| Cryptography can be used to meet the information confidentiality, integrity, authen-tication and non-repudiation. Traditional security analysis method of cryptographic protocols is to provide the attacker some opportunities to access the decryption ora-cle in encryption scheme or signing oracle in signature scheme, which are also called black boxes. During the process of accessing such random oracle, the attacker can only see what he chose and the corresponding output from the random oracle, but can not get any information about the secret key and secret status inside the oracle. Obvi-ously, this is an ideal security analysis method. In fact, any physical implementation of a cryptographic system will leak some information within the system. Through the various key leakage attacks, an adversary can obtain some information of the private key and the internal secret state more or less.As we all know that the public key cryptography is an important part of modern cryptography. The public key encryption technology also plays a significant role in the practical application. Therefore, the security analysis of the existing public key encryption scheme is no longer confined to the traditional idealized models. When various kinds of key leakage attacks are taken into consideration the security analysis must be changed consequentially. Due to the key leakage attack is the most important attack, considering efficient public key encryption systems with leakage resilience is just the subject of study in this thesis.The focus of this thesis is studying efficient leakage resilient encryption schemes under various public key cryptosystems. We achieve the following main results:·In the traditional public key encryption system, based on the work of leakage resilient Cramer-Shoup public key encryption scheme which Naor and Segev [93] presented in Crpyto’2009, we give a more efficient public key encryption scheme with leakage resilience compared with the CS-LR-PKE2 scheme of [93]. Our proposed scheme enjoys a low computational cost, a short key length, as well as a higher relative key leakage rate under the same CCA2security level.· In IBE cryptosystem, we get two results.-Based on Coron’s IBE scheme [29], we present a new IBE scheme with leakage resilience. Our proposed scheme is similar with the literature [28] both in efficiency and relative key leakage rate. However, in the se-curity analysis, we give two security analysis methods carefully. One is the traditional security conduction proof; the other is that if we can find an IB-HPS construction satisfying some information theoretic properties in the underlying EBE scheme, then the IBE scheme is leakage resilient [3].-We present a revocable IBE scheme with leakage resilience which can not only resist the partial leakage about the initial private key but also get the revocation functionality via public channel. And the formal secu-rity proof is given afterwards.· In CLE cryptosystem, the study of certificateless encryption with leak-age resilience is still virgin. In this thesis we supply some gaps in the following aspects.-We present the new notion and the new information theoretic properties of certificateless hash proof system for the first time. Partic-ularly in the security model of valid/invalid ciphertext indistinguishability, as distinct from traditional public key and identity-based institutions both of which have only one type of attackers, certificateless system has two different types of attackers, how to balance between these two kinds of attackers, we have done some innovation in the thesis.-We also introduce for the first time the security model and the generic construction method of certificateless leakage resilient encryption. -As a strong supporting of the new concept, we present a concrete certificateless hash proof system example. From the instantiation, we can get a certificateless encryption scheme with one-time pad genuinely.-We design a revocable CLE scheme with leakage resilience and give the security analysis thoroughly. |
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