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The Research Of (t,n) Threshold Proxy Signature Based On Elliptic Curve Cryptosystem

Posted on:2012-01-25Degree:MasterType:Thesis
Country:ChinaCandidate:L X GongFull Text:PDF
GTID:2218330338467181Subject:Cryptography
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Digital signature has important applications of identity verification, data integrity checking, non-repudiation and undeniability as one of the important tool for imformation security. Proxy signature has transferred the right of the signature, and it has broad application prospects in real life. Threshold proxy signature is a branch of proxy signature. It puts threshold signature and proxy signature together, and distributes the right of the proxy signature to avoid the abuse of privilege. Threshold proxy signature has attracted the attention of researches by the domestic and foreign scholars with its distinctive advantages and practical value.Most of the threshold proxy signature schemes are based on the decomposition of large numbers and the discrete logarithm problem. Elliptic curve cryptosystem has became a hot research in recent years because of its "short key, fast processing speed" characteristics. With the introducing of elliptic curve cryptosystem in threshold proxy signature, it has played an important role in specific applications (such as electronic voting, electronic payment, etc.). There are some problems in threshold proxy signature schemes:can't resist the conspiracy attack and the forgery attack, the traceability of the participation members in agency, the abuse of agency privilege. Therefore, the author improves and designs three threshold proxy signature schemes to make them become the secure signatures. The main studying results of this thesis are as follows:(1) This thesis studies the threshold proxy signature schemes based on discrete logarithm problem. Specifically, there are some security flaws in an existing threshold proxy signature scheme. Other scholars have analyzed the scheme, and found that the scheme can not resist the conspiracy attack and the forgery attack. They have also designed an improved scheme. But after proving, the improved scheme still can't effectively resist the conspiracy and forgery attack. This thesis proposes a new improved scheme. The new scheme can solve the conspiracy attack and the forgery attack problem, and it has strong unforgeability and strong undeniability. The new scheme solves the security problem in original scheme.(2) This thesis studies the traceability of the participation members in agency. According to the thought of an existing traceability threshold proxy signature scheme, the author designs a new threshold proxy signature scheme, and changes the discrete logarithm cryptosystem of the original scheme into elliptic curve cryptosystem. The new scheme has realized the anonymous traceability of the participation members in agency under the condition of the security of the threshold proxy signature.(3) This thesis studies the designated-verifier threshold proxy signature scheme. The designated-verifier threshold proxy signature has very big effect to protecting the signers and limitting the right of signers as a special part of the threshold proxy signature. One of the existing designated-verifier threshold proxy signature scheme based on elliptic curve is analyzed its security and complexity, and this proves that the scheme is secure and efficient. The author constructs a new designated- verifier threshold proxy signature scheme by the idea of the proxy signature scheme. The new scheme has the characteristics of the designated-verifier, and it can against the conspiracy and forgery attack. The efficiency of the new scheme is higher than the same condition of the schemes.
Keywords/Search Tags:proxy signature, threshold proxy signature, elliptic curve, conspiracy attack, traceability, designated-verifier
PDF Full Text Request
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