# Decentralized Documentation of Maritime Traffic Incidents to Support Conflict Resolution
## 4 Concept
* TSA Negotiator--Responsible for the derivation of a common set of trusted TSAs between all participants. * Data Recorder--Coordinates the recording and signing of data streams by a trusted TSA derived from the TSA Negotiator. * Recording Database--Persists the original data with the associated signature from the used TSA locally. * Public Trusted Entities Repository--Can optionally be used by participants for publishing which other entities (e.g., organizations, or companies) and TSAs they trust. The repository is centrally managed and supports the participants in deriving a larger set of trusted TSAs based on their trusted relationships. Each participant deploys the _TSA Negotiator_, the _Data Recorder_, and _the Recording Database_ on its local infrastructure so that it has complete control over these components. This reduces the amount of data that leaves the infrastructure of the participant, which in turn protects the participants' sovereignty and minimizes the system's required bandwidth. In the following, the overall process of a to-be-documented situation is described in more detail:  
1. Initiate the documentation: The entire documentation process is initiated by activating a predefined trigger. This trigger can be chosen according to the use case. For instance, the trigger can be the entry of a ship into a certain geographical area (such as the port) or an under- or exceeded speed. Thus, the trigger defines whether an incident is a document worthy incident or not. The definition of a trigger is the responsibility of the participant with the primary interest in documenting a critical incident, such as the port operator, when a vessel enters the harbor. 2. Establish a communication channel: The basis for communication between the participants is a P2P-Network that is set up dynamically between the participants in  
Figure 3: Approach for Decentralized Documentation of Maritime Traffic Incidents. the event of a potential incident. By using a P2P-Network, a central communication channel can be avoided so that the participants can communicate with each other in a completely decentralized way. The network is used to coordinate the communication between the participants to agree on a common set of trusted TSAs that can then be used to sign the record. Since the negotiation already takes place during the initiation of a critical traffic situation, the involved parties must have already established a P2P network between themselves. 3. Derive a common trusted set of TSAs: After establishing a communication channel, the participants need to find a common trusted set of timestamping authorities with which they will sign their data recordings. For negotiation, each participant sends its own trusted TSAs to every other participant over the P2P network so that each participant knows the trusted TSAs from every other participant. The derivation of the trusted TSAs is performed by a deterministic negotiation protocol of the TSA Negotiator. 4. Record the data: The Data Recorder is responsible for recording and signing the data that should be documented. Therefore, the Data Recorder periodically divides the data stream from a participant into discrete chunks and sends the hashed chunks to the TSA derived by the TSA Negotiator. Afterwards, the TSA's original data and signature are stored locally in the Recording Database. In the following, we will discuss in detail how the _P2P Network_, the _TSA Negotiator_, the _Data Recorder_, and the _Public Trusted Entities Repository_ work.