A Study And Design Of Threshold Proxy Signature

The concept of proxy signature, introduced by Mambo, Usuda, and Okamoto in 1996, allows a designated person, called a proxy signer, to sign on behalf of an original signer. Since then many variant schemes have been proposed to achieve the varied specific requirement in a proxy signature situation. A (t,n) threshold proxy signature scheme is a variant of proxy signature scheme in which the proxy signature key is shared by a group of n proxy signers in such a way that any t or more proxy signers can cooperatively sign messages on behalf of an original signer. It is widely studied for its good performance, such as high security, decentralization of management and so on.Verifiable secret sharing (VSS) is an important tool in the design' of cryptography protocols and threshold signature schemes, and it is widely used in many proxy threshold signature schemes. Lagrange interpolating polynomial is a basic mathematics tool in a verifiable secret skaring scheme. In the thesis, we will introduce it first and propose a few traditional VSS schemes, which are widely used in most of threshold proxy signature schemes.Discrete logarithm problem and RSA constitute the base of the most of threshold proxy signature. In the thesis, we will propose a new scheme which based on elliptic curve discrete logarithm problem (ECDLP). Compared with the traditional cryptography system, a system based on ECDLP has stronger security, shorter key length, quicker speed, lower requirement for system parameters and bandwidth. At first, we will introduce SLH scheme, a traditional threshold proxy signature scheme. Then we will propose our new scheme which shows higher performance compare with the former. Because our scheme bases on ECDLP, it has shorter key length and signature length than the former.In addition, on the base of the new scheme, we develop a program with VC, which simulates the process of generation of a signature and can be provided for reference to software development.At last we will introduce a new electronic commerce transaction projectbased on idea of threshold proxy signature.