Design And Security Analysis Of Proxy Signature Schemes

The digital signature is a very important part of the public-key cryptology, proposed at the last of 1970s. The digital signature is a very important implement to achieve authentication, which is designed to provide the digital counterpart to a handwritten signature. The proxy signature is proposed by Mambo et al in 1996 and has received a great deal of interest. It is a very important part of the digital signature and can be regarded as an electronic seal. In a proxy signature scheme, a signer does not sign a message himself but delegates his signing capability to his proxy signer to sign. In 2001, Boneh et al proposed the short signature from bilinear pairing based on discrete logarithm problem. The short signature has many important advantages. For examples, keys and signatures are short, and high security.In this dissertation, two new proxy signature schemes from bilinear pairing are proposed, which are all based on discrete logarithm problem on GDH group. In the first scheme, the proxy signing ability can be revoked during the period of validity. Then, the malicious signer can not sign messages any more. Moreover, in this scheme secure channels are not needed. In the second scheme, the proxy signer's ID can be hidden during proxy signing. This scheme is also from bilinear pairing based on discrete logarithm problem. Moreover, the trusted authority is not needed in this scheme.