## 3 NDN Enabled Communication and Transport Research in V2X
### Security, Authenticity and Integrity  
The concept of security is inherent to ICN and its implementations like NDN. That is because the location independence of data. If data is cached on its path to the consumer on untrusted nodes in the network, the actual data has to be protected. Security. Basically, NDN's security builds upon public-key cryptography [28] and relies on security bootstrapping (exchanging public keys). However, this concept has one crucial issue, namely caching (which is a major advantage of NDN). Using traditional public-key cryptography enforces that content chunks are encrypted for each consumer which obviously leads to a bad cache hit ratio [29]. The approach of clustering consumers and using re-encryption proxies, provides a feasible solution from a caching point of view but raises the problem of required processing resources of those re-encryption proxies. Another approach is to use Broadcast Encryption which provides a better cache affinity. The work of [PERSON] et al. [29] provides an investigation of Broadcast Encryption applied to multimedia (video and audio) streaming. Authenticity. Again, a public-key infrastructure can be utilized to provide/issue certificates through a trusted instance. The content producer signs the data chunks and the consumer can easily verify whether the received data is authentic (in the sense of generated by the (real) content origin) [28]. This is easily implementable for V2X scenarios with base stations. Vehicles will regularly pass by base stations and retrieve the necessary certificates. NDN inherently supports the possibility to schematize trust. The possibility of abstract validation based on the structure of the namespace allows applications to define rules for trust or adopt pre-defined templates (provided by experts). Furthermore, the name structure of NDN allows to bundle keys, i.e., /example/KEY/ter-3 which is the _trust anchor_ refers via a given policy to intermediate keys, i.e., /example/user/KEY/ter-4 (providing a trust hierarchy). Currently, one of the biggest problems for a real deployment of ICN (and its implementation NDN) is content poisoning. Here, a content (not the real origin) provider issues malicious content under the same name as another registered provider. The content may be signed with a faked signature, or not signed at all (just padded with random bits). The problem of content poisoning originates in the circumstance that routers do not have the resources to verify each (Data) packet. An in-depth analysis and investigation on the impact of content poisoning attacks in NDN is given in [30]. The authors also address the drawbacks of current solutions to content poisoning attacks which involve verification of content in intermediate routers (i.e., [31]). The root cause of content poisoning is _prefix hijacking_[32]. In order to tackle this attack vector, [PERSON] et al. [33] introduce and investigate the _prefix attestation protocol_ which builds on top of tracing-based mobility protocols [34]. The results indicate that their solution based on hash-chaining is order of magnitudes better than signature verification but introduces the possibility of denial of service attacks exploiting the introduced protocol. Despite of recent efforts, there currently exists no practically feasible solution to these problems. Integrity. Data integrity can be interpreted in many different ways depending on the application area. Generally speaking, integrity guarantees that data is reliable, accurate and consistent. In V2X scenarios data integrity of transmitted sensor data is essential. e.g., if an autonomously driving vehicle trusts sensor data from another vehicle, the consequences of unreliable, inaccurate, or inconsistent data may be tremendous. The importance of data integrity for autonomously driving vehicles and in general V2X scenarios, as well as how integrity can be verified by internal (i.e., sensors) and external (i.e., map data) means is briefly discussed in [35].