# Addressing ZSM Security Issues with Blockchain Technology
## 5 Criteria for the Selection of the Blockchain/DLT Platform to Build the ZSM-Tailored Solution
This results in the growth of the network as new NPs with new nodes can easily become part of the solution. As a result, the scalability feature of the entire solution is highlighted, which is a factor that attracts new members. Crash fault tolerance: the network should support fault-tolerant mechanisms in order to ensure that its operation is not affected if a number of nodes become unavailable. Considering that the ZSM framework uses the DLT network to perform crucial tasks, the resiliency of the network is vital in our scenario. The main element that is responsible for the network's proper operation is the consensus. Therefore, the network should be able to use consensus mechanisms that will increase its fault tolerance and guarantee the functionality of the system in hazardous situations. Low consensus convergence time: the proposed solution is expected to receive a large number of transactions which must be validated/executed with the minimum possible delay. As a result, the selection of a consensus algorithm with a low convergence time that is able to cope with a high number of transactions is crucial. This characteristic is related to the previous one, as the consensus mechanism used is able to increase the resiliency of the network and the speed of transaction validation. Therefore, the DLT solution should be able to support a consensus mechanism that can validate transactions fast, and at the same time tolerate failures. Support of SCs: the development of code in DLTs can be accomplished by the creation of SCs that can implement various functionalities of the network in a secure manner. Since the network should interact with ZSM services and provide solutions to many different problems regarding the management of modern networks, the capability of the DLT to support SCs is extremely important. Support of tokens: this feature is related to the previous one and highlights the need to support tokens implemented in the form of special SC functions, which improve the functionality of the solution. Tokens can be used to represent assets, currency and rights (i.e., use a token to access a website). The development of tokens is based on standards that ensure their smooth integration into the network. There are two main well-known token categories, Fungible Tokens (ERC 20) and Non-Fungible Tokens(ERC 721). In our use case, a Fungible token could be used to create a currency used for the transactions among NPs in order to build a modern marketplace. Additionally, Non-Fungible Tokens (NFTs) could be developed to represent the reputation of an NP which could be related to the successful completion of a number of requests. This feature could be used by NPs as a criterion during the process of NP selection to support their request. It should be mentioned that these scenarios are only examples of how tokens could be used and have not yet been designed for our use case. However, the ability of a network to accept and use new programming features to enhance its functionality and solve any future issues is a very important characteristic. * Interaction with oracle mechanisms: the DLT solution should be able to interact with entities outside the network in a secure manner to leverage the functionality of the whole system and support the ZSM processes. To this end, oracle mechanisms must be supported by the network, while the selection of the most suitable solution should be made based on the security level and performance. On the one hand, the information from and towards the network should be well protected while on the other hand, the latency introduced by the oracle should be the minimum. Having in mind that some oracle solutions use consensus, which automatically introduces extra latency to the system, the selection of other oracles that use different tools seems to be preferred. There are many oracle mechanisms available that use encryption to protect the content of their data and guarantee the origin of the information. The adoption of such a solution may not affect the overall system's performance dramatically.