# Semantic Distributed Data for Vehicular Networks Using the Inter-Planetary File System
## 6 Security, Integrity, and Privacy  
IPFS is designed to be a secure but open network. This section describes some of the security considerations that must be applied by all participants. The main characteristic of using a P2P network is that the data are decentralized and accessible to all peers. By using IPFS, data are guaranteed to not be deleted or modified, and there is no special node or backdoor with the ability to shut down the network or delete the data. Additionally, the usage of semantic data explicitly requires that all data are understandable by any of the agents; otherwise, some nodes would have partial or incomplete information. This requirement rules out the option of using encryption or adding support for different levels of access control, as suggested in [43]. In summary, the semantic IPFS network needs to be public and freely available for easy usage to all vehicles and RSUs. Otherwise, its purpose is unaccomplished. The principles of this service could be comparable to other public and freely available services, such as OpenStreetMaps.  
Regardless of being designed as a public network, data integrity is desirable. IPFS guarantees data integrity because any content is addressed by its hash. If any node modifies the information before sending it, the receiver can detect the integrity failure by means of a quick hash function. If data source authenticity is needed, nodes could use a combination of IPNS and signed certificates. For instance, nodes could add to the content published under their IPNS addresses a link to a document listing all the previously authored content. Additionally, they could make available a certificate when a trusted certification authority (CA) signs the authenticity and veracity of the IPFS node. Note that IPNS addresses are unique, and only the original node owns the private key that allows publishing to its associated address.  
Besides integrity, a primordial aspect of an open network is to provide privacy to its participants and avoid access to sensitive data. In the IPFS network, peers need to share their IP addresses and their peer IDs, whereas MAC addresses and other low-level information are not shared. IPFS does not require nodes to use a fixed public IP address, a common privacy concern, because the discovery of other IPFS nodes is done using local multicast or broadcast protocols. The IPFS peer ID is the cryptographic identity of a particular node and it is also used as IPNS address of the peer. The ID does not contain any private information and the node chooses what sensitive details it wants to publish under its IPNS address. However, the ID is unique and unconcealed to other peers, and therefore, it is feasible to track the node activity (published and requested data). Tracking RSU activity would be easy because there are always in the same location. However, tracking a vehicle becomes challenging in a P2P network because the vehicle is constantly changing its location and connecting to different peers. In order to become impossible to track, a vehicle should avoid sharing private information and it could decide to generate a new peer ID every time that it connects to and disconnects from the network.