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UID:DSC-11557
DTSTART;TZID=Europe/Berlin:20160725T130000
SEQUENCE:1469433773
TRANSP:OPAQUE
DTEND;TZID=Europe/Berlin:20160725T140000
URL:https://www.dresden-science-calendar.de/calendar/de/detail/11557
LOCATION:TUD Andreas-Pfitzmann-Bau\, Nöthnitzer Straße 4601069 Dresden
SUMMARY:Roos: Analyzing and Enhancing Routing Protocols for Friend-to-Frien
 d Overlays
CLASS:PUBLIC
DESCRIPTION:Speaker: Dipl.-Math. Stefanie Roos\nInstitute of Speaker: Insti
 tut für Systemarchitektur\, Datenschutz und Datensicherheit\nTopics:\nInf
 ormatik\n Location:\n  Name: TUD Andreas-Pfitzmann-Bau (APB 1004 (Ratssaal
 ))\n  Street: Nöthnitzer Straße 46\n  City: 01069 Dresden\n  Phone: \n  
 Fax: \nDescription: The threat of surveillance by governmental and industr
 ial parties is more eminent than ever. As communication moves into the dig
 ital domain\, the advances in automatic assessment and interpretation of e
 normous amounts of data enable tracking of millions of people\, recording 
 and monitoring their private life with an unprecedented accurateness. The 
 knowledge of such an all-encompassing loss of privacy affects the behavior
  of individuals\, inducing various degrees of (self-)censorship and anxiet
 y. Furthermore\, the monopoly of a few large-scale organizations on digita
 l communication enables global censorship and manipulation of public opini
 on. Thus\, the current situation undermines the freedom of speech to a det
 rimental degree and threatens the foundations of modern society. Anonymous
  and censorship-resistant communication systems are hence of utmost import
 ance to circumvent constant surveillance. However\, existing systems are h
 ighly vulnerable to infiltration and sabotage. In particular\, emph{Sybil 
 attacks}\, i.e.\, powerful parties inserting a large number of fake identi
 ties into the system\, enable malicious parties to observe and possibly ma
 nipulate a large fraction of the communication within the system. Friend-t
 o-friend (F2F) overlays\, which restrict direct communication to parties s
 haring a real-world trust relationship\, are a promising countermeasure to
  Sybil attacks\, since the requirement of establishing real-world trust in
 creases the cost of infiltration drastically. Yet\, existing F2F overlays 
 suffer from a low performance\, are vulnerable to denial-of-service attack
 s\, or fail to provide anonymity. Our first contribution in this thesis is
  concerned with an in-depth analysis of the concepts underlying the design
  of state-of-the-art F2F overlays. In the course of this analysis\, we fir
 st extend the existing evaluation methods considerably\, hence providing t
 ools for both our and future research in the area of F2F overlays and dist
 ributed systems in general. Based on the novel methodology\, we prove that
  existing approaches are inherently unable to offer acceptable delays with
 out either requiring exhaustive maintenance costs or enabling denial-of-se
 rvice attacks and de-anonymization. Consequentially\, our second contribut
 ion lies in the design and evaluation of a novel concept for F2F overlays 
 based on insights of the prior in-depth analysis. Our previous analysis ha
 s revealed that greedy embeddings allow highly efficient communication in 
 arbitrary connectivity-restricted overlays by addressing participants thro
 ugh coordinates and adapting these coordinates to the overlay structure. H
 owever\, greedy embeddings in their original form reveal the identity of t
 he communicating parties and fail to provide the necessary resilience in t
 he presence of dynamic and possibly malicious users. Therefore\, we presen
 t a privacy-preserving communication protocol for greedy embeddings based 
 on anonymous return addresses rather than identifying node coordinates. Fu
 rthermore\, we enhance the communication's robustness and attack-resistanc
 e by using multiple parallel embeddings and alternative algorithms for mes
 sage delivery. We show that our approach achieves a low communication comp
 lexity. By replacing the coordinates with anonymous addresses\, we further
 more provably achieve anonymity in the form of plausible deniability again
 st an internal local adversary. %\, consisting of the complexity of the me
 ssage delivery in addition to the complexity of maintaining uptodate coord
 inates. Complementary\, our simulation study on real-world data indicates 
 that our approach is highly efficient and effectively mitigates the impact
  of failures as well as powerful denial-of-service attacks. Our fundamenta
 l results open new possibilities for anonymous and censorship-resistant ap
 plications.
DTSTAMP:20260522T200104Z
CREATED:20160711T075129Z
LAST-MODIFIED:20160725T080253Z
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