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Advanced Filtering of Digital Evidence
Chudáček, Ondřej ; Dzurenda, Petr (referee) ; Malina, Lukáš (advisor)
This thesis focuses on the implementation of advanced filtering of digital evidence stored on an open source cloud storage NextCloud. The contents of the thesis are law analysis regarding the storage of digital evidence in NextCloud, design of NextCloud, homomorphic encryption and its possible usages, attribute based searchable encryption and its usages and implementation of a simple stand-alone filtration client. Experts on digital evidence were asked about the choice of filtration criteria as a part of the thesis. The key feature of the thesis is a description of implementation of filtration inside NextCloud which has been extended to contain five new filtration criteria. The result has been submitted to performance and functional tests.
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Data security on operation systems
Konečný, Jakub ; Dzurenda, Petr (referee) ; Malina, Lukáš (advisor)
The bachelor thesis is focused on comparing data security options on various desktop operating systems, user authetication and provided cryptography API for developers. The thesis includes a design and realization of an application for secure data storage by using the selective database encryption.
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Privacy protection in cloud
Chernikau, Ivan ; Smékal, David (referee) ; Dzurenda, Petr (advisor)
In the Master’s thesis were described privacy protection problems while using cloud technologies. Some of the problems can be solved with help of homomorphic encryption, data splitting or searchable encryption. These techniques were described and compared by provided security, privacy protection and efficiency. The data splitting technique was chosen and implemented in the C language. Afterwards a performance of the implemented solution was compared to AES encryption/decryption performance. An application for secured data storing in cloud was designed and implemented. This application is using the implemented data splitting technique and third-party application CloudCross. The designed application provides command line interface (CLI) and graphical user interface (GUI). GUI extends the capabilities of CLI with an ability to register cloud and with an autodetection of registered clouds. The process of uploading/downloading the data to/from cloud storage is transparent and it does not overload the user with technical details of used data splitting technique.
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Group signature based on Secure Multi-party Computation
Klasovitý, Kristián ; Dzurenda, Petr (referee) ; Ricci, Sara (advisor)
Práce se věnuje implementaci skupinového podpisu, který využívá společný výpočet dvou stran k vypočítání tajné hodnoty využité k podpisu. Díky tomu zůstává soukromý klíč člena skupiny skrytý před manažerem skupiny, a nemůže být manažerem zneužit. Podpisové schéma podporuje revokaci a otevírání podpisů manažerem. Také byl představen způsob slepého vydávání atributového pověření, kde je pověření skryto před vydavatelem. Obě schémata byla spuštěna na více zařízeních a byl změřen čas jejich vykonání. Schéma pro skupinové podpisy bylo využito pro vytvoření aplikace, pomocí které je možné podepisovat dokumenty jménem skupiny. Implementace je spuštěna na více zařízeních, která komunikují pomocí NFC.
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Paillier Cryptosystem Optimisations for Homomorphic Computation.
Ryšavá, P. ; Ricci, S.
Homomorphic encryptions can ensure privacy in systems operating with sensitive data. It also allows outsourcing the data processing without the need to disclose the information within. To keep good performance over the growing mass of data, the execution of homomorphic schemes has to be efficient. In this article, we focus on the optimization of the Paillier scheme. This scheme allows the addition of a constant or another ciphertext without decryption of the encrypted values. Since the exponentiation used in the encryption process is time-consuming, we have implemented noise and message pre-computation to avoid time-demanding operations. These adjustments significantly fasten the encryption process, especially using the noise pre-computation.
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Advanced Filtering of Digital Evidence
Chudáček, Ondřej ; Dzurenda, Petr (referee) ; Malina, Lukáš (advisor)
This thesis focuses on the implementation of advanced filtering of digital evidence stored on an open source cloud storage NextCloud. The contents of the thesis are law analysis regarding the storage of digital evidence in NextCloud, design of NextCloud, homomorphic encryption and its possible usages, attribute based searchable encryption and its usages and implementation of a simple stand-alone filtration client. Experts on digital evidence were asked about the choice of filtration criteria as a part of the thesis. The key feature of the thesis is a description of implementation of filtration inside NextCloud which has been extended to contain five new filtration criteria. The result has been submitted to performance and functional tests.
