# Quantum Key Distribution for 5G Networks: A Review, State of Art and Future Directions
## 2 Security Challenges in 5G Network  
Due to the global service demands the number of connected machines as mobiles, IoT, and IIoT devices, has been immensely increased. This improvement has a great impact on the regular network efficiency and capacity for that matter a 5G network technology is proposed to provide an efficient network that can cope with the recent technology revolution.  
Some of the 5G benefits is providing a quality of services based on user requirements and also 5G ensure the validity of peer-to-peer communication [12]. It promises the world with a heterogeneous network that focuses on individual reliability and integrity. Moreover, 5G proposed unlimited wireless connectivity. That depends on the high speed of data with low latency. It considers as the core foundation of the future of IA technology. Nevertheless, 5G encounter different security major issues in main security characteristics. Several of  
Figure 1: Classical QKD Mechanism (Polarization-encoding BB84 protocol).  
those vulnerabilities are in confidentiality as the risk of eavesdropping, a man in the middle, side channel, stalking attacks, other vulnerabilities affecting the availability such as jamming attacks and DDOS, DOS attacks [13]. As mentioned earlier, 5G provide a proper quality of services (QOS) for end-users. However, the primary end-user's private information such as location, personal data, activities are vague in data maintained, data storage, and the data storage conditions.  
The privacy issues in 5G can be divided into two aspects: user and network aspects. From the user aspect, end-to-end data privacy is one of the privacy issues that can evoke 5G. Since a 5G network is mostly connected to a cloud system, which supports several stakeholders in the network, such as service providers, operators, and any new technologies that are connected to business models. Most stakeholders will depend on cloud computing to store and process user's data and make the data accessible. Sharing this data between different parties can lead to privacy breaches. Thus, the end-to-end security in 5G should be handled instantly [14; 15]. Another issue is the different trust objectives between the data owner and the cloud stakeholders. This conflict can raise a different perspective on privacy. Such as losing data ownership in the 5G network, which is one of the coming issues. The 5G network provides a shared network infrastructure to run many applications together such as health care smart homes or IoT devices those shared access programs can manipulate and forge access by attackers thus 5G insecure data ownership bounders rise the chance of unauthorized access, exchange, and retrieving confidential data [16]. Another issue that is facing by 5G is the trans-border information since the global digitalization and excessive data exchange all the information will be traveled across borders as free flow this flow will be mandate based on government consent of data transfers, data storage, and data processing [17; 18].  
Meanwhile, the security issues in 5G can be divided into several key areas such as authentication, access control, communication, and encryption.