Research On ID-based Proxy Blind Signature Scheme

Information security is one of the most important problems in modern information society and becomes a new important subject in the information science. Digital signature, which can prove authentication, integrity and non-repudiation, is one of the key techniques of information security. As the deepening of digital signature research and the rapid development of E-commerce and E-governance, the standard signature, which is a simple simulacrum of handwritten signature, can not still meet the need in practice, thus making research on the digital signatures with additional properties becomes a main research direction in digital signature.The main content of this paper is the research of proxy blind signature scheme. As a kind of new digital signature schemes, proxy blind signature is first proposed by Lin et al. in 2000. Proxy blind signature scheme has the characteristic of the proxy signature scheme and the blind signature scheme. So it can be applied in the field of electronic commerce and electronic cash etc.In traditional public key infrastructure ( PKI ) system, managing public key certification causes problems of complexity and high cost. Fortunately, identity-based cryptography has solved these kinds of problems, and it is also a good replenisher to PKI system. In the last couple of years, the bilinear pairings has been applied to various applications in cryptography. They are basic tools for construction of identity-based cryptographic schemes. Although identity-based signature scheme has the advantage of short signature size, the time-consuming computation of the pairing lowers the efficiency of the scheme, thus restrict the application of identity-based signature.The main work in this paper is to research on some problems about current identity-based proxy blind signature schemes. The main results are as follows: 1). Several existing identity -based proxy blind signature schemes are analyzed. This paper shows that the Li et al. 's scheme does not posses the unforgeability property. The original signer can forge a valid proxy blind signature for any message, and the proxy signer can misuse the signing capabilities. At the same time, the proxy signer can make a linkage between a signature and the corresponding message of signing protocol after signing.2). An improved new identity-based proxy blind signature scheme is proposed based on the existing proxy blind signature schemes. The security of the new scheme is also discussed and shown that it can resolve the security problems existing in the original scheme.3). To avoid the key escrow problem in identity-based signature scheme, a new identity-based proxy blind signature scheme without trusted private key generator (PKG) is proposed. Analysis shows that the proposed scheme can satisfy all the required properties of a proxy blind signature. Furthermore, its efficiency is also better than that of the existing ones.