An untraceable forward-secure blind signature scheme

Due to the unlinkability (blindness) property, blind signature techniques have been widely used in the anonymous electronic cash and anonymous voting systems. We now consider the key problem of exposure in the use of blind signatures which is a very serious problem, such as for the application of the electronic cash system. Based on Hwang et al.'s blind signature, we propose a new forward-secure blind signature scheme which preserves the validity of past signatures, and prevents a forger from forging past signatures even if the current secret key has been compromised.