Research On Theory And Applications Of Digital Signature

The information security has become more and more crucial with the development of computer and network technologies. Compared with other technologies in information security, the digtal signature is important especially in the authentication, data integrity, and non-repudiation. It has been widely used in military, communication, e-commerce and e-government, etc. The main interest of this dissertation is on the theory and method of digital signature and its application. The research focuses on some key problems of digital signature schemes, such as threshold signature, group signature, ring signature and XML signature. These are studied on the basis of many research works of a lot of academicians and experts, and some new digital signature schemes are proposed.In the researches of threshold signature, the main work is as follows: (1) A new threshold signature scheme without a trusted center is proposed. Different from previous schemes based on discrete logarithm, the proposed scheme is on the basis of Boneh et al.'s scheme for efficient generation of shared RSA keys and Shamir's perfect secret sharing scheme. (2) In order to distribute the power of verifying the signature of a message, a new threshold shared verification signature scheme with specified receiving groups is proposed. The scheme is on the basis of Shamir's threshold secret sharing scheme and a modified RSA signature scheme. It avoids the problem of calculating reverses for arbitrary elements in structures and both the computational efforts and communication costs of it are small. (3) By extending the threshold shared verification signature scheme, a new generalized shared verification signature scheme with specified receiving groups is proposed. The scheme builds on a modified ElGamal digital signature scheme and Brickell's vector space secret sharing scheme and is secure and efficient.In the researches of the group signature, to avoid the shortcomings of several previous threshold group signature schemes, a novel robust coalition-resistant (t, n) threshold signature scheme with anonymous signers is proposed. The scheme is on the basis of a modified RSA digital signature scheme. The designated signature combiner can verify the individual signature from the auxiliary value of the individual signature, and the scheme can resist the coalition attack from more than t malicious group members due to the use of shadow indivudual signature. Moreover, a distributed signature scheme for authorized subsets in a group is proposed. Arbitrary authorized subsets can sign message on behalf of the group, while any other subsets cannot sign message on behalf of the group. The individual signature combiner can easily verify the individual signatures issued by the group members, and the validity of the group signature can also be checked easily.In the researches of the ring signature, a new ring signature scheme for authorized subsets of a group is proposed by extending the ring signature scheme for individual person. In the scheme, the members of signing subset firstly construct a group including themselves, then construct a set of subsets including the signing subset, namely the authorized subsets. The signature is generated by co-operation of all members of the signing subset. The verifier can verify whether the signature is generated by one of the authorized subsets, but s/he cannot find out the detailed signing subset. The scheme is proved secure under the random oracle model.In the researches of web services and XML signature, the architechure of the web service is analyzed. And a UML-based method for XML schema design and a translation method from relational schema to XML schema are proposed respectively. After that, the specification of XML digital signature is analyzed and is contrasted by the traditional signature. In the end, an authorized subsets oriented ring XML signature scheme is proposed and the corresponding processes of sign and verification are also given.