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@PHDTHESIS{Ziegeldorf:722141,
      author       = {Ziegeldorf, Jan Henrik},
      othercontributors = {Wehrle, Klaus and Scheuermann, Björn},
      title        = {{D}esigning digital services with cryptographic guarantees
                      for data security and privacy},
      volume       = {16},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Aachen},
      publisher    = {Shaker},
      reportid     = {RWTH-2018-223431},
      isbn         = {978-3-8440-5837-6},
      series       = {Reports on Communications and Distributed Systems},
      pages        = {1 Online-Ressource (276 Seiten) : Illustrationen},
      year         = {2017},
      note         = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University 2018; Dissertation, RWTH Aachen University, 2017},
      abstract     = {In the past two decades, tremendously successful digital
                      services have been built that collect, process, and monetize
                      massive amounts of personal user data, up to the point where
                      data is proclaimed the oil of the 21st century. Along come
                      serious threats to data security and privacy that
                      significantly increase the demand for effective protection,
                      e.g., as manifested in the growth of encrypted Internet
                      traffic. Communication security protocols, however, protect
                      data against external attackers and do not address the root
                      cause of almost all privacy threats, the need to share
                      sensitive data with third parties. These third parties may
                      illicitly process data beyond its original purpose of
                      collection or be hacked and forced to provide data access.
                      Countering these threats requires the development of Privacy
                      Enhancing Technologies that complement or replace
                      traditional communication security protocols. We identify
                      Secure Multiparty Computation (SMC) as a rigorous approach
                      not only to provide data security and privacy protection,
                      but even to reconcile privacy interests with seemingly
                      adverse public and business interests. However, the
                      potential of SMC is foremost on the theoretical level - it
                      is often dismissed for being too inefficient and
                      impedimentary for real-world applications. This thesis
                      bridges the gap between the theoretical strength of SMC and
                      the feeble realization of its potential in practice. To this
                      end, we conduct a qualitative and quantitative analysis of
                      SMC frameworks and abstract three research challenges: i)
                      Extending the functionality and ii) increasing the
                      efficiency of SMC as well as iii) customizing it to
                      challenged environments. We choose a use case-driven
                      research methodology to address these questions, which
                      allows us to motivate and validate all our contributions in
                      practice. First, we motivate the problem of financial
                      privacy in cryptocurrencies and propose decentralized mixing
                      as a solution. We recognize the advantages of securing
                      mixing operations with SMC and contribute secure protocols
                      to technically realize our novel approach. As a result, our
                      mixing system achieves stronger security and privacy
                      guarantees than prior works while remaining highly scalable
                      and fully compatible with the prevalent designs of
                      decentralized cryptocurrencies such as Bitcoin. Second, we
                      propose efficient SMC designs for different classification
                      algorithms to address data security and privacy issues in
                      pattern recognition and machine learning. The evaluation of
                      our classifiers shows that they are secure, accurate, and
                      outperform the state of the art. We demonstrate three
                      real-world use cases that prove applicability of our
                      classifiers but also motivate their deployment in challenged
                      environments. Thus, we present two additional approaches,
                      bandwidth optimizations and secure outsourcing, to bring our
                      secure classifiers to these scenarios. Finally, we
                      investigate secure outsourcing as a general strategy to
                      customize SMC to challenged deployment and operation
                      scenarios by the example of computing set intersections, a
                      universal building block in many real-world applications and
                      a well studied SMC problem. We present efficient schemes
                      with negligible overheads for the outsourcers and
                      demonstrate their applicability in two comprehensive case
                      studies, privacy-preserving crowd-sensing and genetic
                      disease testing in the cloud. In summary, the contributions
                      made in this thesis widen the technical solution space for
                      practical data security and privacy protection in
                      data-driven digital services.},
      cin          = {121710 / 120000},
      ddc          = {004},
      cid          = {$I:(DE-82)121710_20140620$ / $I:(DE-82)120000_20140620$},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      doi          = {10.18154/RWTH-2018-223431},
      url          = {https://publications.rwth-aachen.de/record/722141},
}