摘要
Combining the concept of partially blind signature with the concept of directed signature, we introduce a new concept of convertible directed partially blind signature (CDPBS), in which only the signer and the user can verify, confirm and disavow the validity of given signatures and convert given signatures into universally verifiable ones, to meet the need of signing personally or commercially sensitive messages. We give a formal definition of CDPBS and propose a concrete provably secure CDPBS scheme. The proposed scheme is efficient and secure, in which its unforgeability is the same as that of the Schnorr's signature scheme and its untransferability relies on the hardness of the decisional Diffie-Hellman problem. Furthermore, by letting the user's private key be a common constant, the proposed scheme can be used as a normal partially blind signature scheme.
Combining the concept of partially blind signature with the concept of directed signature, we introduce a new concept of convertible directed partially blind signature (CDPBS), in which only the signer and the user can verify, confirm and disavow the validity of given signatures and convert given signatures into universally verifiable ones, to meet the need of signing personally or commercially sensitive messages. We give a formal definition of CDPBS and propose a concrete provably secure CDPBS scheme. The proposed scheme is efficient and secure, in which its unforgeability is the same as that of the Schnorr's signature scheme and its untransferability relies on the hardness of the decisional Diffie-Hellman problem. Furthermore, by letting the user's private key be a common constant, the proposed scheme can be used as a normal partially blind signature scheme.
基金
Supported by the Innovation Foundation for Young Tech-nological Talents of Fujian Province (2005J055), the Science and Technology Program of Department of Educatuon of Fujian Province (JA04250) and the Natural Science Foundation of Fujian Province