Hiyerarşik Asıllamalı Veri Yapılarıla Güvenilebilir Bulut Hizmetleri

As the hardware and smart mobile devices progress and Internet becomes pervasive, new sets of IT services appear. These services are fed in by data and generate new data as output. Therefore, more and more data is generated and used by enterprises and individuals which confirms the important role of data. Data is the most valuable asset of this era. There are several threats targeting data, ranging from natural disasters such as fire and flood to computer viruses and crashes, and from untrusted employees having access to data to outside adversaries. Cloud storage offers a trusted platform to host others' data, and brings advantages such as cost saving, global access to data, and reduced management overhead, while posing some disadvantages: The data owner looses the direct control over her data, and some other unauthorized people gain access to the data. This thesis targets providing reliable cloud storage services. The reliability is used here for different security properties. It includes availability which means that the client can access her data at any time and any location. We propose a scheme that supports availability through distribution and replication, while improving search and update time considerably. Moreover, we propose a generic framework for constructing proof of retrievability schemes that aim achieving availability through employing erasure-correcting codes. It also encompasses data integrity which means that the cloud service provider gives a cryptographic proof along with each answer he sends to the client, enabling her to check correctness of the answer. Our schemes provide integrity in the presence of malicious adversaries. We also investigate database outsourcing and its security requirements (in a unified security definition): completeness, correctness, and freshness. Moreover, it comprises data confidentiality, which gives the assurance that no one except those who were determined by the client already, can access the data. We propose a searchable symmetric encryption scheme that supports both confidentiality and integrity for dynamic data in malicious settings.