Research On Group-Oriented Digital Signature And Its Application

The last 20 years, with the universal application of computer networks and communication technology, the certification system has rapid development and has become an important research contents in cryptography. Digital signature is the most important building block in certification system, which provides important technologies such as authentication, integrity and non-repudiation, and resolved the problems of how to use electronic signatures instead of the traditional handwritten signatures and seals. With the rapid development of e-commerce and e-government, simply replacing the handwritten signature with the common digital signature can not fully meet the needs. Research on digital signature with special nature becomes an important research direction in certification theory.Group-signature and threshold-signature belong to the special group-oriented digital signature, which has a very broad application prospects in real life. Group-signature allows any members in groups can sign documents on behalf of the group, and it provides good anonymity for the group members. At the same time, if necessary, the group manager can open up the true identity of signer. Threshold signature generates the signature in a distributed way, which requires a certain number of members to cooperative to compute, so it can effectively protect the signature key to prevent abuse of sign power. The thesis studies the design and cryptanalysis of these two kinds of special signature, and also studies its application in distributed network environment. In the research of this field, the main achievements are as follows:Analyzes the formal security concept of the common digital signature and the methods of reductionist security. Proposes a probability signature based on the optimal asymmetric encryption padding (OAEP), and gives the exact security proof in the random oracle model. The work is complementarity to the research on provable security. In addition, it analyzes of the security model of signcryption, and designs an efficient signcryption scheme using the proposed signature.Discusses the theoretical model, formal security concept and a new design method of group signature. Cryptanalyzes two group-signature schemes that are insecure in design. At the same time, give the effective improvement of one of the schemes.To improve the efficiency of group-signature, design an efficient group-signature scheme for large group, which does not rely on the technology of the signature of knowledge. The scheme has a fixed length of the group public-key and group-signature, and does not need to update the group public-key key when prospective members join the group. The proposed group-signature scheme is more efficient than the current popular schemes; the open operation in the scheme is independent with the group size.Combining the advantages of identity-based cryptography system, proposes an identity-based threshold signature scheme. The scheme is robust, the size of signature does not increase with the size of group members, and the generating of signature shares is non-interactive. In all randomized RSA-based threshold signatures, it is the rare scheme that does not need synchronous network.Analyze the requirements model of secure group communication and membership control, put forward the verifiable group key management scheme (VGK) and identity based membership control scheme (IBMCS) for mobile ad hoc network. Compared with other relevant research work, the proposed schemes have better security and efficiency.Additionally, discusses some new considerations in the group-signature and threshold-signature and their applications, which will possiblly be the valuable research fields in future. So it can be referred by domestic and foreign academician.