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Hybrid fully homomorphic framework

Abstract : Fully homomorphic encryption, firstly built in 2009, is a very powerful kind of encryption, allowing to compute any function on encrypted data, and to get an encrypted version of the result. Such encryption enables to securely delegate data to a cloud, ask for computations, recover the result, while keeping private the data during the whole process. However, today’s inefficiency of fully homomorphic encryption, and its inadequateness to the outsourcing computation context, makes its use alone insufficient for this application. Both of these issues can be circumvented, using fully homomorphic encryption in a larger framework, by combining it with a symmetric encryption scheme. This combination gives a hybrid fully homomorphic framework, designed towards efficient outsourcing computation, providing both security and privacy. In this thesis, we contribute to the study of hybridfully homomorphic framework, through the analysis, and the design of symmetric primitives making efficient this hybrid construction. Through the examination of fully homomorphic encryption schemes, we develop tools to efficiently use the homomorphic properties in a more complex framework. By investigating various symmetric encryption schemes, and buildingblocks up to the circuit level, we determine good candidates for a hybrid context. Through evaluating the security of constructions optimizing the homomorphic evaluation, we contribute to a wide study within the cryptographic Boolean functions area. More particularly, we introduce a new family of symmetric encryption schemes, with a new design, adapted to the hybrid fully homomorphic framework. We then investigate its behavior relatively to homomorphic evaluation, and we address the security of such design. Finally, particularities of this family of ciphers motivate specific cryptanalyses, therefore we develop and analyze new cryptographic Boolean criteria.
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Submitted on : Tuesday, July 17, 2018 - 12:40:18 PM
Last modification on : Friday, October 15, 2021 - 1:39:54 PM


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  • HAL Id : tel-01665358, version 2



Pierrick Méaux. Hybrid fully homomorphic framework. Cryptography and Security [cs.CR]. Université Paris sciences et lettres, 2017. English. ⟨NNT : 2017PSLEE066⟩. ⟨tel-01665358v2⟩



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