Research On Digital Signature Theory And Algorithm

Human beings have entered into the information era with the development of computer and network technologies; thus, the security problem of information has become the fundamental matter. The modern cryptography is the kernel technique of information security. The digital signature is one of main researches in modern cryptography, and it cannot be substituted by other techniques in information security, including authentication, data integrity, and non-repudiation. Digital signatures have many applications in military, electronic commerce and electronic government, etc.The specialized digital signature, such as multi-signature, group signature, ring signature, blind signature and proxy signature, are suitable for some special requirements in the application of digital signature. In this dissertation, the theories and algorithms of specialized digital signature are studied based on many research works of a lot of academicians and experts, and some digital signature schemes are proposed.Considering the signing order among co-signers may satisfy a special sequence and sometimes each signer can express his or her intention associating with the message to be signed and referred to by others in the application of multi-signature, the author proposes a multi-signature from bilinear pairings. The proposed scheme has two properties that it can set up the order of signing in advance and add the intention of the signer into the signature. Many of multi-signature schemes are assumed that a message is fixed beforehand, so each signer cannot modify the original message. Two multi-signature schemes with message flexibility were proposed: the one is ID-based multi-signature scheme with message flexibility, and the other is multi-signature scheme based on the ring signature with message flexibility. An anonymous appraisal protocol is designed by using the multi-signature scheme based on the ring signature.A fair group blind signature scheme is proposed. It is an extension of Lysyanskaya and Ramzan's group blind digital signature scheme by adding the fair property. Since our scheme allows the judge to find out the contents of the message and to identify the sender of the digital data, it can efficiently prevent the criminality of using the anonymous property of the blind signatures. A new dynamic group signature model is proposed recently. Based on it, a new dynamic group signature scheme from bilinear pairing is presented in this thesis that realizes the functions of the dynamic group signature model. Aring signature scheme is constructed based on bilinear maps. It has the following advantages: The manager can identify the signer from her/his signature and the tractability of the manager can be shared with others. Then we improve the Omote and Miyaji's English auction protocol by utilizing the ring signature scheme. The new English auction protocol has not the drawback that anybody can link the bids placed by the same bidder in an auction. A new forward security digital signature scheme is presented based on ElGamal digital signature, and it can efficiently against forge attack. The scheme only increases a little computation comparing with ElGamal scheme, so it is a very useful digital signature scheme. The method of forward security can also be applied to the Digital Signature Standard. Furthermore, a forward-secure threshold digital signature scheme is proposed.In this thesis, an n-times proxy signature scheme is proposed. In the scheme, an original signer can limit the times of signature using by a proxy signer. If the same proxy private key is used more than once by the proxy signer, then the secret key of proxy signer will be broken. The proxy signer could not compute the proxy signature if the using times is over n. Another proxy signature scheme is constructed in this file, it has the two properties that the original signer can set up the time limit of the proxy power holding by the proxy signer and can trace the receiver of the signature. A new proxy signature scheme based on RSA cryptosystem is also proposed. Comparing with o...