ITU‐T's Technical Reports and Specifications 441 o Similarly, information on critical infrastructure like smart grids is highly sensitive, and if compromised or in the wrong hands, could endanger national security and economic interests. o Identity theft, counterfeiting and forgery are other instances of data‐related threats that could aim at different sorts of fraud, e.g. card cloning or license plate counterfeit. Data availability issues o A vast number of RFID and other IoT devices in SSC will involve potential issues with the traditional authentication systems. The massive presence of strict certification requirements can cause a severe impact on system efficiency, for example, when cross‐domain access is needed, involving authentication systems. 7 Security architecture of SSC An information security system provides a security guard for a smart sustainable city both in terms of technology and management aspects. A sample architecture is presented in Figure 2, and includes the following main components: information security infrastructure; information security mechanism: – information security management system; – information security technical protection; – information security operation and maintenance system; security of applications (top section of Figure 2). The information security infrastructure can include several centers, such as the security management center, the key management center and the identity management center. A comprehensive security strategy should address the security risk at each of these layers (i.e. sensing layer, communication layer, data layer and application layer), in order to ensure a system‐wide, all‐encompassing protection for SSC from the multiple threats that can affect the optimal operation of its services. This protection mechanism should also cover the various applications implemented in SSC (e.g. medical, traffic, travel).