## 4 Technology
### Security
* Availability against DoS/DDoS attacks: data availability is a key aspect in smart grids because it can lead to financial and legal implications [PERSON] _et al._ (2013). Price data availability is critical because outdated data can affect the energy demand. Commands availability is important for economic aspects related to billing, and the availability of meter data does not represent a critical issue because the data can be read at a later point. Table 1 summarizes the levels of importance for the security properties in smart grid environments. The main entry points in a smart grid are:  
* infiltration through infected devices, _i.e._, USB sticks. * network-based intrusion, _i.e._, misconfigured or poorly configured firewalls. Backdoors and holes in network perimeter may be caused by components of the IT infrastructure that can be exploited for bypassing the access control mechanisms. When an attacker enters the trusted network, he/she can compromise some devices. Another issue can be provoked by a malicious insider (someone who is authorized to access the system) whose actions, listed in Table 2, can be difficult to detect or prevent. Countermeasures needed to avoid attacks on smart grids range from key management to network communications and system security. We report some examples below according to [PERSON] _et al_. [29]:  
* Key management is fundamental for information security: shared secret keys and authentic public keys ensure secrecy and authenticity if used properly. The key setup in this kind of solutions is the root of trust. * Secure Communication Architecture has some critical aspect such as the network topology design in order to make nodes highly resilient under attack; Secure Routing Protocol, which must be on top of the network topology; Secure Broadcasting that is typically used in smart grid environments; DoS defense to avoid an interruption of the data flow; Jamming detection mechanism can be used to detect attacks and trigger security procedures. * System and devices security has mainly to deal with software-based attacks and these techniques must prevent the injection of malicious code into the system. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Price Information** & **Control Command** & **Meter Data** & **Software** \\ \hline Confidentiality & Low & Low & Medium & Low \\ Integrity & High & High & High & High \\ Availability & High & High & Low & N/A \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Importance of security properties in smart grid environments. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Price Information** & **Control Command** & **Meter Data** & **Software** \\ \hline Confidentiality & Leakage of & Exposure of & Unauthorized access & Theft of proprietary \\ price info & control structure & to meter data & software \\ \hline Integrity & Incorrect & Changes of & Incorrect & Malicious \\ price info & control commands & meter data & software \\ \hline Availability & Unavailability of & Inability to & Unavailability of & \\ price info & control grid & billing info & N/A \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Threat Type classification based on Security Properties. In literature, some projects related to cyber security can be found, focused on different aspects of a smart grid. [PERSON] _et al_. [31] presented a security framework for smart grids, which exploits the layered architecture. This solution, scalable and distributed, integrates security at agents level, switches level, and management level, to prevent both internal and external network attacks. [PERSON] _et al_. [32] used Adapted Autonomy and Human-Automation interaction theories to create cyber security strategies for the smart grid. [PERSON] _et al_. introduced some variations in smart meter firmware [33] to avoid common vulnerabilities. [PERSON] _et al_. proposed Attestation techniques based on hardware approaches [34; 35]. [PERSON] _et al_.