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Doktorsvörn í tölvunarfræði: Kristján Valur Jónsson

  • 13.12.2012, 10:00 - 11:00

Kristjan

Fimmtudaginn 13. desember mun Kristján Valur Jónsson verja doktorsritgerð sína, sem ber heitið "The Security Properties of In-network Aggregation" við tölvunarfræðideild Háskólans í Reykjavík.  

Kristján hefur stundað doktorsnám við deildina síðan haustið 2008 en hluti af námi hans hefur einnig farið fram við KTH.  Á þessum tíma hefur hann birt fjölda greina á alþjóðlegum vettvangi með leiðbeinanda sínum og öðrum og var ein þessarra greina valin ein af þremur bestu greinum nemenda á ráðstefnunni Sensors Applications Symposium á þessu ári.

Kristján er fjórði nemandinn til að verja doktorsritgerð við deildina en námið hlaut viðurkenningu Mennta- og menningarmálaráðuneytis árið 2008.  Í viðurkenningarskýrslu, sem unnin var af nefnd erlendra sérfræðinga, sagði m.a. að deildin væri sterkasta tölvunarfræðideild landsins og að rannsóknir við deildina stæðu jafnfætis því sem gerðist í framsæknum stofnunum erlendis. 

Fyrirlestur Kristjáns er öllum opinn en í kjölfar hans fer fram lokuð vörn með leiðbeinanda, doktorsnefnd og prófdómara.


PhD Candidate:

Kristján Valur Jónsson

Thesis Title: The Security Properties of In-network Aggregation
Time: 10:00, on the 13th of December
Location: Room V102

Supervisor: Ýmir Vigfússon
Committee Members:
Mads F. Dam (KTH), Magnús Már Halldórsson (HR)
Examiner: Philippe Bonnet (IT Univ. of Copenhagen)

Abstract:
In-network aggregation is an important paradigm for current and future networked applications, enabling efficient cooperate processing of aggregate information, while providing sub-linear scalability properties. However, security of this important class of algorithms has to date not been sufficiently addressed.

In this dissertation, we focus on the integrity properties of in-network aggregation algorithms, in terms of the sub-goals of completeness and correctness, and discuss means by which existing algorithms can be retrofitted to provide acceptable integrity guarantees. We propose an efficient solution, which provides acceptable correctness guarantees, by ensuring individual node integrity a priori by applying the principles of trusted systems. To this end, we propose dedicated trusted sensor and aggregator modules, which are guaranteed to perform their assigned functionality correctly. Trusted modules, in conjunction with cryptographic authentication and transport protocols, can be applied to construct trusted aggregation overlays, giving strong guarantees in terms of correctness. We support our findings by a proof-of-concept prototype in a single aggregator model, as well as a design for a hierarchical in-network aggregation system.

Completeness is a more elusive goal than correctness, if only for the fact that drops and message corruptions are a fact of life in distributed systems. Hence, it may not be possible to distinguish between benign and malicious losses. Building on the trusted systems solution for correctness, we suggest a protocol which decreases the adversarial influence in a tree-based aggregation network. We exploit the fact that a secure protocol can be executed over a trusted overlay, enabling per-edge fault detection and dissemination of edge ratings. Simulation-based trials suggest that the presented protocol achieves significant reduction in the potential impact an adversary can have on the completeness of aggregate results.