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Privacy protection in cloud
Chernikau, Ivan ; Smékal, David (referee) ; Dzurenda, Petr (advisor)
In the Master’s thesis were described privacy protection problems while using cloud technologies. Some of the problems can be solved with help of homomorphic encryption, data splitting or searchable encryption. These techniques were described and compared by provided security, privacy protection and efficiency. The data splitting technique was chosen and implemented in the C language. Afterwards a performance of the implemented solution was compared to AES encryption/decryption performance. An application for secured data storing in cloud was designed and implemented. This application is using the implemented data splitting technique and third-party application CloudCross. The designed application provides command line interface (CLI) and graphical user interface (GUI). GUI extends the capabilities of CLI with an ability to register cloud and with an autodetection of registered clouds. The process of uploading/downloading the data to/from cloud storage is transparent and it does not overload the user with technical details of used data splitting technique.
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Privacy protection in cloud
Chernikau, Ivan ; Smékal, David (referee) ; Dzurenda, Petr (advisor)
In the Master’s thesis were described privacy protection problems while using cloud technologies. Some of the problems can be solved with help of homomorphic encryption, data splitting or searchable encryption. These techniques were described and compared by provided security, privacy protection and efficiency. The data splitting technique was chosen and implemented in the C language. Afterwards a performance of the implemented solution was compared to AES encryption/decryption performance. An application for secured data storing in cloud was designed and implemented. This application is using the implemented data splitting technique and third-party application CloudCross. The designed application provides command line interface (CLI) and graphical user interface (GUI). GUI extends the capabilities of CLI with an ability to register cloud and with an autodetection of registered clouds. The process of uploading/downloading the data to/from cloud storage is transparent and it does not overload the user with technical details of used data splitting technique.
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Homomorphic encryption schemes
Titěrová, Anežka ; Kazda, Alexandr (advisor) ; Hojsík, Michal (referee)
Title: Homomorphic encryption schemes Author: Anežka Titěrová Department: Department of Algebra Supervisor: RNDr. Alexandr Kazda, Department of Algebra Abstract: Rivest et al. posed in 1978 the cryptographic problem how to correctly compute arbitrary functions over encrypted data without direct decrypting. This problem is solved by using of a fully homomorphic encryp- tion scheme, which was discovered and first described by Craig Gentry in 2009. This work gives a summary of contemporary knowledge in this field. The attention will be restricted to a general overview how to construct the fully homomorphic encryption scheme with respect to the information security. The results will be applied in an implementation of a somewhat homomorphic encryption scheme as a computer program. Fully homomorphic encryption schemes have abundant applications, especi- ally in secure cloud computing. Nevertheless, the greatest challenge for scien- tists is finding out more efficient algorithm because existing implementations are not as effective and fast as required for everyday use. Keywords: homomorphic encryption, fully homomorphic encryption scheme, lattice cryptography, logic circuit
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Privacy protection in cloud
Chernikau, Ivan ; Smékal, David (referee) ; Dzurenda, Petr (advisor)
In the Master’s thesis were described privacy protection problems while using cloud technologies. Some of the problems can be solved with help of homomorphic encryption, data splitting or searchable encryption. These techniques were described and compared by provided security, privacy protection and efficiency. The data splitting technique was chosen and implemented in the C language. Afterwards a performance of the implemented solution was compared to AES encryption/decryption performance. An application for secured data storing in cloud was designed and implemented. This application is using the implemented data splitting technique and third-party application CloudCross. The designed application provides command line interface (CLI) and graphical user interface (GUI). GUI extends the capabilities of CLI with an ability to register cloud and with an autodetection of registered clouds. The process of uploading/downloading the data to/from cloud storage is transparent and it does not overload the user with technical details of used data splitting technique.
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