Christian Janson

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Publicly Verifiable Outsourced Computation (PVC) allows devices with restricted resources to delegate computations to more powerful external servers, and to verify the correctness of results. Whilst beneficial in many situations, this increases the visibility and availability of potentially sensitive data, so we may wish to limit the sets of entities that(More)
The present study was based on data from a longitudinal research program which consisted of 12,032 children, born in the Stockholm area in 1953 of which there were 494 children born with low birth weight (LBW, 2500 g or less). For all children at age 16 it was apparent that adjustment and psychiatric disturbances as well as juvenile delinquency were not(More)
Publicly Verifiable Outsourced Computation (PVC) allows weak devices to delegate computations to more powerful servers, and to verify the correctness of results. Delegation and verification rely only on public parameters, and thus PVC lends itself to large multiuser systems where entities need not be registered, yet in such settings the individual user(More)
The combination of software-as-a-service and the increasing use of mobile devices gives rise to a considerable difference in computational power between servers and clients. Thus, there is a desire for clients to outsource the evaluation of complex functions to an external server. Servers providing such a service may be rewarded per computation , and as(More)
Data loss is perceived as one of the major threats for cloud storage. Consequently, the security community developed several challenge-response protocols that allow a user to remotely verify whether an outsourced file is still intact. However, two important practical problems have not yet been considered. First, clients commonly outsource multiple files of(More)
Computing systems have been playing an important role in various medical fields, notably in image diagnosis. Highlighted among the existing exams that allow diagnostic aids and the application of computing systems in parallel is Computed Tomography (CT). This work focuses on the segmentation and reconstruction phases of CT lung images using the Adaptive(More)
When outsourcing the storage of sensitive data to an (un-trusted) remote server, a data owner may choose to encrypt the data beforehand to preserve confidentiality. However, it is then difficult to efficiently retrieve specific portions of the data as the server is unable to identify the relevant information. Searchable encryption has been well studied as a(More)
The combination of software-as-a-service and the increasing use of mobile devices gives rise to a considerable difference in computational power between servers and clients. Thus, there is a desire for clients to outsource the evaluation of complex functions to a server and to be able to verify that the resulting value is correct. Previous work in this area(More)
Acknowledgments First of all I would like to thank Prof. Dr. Michael Hortmann for supervising this thesis. I am very grateful for him introducing me to cryptography and supporting me to attend Eurocrypt 2011 and Asiacrypt 2011. I am also very thankful for Prof. Dr. Gregor Leander who took the part of being my second supervisor. I am indebted to my fellow(More)
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