Theory Study For Ring Digital Signature And Its Applications

Digital signature is the research focus of current information security field which is a technique with the function of information integrality authentication, recognizability, undeniability and encryption. Among these, there is a class of signatures we call group-oriented digital signatures. In their cryptography, the sign entity is a group in which the relationships between members are coequal or have complex structure and form. Group-oriented digital signatures have many different classes, including group signature, ring signature, threshold signature, etc. And ring signature is the main focus in this paper.Ring signature scheme enables a signer to sign on behalf of a group of n different members without their permissions and even knows such that the verifier can only ensure someone in the group signed, but not exactly whom. Ring signature can be regarded as a simplified group-like signature, which conquers the disadvantage that the group manger has oversize privilege in group signature scheme and enables its real signer have unconditional anonymity. Attributed to its own quality, ring signatures can be widely utilized in many security applications, such as anonymous electronic voting, electronic cash, electronic government, key distribution and secure multi-party computation. So it is one of recent research points.This paper summarizes systemically the research results and the development state of ring signatures based on our deep study on the existing schemes. It presents detailedly the concept of ring signature, classifys ring signatures according to the development process, presents simply its utilizations in security applications, analyzes the characteristic of the existing ring signature schemes, investigates the design philosophy behind these schemes, and describes some security models they satisfy and points out some limitations of the existing schemes.Then, the paper devotes its attention to threshold ring signature which is one of research directions of ring signature and has many application backgrounds. One contribution is to extend the scheme Shacham and Waters [38] proposed, and provide an ID-based threshold ring signature scheme with strict formal security proofs in standard model.This paper focuses on the research of solving the drawback of ring signature that is the size of ring signature is in proportion to the size of ring, which it utilizes the accumulator this time. An accumulator scheme, introduced by Benaloh and de Mare [9], allows aggregation of a large set of inputs into one constant-size value. Therefore, it can be used to construct the constant-size ring signature schemes. It makes use of the efficient dynamic accumulator Nguyen [36] proposed and constructs an efficient, constant-size ID-based ring signature scheme with strict formal security proofs. Followed this, using the above ring signature scheme and with the help of anonymity and spontaneity of it, the paper describes an efficient concurrent signature scheme which provides efficient solution to multi fair exchange problem appeared in the real fair shake. This scheme is the application example of our constant-size ID-based ring signature scheme.In the end, it summarizes some problems in ring signature research field and fingers out the possible study and evolution directions of the ring signature in future.