identifiers for GeoNetworking, certs and BTP

glossary.tex

@@ -6,6 +6,8 @@
 
 \acro{BTP}{Basic Transport Protocol}
 
+\acro{CA}{Certificate Authority}
+
 \acro{CCU}{communication \& control unit}
 
 \acro{ETSI}{European Telecommunications Standards Institute}
@@ -22,8 +24,12 @@
 
 \acro{LS}{GeoNetworking Location Service}
 
+\acro{LLC}{Logical Link Control}
+
 \acro{LT}{GeoNetworking Location Table}
 
+\acro{MAC}{Medium Access Control}
+
 \acro{OBU}{on-board unit}
 
 \acro{OSI}{Open Systems Interconnection}

main.tex

@@ -183,7 +183,7 @@ CALM FAST \cite{TN_libero_mab2} is a non-IP port-mapper protocol designed for si
 
 \acf{GN} (\cite{europeantelecommunicationsstandardsinstituteetsiETSI30263612014} and following) is an \ac{ETSI}-standardized networking protocol for routing and forwarding packets through \acp{VANET} based on geographical Information.  It sits between the link and network layer and provides its services to other networking and transport protocols.  The background section of \cite{sandonisVehicleInternetCommunications2016} gives a good high-level overview of the \ac{GN} networking architecture and the rationale behind it.
 
-Every \ac{GN} node has to know its geographical position, e.g. through \acp{GNSS}), for the routing to work.  The services provided by \ac{GN} are:
+Every \ac{GN} node has to know its geographical position, e.g. through \acp{GNSS}, for the routing to work.  The services provided by \ac{GN} are:
 
 \begin{itemize}
  \item geo-unicast: routing a packet to a single node at a specific location
@@ -218,16 +218,45 @@ If \ac{IPv6} over \ac{GN} is used at the network layer, transport protocols like
 
 \subsection{Identifiers}
 
-There are many different addresses, IDs or other identifying information scattered around the network layers. This sections gives a list of these identifiers and the information encoded in them.
+There are many different addresses, IDs or other identifying information scattered around the network layers. This sections gives a list of relevant identifiers and the information encoded in them. Media-dependent additional identifiers are considered out-of-scope.
 
 \subsubsection{GeoNetworking}
 
-Each \ac{GN} node is identified by a \ac{GN} address
+Each \ac{GN} node is identified by a 64bit GN\_ADDR address \cite{europeantelecommunicationsstandardsinstituteetsiETSI302636412017}, containing information about the \ac{ITS} station type (passenger car, cyclist, pedestrian, \ac{RSU}, …) and 48bit derived from the link-layer address. In case of a pseudonym change, only the latter part is supposed to change.
 
-\ac{GN} packets have a basic, a common and an optional extended header.
+\begin{figure}
+ \includegraphics[width=0.47\textwidth]{figures/GeoNetworking_structure.png}
+ \caption{structure of an unsecured \ac{GN} packet, source: \cite{hamidaSecurityCooperativeIntelligent2015}}
+ \label{fig:GNstructure}
+\end{figure}
+
+As shown in fig. \ref{fig:GNstructure}, \ac{GN} packets have a basic, a common and an optional extended header. The \textit{basic header} contains information like the packet's maximum lifetime and the remaining hop limit. These information are non-critical for identification. The \textit{common header} also doesn't contain identifying, only the flag indicating a mobile or stationary \ac{ITS} station could slightly reduce the anonymity set. The \textit{extended header} fields depend on the actual \ac{GN} package type and can contain information like the sequence number (initialized with 0) and position vectors.
+
+The \ac{LT} is populated with information from beaconing messages and all other messages received by the \ac{ITS} node.  \acl{LT} entries also contain identifying data: Additionally to the GN\_ADDR, station type and link-layer address of the peer node it contains a timestamped geographical position (including accuracy), its current speed and its heading. \todo{update position/ reacquire it when changing pseudonym}
+
+\begin{figure}
+ \includegraphics[width=0.47\textwidth]{figures/GeoNetworking_structure_secured.png}
+ \caption{structure of a secured \ac{GN} packet, source: \cite{hamidaSecurityCooperativeIntelligent2015}}
+ \label{fig:GNstructure_secured}
+\end{figure}
+
+Parts of \ac{GN} packets can be secured by wrapping them into security headers as defined in \cite{europeantelecommunicationsstandardsinstituteetsiETSITS1032017} as shown in fig. \ref{fig:GNstructure_secured}.  This service is provided by the vertical security layer in the \ac{ETSI} \ac{ITS} architecture and secures all parts shown in fig. \ref{fig:GNstructure_secured} between security header and trailer according to the chosen security profile.  The standard defines security profiles for encrypted, signed, externally signed, and signed encrypted messages. 
+
+The certificates used contain information about signer  subject (name, type, keys), validity restrictions and the actual certificate signature from the \ac{CA}.
+The signer information can be given in form of a digest, certificate or certificate chain.
+
+The security trailer contains a signature for verifying authenticity and integrity of the message. 
+
+\todo{sequence number initialized with 0}
+\todo{packet buffers: LS, forwarding}
 
 \subsubsection{BTP}
 
+The \ac{BTP} header as defined in \cite{europeantelecommunicationsstandardsinstituteetsiETSI302636512017} is only 4 bytes long and has a quite simple structure.  \\
+There are 2 modes of operation for BTP: \textit{interactive packet transport} using the BTP-A header, meant for services requiring replies to their messages, and \textit{non-interactive packet transport} using the BTP-B header.
+The BTP-A header consists out of 2 16bit numbers denoting the source and destination ports. The BTP-B header contains the 16bit long destination port and 16bit for optional destination port information (depending on the service).  
+Some of the facility layer services have well-known ports assigned in \cite{europeantelecommunicationsstandardsinstituteetsiETSITS1032016}, so the destination port might identify the service used.
+
 \section{Pseudonym Schemes}
 
 \subsection{Pseudonym Schemes for ETSI ITS Systems}

mybib.bib

@@ -447,4 +447,13 @@
   note = {http://www.rfc-editor.org/rfc/rfc4861.txt}
 }
 
+@misc{europeantelecommunicationsstandardsinstituteetsiETSITS1032016,
+  title = {{{ETSI TS}} 103 248  {{V1}}.1.1 {{Intelligent Transport Systems}} ( {{ITS}} ); {{GeoNetworking}};  {{Port Numbers}} for the {{Basic Transport Protocol}} ({{BTP}})},
+  lccn = {ETSI TS 103 248  V1.1.1},
+  author = {{European Telecommunications Standards Institute (ETSI)}},
+  month = nov,
+  year = {2016},
+  file = {/home/spiollinux/Zotero/storage/U3RMDZ2I/ts_103248v010101p.pdf}
+}
+