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Research On The Anonymity Problem In The Public-key Cryptosystem

Posted on:2004-11-26Degree:DoctorType:Dissertation
Country:ChinaCandidate:J L WangFull Text:PDF
GTID:1118360122980028Subject:Cryptography
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With the ever-growing demands of various anonymous services, researches on the theory and technology of anonymity are being studied deeply. This paper aims to introduce the author's work on this area. The author is mainly focused on the study of anonymous signature, anonymous authentication, and a typical anonymous application, namely, anonymous bidding in electronic auction. The main results of this thesis are as follows:1. Based on the thoughts of "Diffie-Hellman Decision Problem" and anonymous signature, an unconditionally anonymous sign-cryption algorithm is proposed and its security proof is given.2. The problem of secure and efficient revocation of membership without incurring big costs has been considered, but no satisfactory solution was reported. Based on the ACJT group scheme, we propose a new revocation method of membership. Our solution is efficient in that it only needs one multiplication to update the public key for the group manager to exclude a group member, and the signing and verifying procedure are independent of the number of current group members and excluded group members.3. We give a new anonymous authentication scheme with identity escrow. This scheme overcomes the traditional method of using temporary public-secret keys and has the following advantages: (1) Easy for users to dynamically join and leave, which only needs the Manager to add or delete the corresponding Public Key of the user. (2) The Prover can freely choose a group of users he wants to realize his anonymous scope. (3) The right of the Manager is restricted who can only revoke the identity of the Prover with the Verifier's co-operation.4. An XTR-Ring Signature based on our new XTR-Schnorr signature is proposed, Our new XTR-Schnorr signature, with the same security and computational complexity as the known XTR-Nyber-Rueppel signature, has two advantages: 1. the, length of our signature is shorter. 2. the block cipher algorithm is not needed ; The XTR-Ring Signature algorithm is of less computational cost and shorter length than Ring Signature schemes based on RSA or DL. Also, with the fast method for computing the,trace of the elements in the finite field, two blind signature schemes based on extended XTR system are presented, the security is equivalent to solving discrete logarithm problem of extended XTR group while the datum is only as 1/3 asthat of the previous schemes.5. A Secure Sealed-bid Auction Model using only a Bit commitment protocol is proposed, and a corresponding instance is given. The model can satisfy all the secure requirements of sealed-bid auction and has the advantages: (1) the technology here used is very simple, (2) it requires almost no participation of TTP, (3) with properly one-way functions chosen, It can be exemplified into different schemes. Also, by modifying an existing first-price sealed bid scheme and combining the Bit commitment, a new secure (m+l)st-price auction scheme is proposed.6. Methods to deal with the problem of secret key compromise in cryptosystem such as Forward-secure model and Key-insulated model are surveyed. Using the idea of Secret-Sharing and Signature-of-Knowledge, a new perfect and strong Key-insulated signature scheme based on the assumption of Integer Factorization Problem is proposed. The scheme has a low computation in key updating and signing, thus fitting for the mobile devices.
Keywords/Search Tags:public-key cryptography, ring signature, group signature, anonymous authentication, unconditional anonymity, electronic auction, bidder anonymity, forward-secure signature scheme.
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