A survey on the provable security using indistinguishability notion on cryptographic encryption schemes

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Matematik Bölümü, Türkiye

Tezin Onay Tarihi: 2018

Öğrenci: EMRE AYAR

Danışman: ALİ DOĞANAKSOY

Özet:

For an encryption scheme, instead of Shannon's perfect security definition, Goldwasser and Micali defined a realistic provable security called semantic security. Using indistinguishability notion, one can define security levels according to the polynomial time adversaries' capabilities such as chosen plaintext attacks (CPA) and chosen ciphertext attacks (CCA) for both symmetric and asymmetric encryption schemes in addition to the hard mathematical problems the algorithms based on. Precautions to prevent these attacks, however, differ for symmetric and asymmetric schemes in some aspects. In a symmetric encryption scheme, designer needs to impose a secure mode of operation to the cipher whereas in asymmetric encryption schemes padding and hash- based structures are used to provide security. In this thesis, we first give the descriptions of CPA and CCA security under indistinguishability notion for both symmetric and asymmetric encryption schemes. Then we analyse the security of widely used algorithms with respect to these security models. .