Theory And Application Study On Universally Composable Security

With the development of the Internet and E-business, the human society's reliance on the network gradually increases, such as the transaction of E-cash,E-auction,E-bidding and the subscription of E-contract. At the same time, security issues become a problem that can not be ignored. In complex and distributed network environment, a single protocol has apparently been unable to meet people's needs, and it is necessary to combine many protocols . Whether the security can be guaranteed when a secure protocol is composed with an arbitrary set of protocols, or more genernally when the protocol is used as a component of an arbitrary systems, becomes an important issue in the field of security. Canetti proposed UC security (Universally Composable Security) as an important means to solve the problem of protocol composition. In this paper, we focus on the research of UC framework theory and applications.As a method of provable security, UC framework defines a set of security model to solve the security of composed protocols in complex network environment. UC security adopts the modular idea. in the UC framework, as a module in complex network environment, the protocol proved to be UC secure, combined with other protocol, does not destroy the security of composed protocol. That is, the protocol which is composed of several separately UC secure protocols is still secure.In this paper, we mainly study on two aspects of UC security analysis: the UC theory and the applications of UC framework on secure protocols. We deeply study on the the basic UC framework of theory and its expansion, propose to analyse from the angle of the participants, design and prove an UC secure signcryption protocol.Frist of all, we summarize the development of UC framework theory, the trust assumptions and the applications in detail. A a detailed analysis of UC theory is conducted, and the critical theory - UC theorem is got. The JUC and GUC theory are also listed. In the plain model, many cryptography protocol still can not be UC securely implemented. In order to solve this problem, much idealized models have been proposed. In these models, some trust assumption is proposed, which are deeply researched in this paper.As a security model, the UC framework model is compared with the random oracle model and the standard model. In order to have a more in-depth understanding, we analyze them and try to find the intrinsic contact and difference. In addition, from the perspective of participants, the UC theory is first discussed. First, the research with the weighed parties is done. We give each party a property of weight to solve the problem when parties have different weights, especially when the adversary corrupts the parties. Secondly, from the game theory point of view, we proposed to consider the behavior of rational participants according to the benefits they get.For the important significance of UC security, it is urgently required to UC securely implement the cryptography primitive in UC framework, which can be used as a basic module in protocol compositions. Now there have been some cryptography protocol designed in UC framework and proved its security: such as encryption, digital signatures, zero-knowledge proof. In the UC frame, based on the KR Model, a signcryption protocol is discussed. According to the security requirements of signcryption protocols, the functionality is presented, and a generalizable protocol is designed. The following is the proof of UC security that is proving that the protocol securely realizes the ideal functionality. At the same time, the UC securely existential unforgeability against chosen message attacks is also discussed and is proved secure. At last, a concrete signcryption protocol is given, which is of course UC secure.