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2011 : Validation Middleware for Mixed Criticality Networks

Author(s)
Thomas Mair
Abstract
This thesis investigates on the secure sharing of information in a mixed-criticality system. Our approach to fulfil these safety and security requirements in such a system is to establish a set of strict rules for the communication between the tasks of the different integrity levels. These rules implement an integrity model and have to guarantee that the information flow between the criticality levels happens appropriately. In many applications it also might be required to use a piece of unreliable information from a low criticality level in a higher one. Communication in this direction is considered as illegal in many integrity models. Therefore a special mechanism is needed to upgrade the integrity of the data. This thesis introduces a mechanism called "Validation Middleware" which upgrades the reliability of data from diverse redundant sources. To achieve this goal, inexact voting techniques are realised which produce a trusted output and define a criteria for determining correct and incorrect from data which is not necessarily identical. These mechanisms were developed and studied in context of the Time-Triggered System-On-Chip architecture. This architecture provides a spatial and temporal firewall between each task by partitioning the system into single autonomous subsystems called the micro components. These subsystems are connected through a deterministic Network-on-Chip which uses so-called encapsulated communication channels to prevent the messages from interfering with each other. These encapsulated communication channels transport messages at a predefined point in time from a single source to one or more destinations. We tested the fault tolerance mechanisms inside the “Validation Middleware“ by creating an application from the automotive context which compasses ABS and odometer subsystems. Our results show that the deterministic behaviour of the Network-on-Chip and the temporal and spatial partitioning of the encapsulated communication channels, combined with the use of Totel’s integrity policies, provides a suitable environment for the use in a mixed-criticality application. In addition, we point out the existence of a middleware in the Time-Triggered System-on-Chip architecture which enables upstream communication flows.
Bibtex
@mastersthesis{ mair:2011,
  author =      "Thomas Mair",
  title =       "Validation Middleware for Mixed Criticality Networks",
  address =     "Treitlstr. 3/3/182-1, 1040 Vienna, Austria",
  school =      "Technische Universit{\"a}t Wien, Institut f{\"u}r Technische Informatik",
  year =        "2011"
}
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