Practical application of distributed ledger technology in support of digital evidence integrity verification processes

After its birth in cryptocurrencies, distributed ledger (blockchain) technology rapidly grew in popularity in other technology domains. Alternative applications of this technology range from digitizing the bank guarantees process for commercial property leases (Anz and IBM, 2017) to tracking the provenance of high-value physical goods (Everledger Ltd., 2017). As a whole, distributed ledger technology has acted as a catalyst to the rise of many innovative alternative solutions to existing problems, mostly associated with trust and integrity. In this research, a niche application of this technology is proposed for use in digital forensics by providing a mechanism for the transparent and irrefutable verification of digital evidence, ensuring its integrity as established blockchains serve as an ideal mechanism to store and validate arbitrary data against. Evaluation and identification of candidate technologies in this domain is based on a set of requirements derived from previous work in this field (Weilbach, 2014). OpenTimestamps (Todd, 2016b) is chosen as the foundation of further work for its robust architecture, transparent nature and multi-platform support. A robust evaluation and discussion of OpenTimestamps is performed to reinforce why it can be trusted as an implementation and protocol. An implementation of OpenTimestamps is designed for the popular open source forensic tool, Autopsy, and an Autopsy module is subsequently developed and released to the public. OpenTimestamps is tested at scale and found to have insignificant error rates for the verification of timestamps. Through practical implementation and extensive testing, it is shown that OpenTimestamps has the potential to significantly advance the practice of digital evidence integrity verification. A conclusion is reached by discussing some of the limitations of OpenTimestamps in terms of accuracy and error rates. It is shown that although OpenTimestamps has very specific timing claims in the attestation, with a near zero error rate, the actual attestation is truly accurate to within a day. This is followed by proposing potential avenues for future work

Development of an Integrative Structure for Discrete Event Simulation, Object Oriented Modeling and Embedded Decision Procession

Industrial Engineering and Managemen

Analysis of the recruitment of the class I myosin Myo5p to endocytic sites in Saccharomyces cerevisiae

In Saccharomyces cerevisiae, dynamic complexes of multiple proteins that assemble in cortical patches at the plasma membrane have been identified as sites of endocytosis. During endocytic vesicle formation, proteins associate and dissociate at these membrane subdomains in a highly defined temporal order. The type I myosin Myo5p is an essential component of the endocytic machinery of S. cerevisiae. The protein has been shown to be localized to the cortical patches in a short time interval, preceding vesicle scission from the plasma membrane. In the present work, we analyze the process of Myo5p recruitment to the endocytic patch. To investigate which domains are required for targeting of the myosin, we used GFP-tagged Myo5p mutants and life cell imaging. Starting with these experiments, we demonstrate the existence of an inhibitory interaction between the Myo5p tail homology 1 (TH1) domain and the most C-terminal portion of the myosin, which includes the SH3 domain. Such interaction precludes the SH3-mediated Myo5p association with Verprolin and Myo5p recruitment to the cortical patch. Using different kinds of experiments, we find strong evidence that the interaction between the Myo5p TH1 domain and the C-terminus is released at the plasma membrane by dissociation of calmodulin from the Myo5p neck domain, which lies immediately upstream of the TH1 domain. Further, we find that calmodulin release increases the affinity of the Myo5p neck and TH1 domains for acidic phospholipids. Based on our results, we propose a model for calmodulin-regulated patch recruitment of Myo5p, whereby calmodulin dissociation from the Myo5p neck at the plasma membrane releases an intramolecular interaction between the Myo5p TH1 domain and the C-terminus, allowing the association of the Myo5p SH3 domain with Verprolin and the interaction of the Myo5p neck and TH1 domains with acidic phospholipids

Runtime Adaptation of Scientific Service Workflows

Software landscapes are rather subject to change than being complete after having been built. Changes may be caused by a modified customer behavior, the shift to new hardware resources, or otherwise changed requirements. In such situations, several challenges arise. New architectural models have to be designed and implemented, existing software has to be integrated, and, finally, the new software has to be deployed, monitored, and, where appropriate, optimized during runtime under realistic usage scenarios. All of these situations often demand manual intervention, which causes them to be error-prone. This thesis addresses these types of runtime adaptation. Based on service-oriented architectures, an environment is developed that enables the integration of existing software (i.e., the wrapping of legacy software as web services). A workflow modeling tool that aims at an easy-to-use approach by separating the role of the workflow expert and the role of the domain expert. After the development of workflows, tools that observe the executing infrastructure and perform automatic scale-in and scale-out operations are presented. Infrastructure-as-a-Service providers are used to scale the infrastructure in a transparent and cost-efficient way. The deployment of necessary middleware tools is automatically done. The use of a distributed infrastructure can lead to communication problems. In order to keep workflows robust, these exceptional cases need to treated. But, in this way, the process logic of a workflow gets mixed up and bloated with infrastructural details, which yields an increase in its complexity. In this work, a module is presented that can deal automatically with infrastructural faults and that thereby allows to keep the separation of these two layers. When services or their components are hosted in a distributed environment, some requirements need to be addressed at each service separately. Although techniques as object-oriented programming or the usage of design patterns like the interceptor pattern ease the adaptation of service behavior or structures. Still, these methods require to modify the configuration or the implementation of each individual service. On the other side, aspect-oriented programming allows to weave functionality into existing code even without having its source. Since the functionality needs to be woven into the code, it depends on the specific implementation. In a service-oriented architecture, where the implementation of a service is unknown, this approach clearly has its limitations. The request/response aspects presented in this thesis overcome this obstacle and provide a SOA-compliant and new methods to weave functionality into the communication layer of web services. The main contributions of this thesis are the following: Shifting towards a service-oriented architecture: The generic and extensible Legacy Code Description Language and the corresponding framework allow to wrap existing software, e.g., as web services, which afterwards can be composed into a workflow by SimpleBPEL without overburdening the domain expert with technical details that are indeed handled by a workflow expert. Runtime adaption: Based on the standardized Business Process Execution Language an automatic scheduling approach is presented that monitors all used resources and is able to automatically provision new machines in case a scale-out becomes necessary. If the resource's load drops, e.g., because of less workflow executions, a scale-in is also automatically performed. The scheduling algorithm takes the data transfer between the services into account in order to prevent scheduling allocations that eventually increase the workflow's makespan due to unnecessary or disadvantageous data transfers. Furthermore, a multi-objective scheduling algorithm that is based on a genetic algorithm is able to additionally consider cost, in a way that a user can define her own preferences rising from optimized execution times of a workflow and minimized costs. Possible communication errors are automatically detected and, according to certain constraints, corrected. Adaptation of communication: The presented request/response aspects allow to weave functionality into the communication of web services. By defining a pointcut language that only relies on the exchanged documents, the implementation of services must neither be known nor be available. The weaving process itself is modeled using web services. In this way, the concept of request/response aspects is naturally embedded into a service-oriented architecture