Cryptanalysis of two proxy blind signatures based on DLP

Proxy blind signature technology integrates the properties of both the blind signature and proxy signature; it can be adopted in applications such as e-cash or e-commerce, etc. In this paper, cryptanalysis of two blind proxy blind signature schemes is made, which show the first scheme doesn´t satisfy the property of unlinkability and the second suffers from a kind of forgery attack. And to overcome the weakness of the previous schemes, a new proxy blind signature scheme based Discrete Logarithm Problem (DLP) is presented. It is proved that this scheme is more secure than the previous schemes.