hsm survey WIP

chapter-hsms/chapter.tex

@@ -112,9 +112,29 @@ cloning. This device will also be analyzed later in this chapter.
 
 \section{The Principles of Tamper-Sensing Mesh Construction and Monitoring}
 
-\subsection{Security Mesh Manufacturing}
+\subsection{Tamper-sensing Mesh Manufacturing}
 
-\subsection{Security Mesh Monitoring}
+The manufacturing technology of a tamper sensing mesh is a critical factor in its security. While in many applications,
+meshes manufactured from off-the-shelf processes such as Flexible Printed Circuit (FPC) processes are used, these
+processes tend to be optimzed to maximize the robustness of the produced circuits to mechanical stress. In contrast, the
+ideal tamper-sensing mesh is exactly as robust as it needs to be not to be destroyed accidentially during normal
+handling, but should not be more robust than that. As a result, more secure meshes tend to be manufactured in bespoke
+manufacturing processes.
+% FIXME cite Immler et al
+
+One more widely cited tamper-sensing mesh implementation is a commercial product developed by IBM in collaboration with
+chemical company W.\ L.\ Gore \& Asscociates Inc.\ and used in IBM's datacenter HSM products up to approximately 2020.
+% FIXME mention that Immler et al. cite them
+This mesh design uses a stack of multiple layers of a clear, flexible plastic substrate on which carbon-based traces are
+printed. Vias, i.e. contacts between layers, are made by laser cutting small holes into the substrate before the traces
+are printed. The flexible circuit layers are joined with a opaque black, stretchy glue and after installation embedded
+in an elastic opaque resin. The plastic substrate foil is thinner and significantly less resistant to tearing than
+plastic substrates commonly used in the electronics industry for applications like key pads and circuit boards, which
+improves its security against tampering. Furthermore, both the glue fusing the foil layers together and the resin the
+mesh is embedded inside after installation are clearly co-designed with the carbon trace material such that the trace
+material adheres well to both, leading to the traces being destroyed when either are peeled off.
+
+\subsection{Tamper-sensing Mesh Monitoring}
 
 \subsection{Other Tamper Sensing Techniques}
 
@@ -122,7 +142,14 @@ cloning. This device will also be analyzed later in this chapter.
 
 \subsection{The Patent Landscape}
 
-Tamper-sensing meshes can be implemented 
+Tamper-sensing meshes can be implemented in many different ways. Their design offers various degrees of freedom from the
+precise conductor layout, through the manufacturing technology of the mesh and how it is wrapped around the payload
+during manufacturing up to its monitoring circuitry. As a result, manufacturers across application domains from
+datacenter appliance HSMs through card payment terminals and including niche applications like mail franking machines
+have historically used patents on parts of their tamper-sensing mesh implementations as a means to prevent copying of
+their designs. While most original tamper sensing mesh implementations are covered by at least one patent, we want to
+highlight IBM for dwarfing the efforts of most other companies and fielding industry's widest portfolio of related
+patents.
 
 \section{A Survey of Meshes in the Wild}
 
@@ -208,7 +235,7 @@ cases.
 \subsubsection{Other miscellaneous devices}
 
 Sometimes, tamper-sensing meshes show up in other types of devices. We acquired two such devices. First, we acquired a
-Neopost franking machine, a type of device that is used to directly print a code on an envelope that replaces a
+Neopost mail franking machine, a type of device that is used to directly print a code on an envelope that replaces a
 conventional postage stamp.
 
 \section{Conclusion}

chapter-introduction/chapter.tex

@@ -190,7 +190,7 @@ In this thesis, we use the terms \emph{Tamper-Sensing Mesh} and \emph{Security M
 refer to any electrical circuit whose path is laid out to cover a surface with the intent of detecting attempts at
 drilling, cutting or otherwise manipulating this surface. While the term \emph{Security Mesh} is more concise, it is
 less clear to people unfamiliar with the matter. It is also polysemous, and depending on context can also refer to woven
-or stamped metal meshes used as fences or as screens in front of windows to prevent break-in. As a result, it is harder
+or stamped metal meshes used as fences or as screens in front of windows to prevent break-ins. As a result, it is harder
 to use in online searches, and when using Large Language Models (LLMs), it frequently leads to amusing hallucinations.
 
 %In the early days of mass-market computing, the expectations towards this new tool were high. Even before people