data are used by the AI mechanism, their integrity and provenance are important for the proper operation of the mechanism. Authors claim that blockchain technology can be the antidote to these security limitations, due to its immutability and distributed nature, without providing any architecture or details for the design of such a solution. In [30], the authors discuss the considerations regarding trust in modern multi-stakeholder networks and propose the use of blockchain technology to deal with trust issues. Smart Contracts (SCs) deployed in blockchain networks are ideal to create Service Level Agreements (SLAs) among stakeholders and control SLA violations in a transparent and secure manner. Based on the table presented by the authors, blockchain can be combined with many other technologies to solve trust and security issues in modern networks. Some of these technologies are VNFs, AI and ML. Moreover, sensitive data in modern networks can be protected using blockchain technology in order to guarantee their integrity and provenance. The authors discuss a use case where data are used as fuel for AI and ML focusing on the importance of data security and highlighting that data security is extremely important in AI/ML-based solutions. Data must be untampered and protected in order to avoid dataset poisoning which may lead to wrong decisions taken by the AI and ML mechanisms. In this use case, the data can be relevant to the service deployment parameters and the measured quality while blockchain technology could solve the security and trust issues. In their survey paper, [PERSON] et al. [31] present the progress of ZSM standardization and highlight the main goals and challenges. The security threats highlighted in this work by the authors are ML/AI-based attacks, open API security threats, intent-based security threats, automated Closed-Loop network-based security threats, and threats due to programmable network technologies. Moreover, the multidomain and heterogeneous nature of modern networks labels trust among different entities as a major issue. Accordingto the authors these open issues have not been sufficiently explored, although there are some published ideas where the use of blockchain is discussed as a solution.